The $85,000.00 GM 4.2L Engine Repair

MRRSM

Lifetime VIP Supporter
Hello To All Who Dwell at GMT Nation!

This first post of mine is going to be a DOOZY... It all stated back in December of 2014 and the concern was my son complaining of a serious misfire in the 2002 Chevrolet Trailblazer LS. I ran some OBD II fairly sophisticated checks with a good tool... but ultimately I made a more conclusive diagnosis (Bad/Leaking Valves) by holding a strip of writing paper over the exhaust tail pipe and when the strip of paper fluttered violently and was suddenly sucked back up inside the pipe, it was pretty clear to me that after 240,000 miles, this white SUV was badly in need of a valve job.

What follows covers more than just replacing the engine head on this unusual motor and while I am not trying to discourage anyone from doing this repair... unless you are possessed of much patience, much money and have at least a seasoned amount of mechanical skill... it might be worth paying to have a qualified mechanic do the job. Just by virtue of the technical difficulties from the outset... this repair will become a long road...with no turns in it.

These are the requirements in my opinion for doing the best possible repair in this situation... but I realize these might have to be paired down for obvious reasons:

Manuals and Other References:

GM OEM Factory Carline Series Service Manuals (Full Set) Pale Blue Covers
2004 Timing Chains and Gears (1992-03) (Timing Chains & Gears: Domestic & Imports) Alldata
Haynes Service Manual 2002 Chevrolet Trailblazer, Etc...
YouTube Videos where available

Lubricants and Sealants:

Mobil 1 Oil with K&N Oil Filter
Permatex 81950 Ultra Slick Engine Assembly Lube, 4 oz.
Genuine GM Fluid 12378521 RTV Engine Sealant – 3 - 5.3 oz. Cartridges Case Sealer


General Maintenance: (Work Done By Me So Far with Parts I Purchased NEW))

K&N Air Filter E-1009
New GM Throttle Body 2002 only TrailBlazer Envoy Bravada 4.2L 25312095 TPS
Fel-Pro Fuel Injection Throttle Body Mounting Gasket 61337
Right+Left Side New Headlight Lamp Set of 2 Chevy Clear lens Halogen 2002 Pair
A3C10 02 2002 03 2003 04 2004 05 2005 06 TRAILBLAZER AIR INT RESONATOR OEM
AC-Delco OEM PCV Hose - Trailblazer Envoy Rainier Bravada w/4.2 (24577310)
AC-Delco OEM GM - ISUZU - OEM IGNITION COILS (6) -Premium Quality
General Motors 2.8L / 3.5L / 4.2L Coil on Plug Boot / New Ignition Coil Boots (6)
Stabilus Trunk lid Lift Support New Chevy Chevrolet Trailblazer SG230044 (2)
Envoy Trailblazer Rainier Ascender Left Driver Rear Door Window Motor Regulator (TBD)
AC-Delco 12578069 GM Original Equipment Crankshaft Balancer Kit with Washer (TBD)

Transmission Replacement: Completed by me...
2002 Chevrolet Trailblazer 4L60E Transmission, 4.2L, 2WD, w/ Converter, Re-man 3yrwty
USA Heavy Duty Bushing 15785087 Shifter Shift Cable Trailblazer Chevrolet
Dorman 917-615 Speed Sensor
02-09 Trailblazer Envoy 04-07 Buick Rainer 4.2L Motor & Trans Mount Set 3-PCS
AC-Delco 4L80E 4L85E Cooler Line Fitting Center of Case Rear 1997-up New OEM
AC-Delco / GM 15817233 Transmission Cooler Line OEM
LUBEGARD Lube Gard Automatic Transmission Flush ATF (6) Pack 95001
GM NEW OEM ALUMINUM REAR DRIVESHAFT 15152336 15833881 with Yoke and U-Joint
GM 4L60E Removable Bell Housing Style Transmission Case
10 Gallons of HQ Transmission Fluid (Repeat Flushing of Coolant Lines & Cond and Refill)

Fuel System Refresh: ( I bought the AC-Delco Fuel Pump already... work is pending)


Engine Head Replacement: (I Have Already Purchased All of These Components ad work is pending)

RockAuto LLC Re-Manufactured Aluminum Engine Head for 2002-2004 GM Atlas 4.2L Motor
New Genuine GM 24100263 Engine Camshaft Bolt
New Genuine GM 12565425 Bolt
Fel-Pro ES 72195 Cylinder Head Bolt Set
Fel-Pro Hs26214Pt Head Gasket Set
GM OEM 4.2L TRAILBLAZER OIL PAN
AC-Delco 15-11073 GM Original Equipment Engine Coolant Thermostat Housing
GMC O2 Oxygen Sensor SG1823 15894 234-4344 ES20113 21044 4 wire w/ OEM Plug
Dorman 674-777 Exhaust Manifold
Dorman 917-010 Variable Valve Timing Solenoid
Dorman Kit Exhaust Stud Front Full Size Truck Chevy GMC Sierra 03133
Dorman 03413B Exhaust Manifold Hardware Kit
Dorman 674-777 Exhaust Manifold Kit
Cloyes 9-0195S Timing Chain Set
Sealed Power 224-53582 Oil Pump Repair Kit
Fel-Pro Tcs 45051 Timing Cover Gasket Set
AC-Delco 15-40133 GM Original Equipment Engine Cooling Fan Clutch
Stant 14659 Thermostat And Housing - 190 Degrees Fahrenheit
AC-Delco D1843A GM Original Equipment Engine Oil Pressure Switch
AC-Delco 251-731 GM Original Equipment Water Pump
AC-Delco 251-2029 GM Original Equipment Water Pump Gasket
Cloyes S908 Timing Driven Gear
AC-Delco Re-Manufactured VVT Gear

Tools: (I Have Purchased These Over Time)

INGERSOLL-RAND 1210 1/2" PNEUMATIC RIGHT ANGLE RATCHET WRENCH 1210
CROSS BEAM FLOOR JACK LIFT ATTACHMENT
BRASS QUICK RELEASE AIR LINE COUPLER CONNECTOR SET FOR COMPRESSOR TOOLS 5PC SET Air Blow Gun w/ Rubber Tip, 3 Needle Tips & Medal Tip Heavy Duty
Mity-Vac 7300 Air Operated Pneumatic Oil Vacuum 2.3 Gal Capacity
COOLER LINE FITTING 4L60E SNAP IN TYPE 4L65E 4L70E TRANS OEM M30 M32 M70
Vacuum Transmission & Differential Suction Gun auto tool
AC-Delco Air Conditioner System Flush Canister Gun Kit R134 R12 R22 R410 R404
4 piece 1/4" to 3/8" 1/2 inch Drive Socket Adapter Reducer Air Impact Set NEW
Sunex Tools 3/8" Drive 12 Point 13 Piece Metric Deep Impact Socket Set – 3682
Sunex 3504 3/8" Dr. 4 Piece. Wobble Drive Extension Set
Transmission Tail Shaft End Cap Plug TH350 C4 200-4R 700R4 4L60E Power-glide
Miller SPX Tools 9318 Fuel Pump Lock Ring Wrench
KENT MOORE TOOLS J-21366 TORQUE CONVERTER HOLDING STRAP (56)
Kent-Moore Crankshaft Button Plug J-38416-2
Kent Moore J-38188 Cylinder Head Broken Bolt Extractor Set Kit Tools 2.5L Engine
KENT MOORE TOOL GE-48326 SEALANT TUBE DISPENSER TOOL
Kent Moore Camshaft Sprocket Holding Tool #J-44222 In-Line 6 Cylinder 4.2L GMT360
Kent Moore GMT360 Rear Main Seal Installer #J-44227 In-line 6 Cyl. Envoy Etc.
KENT MOORE TOOL J-41478 & J-41665 FRONT OIL SEAL INSTALLER / CRANKSHAFT
KENT MOORE TOOL GE-48326 SEALANT TUBE DISPENSER TOOL
Kent Moore GMT360 Rear Main Seal Installer #J-44227 In-line 6 Cyl. Envoy Etc.
Kent Moore EN-46124 High Feature Engine Kit Extra Tools
KENT MOORE TOOL J-44219 COVER ALIGNMENT PINS
Kent Moore Crankshaft Balancer & Hub Remover Puller #J-44226 In-Line V6 GMT360
Kent Moore SPX GM - EN-48034 - Harmonic Balance Installer 4.2L Engine
KENT MOORE TOOL J-44222 IN-LINE ENGINE CS SPROCKET HOLDING TOOL GMT360
KENT MOORE TOOL J-44217 TIMING CHAIN RETENSION TOOL
Kent Moore J-44221 Camshaft Holding Tool
KENT MOORE EN-48464 LOWER TIMING GEAR RETAINER Aluminum Wedge
KENT MOORE TOOL J-41478 & J-41665 FRONT OIL SEAL INSTALL / CRANK BALANCER
450 Lb. Capacity Low Lift Transmission Jack. Remove & Replace Transmissions
GM 4.2L Camshaft Holding Tool
OTC 4554 1/2" Drive Torque Angle Gauge
AC-Delco ARM602-4 1/2-Inch Torque Measurement Adapter 4-147.6 ft-lbs
TEKTON 24335 1/2-Inch Drive Click Torque Wrench, 10-150-Foot/Pound
11 mm x 1.5 High Speed Steel Bottoming Tap
Kent Moore Differential Locknut Bolt Extraction Kit ST-1440
Wilmar W80498 Gm Fan Clutch Wrench
Assenmacher Specialty Tools 8032 32mm Fan Clutch Wrench
OTC 6667 Harmonic Damper Puller
Innovative Products of America 7886 14" Long 14mm Thread Top Dead Center Indicator


Here are three links specific to this Trailblazer set of repairs located on my Photobucket site presence. These are indexed on a long library list of other repairs and mechanical inventions that may be of interest to the members.

Fan Clutch Repair Tool (I have solved many mechanical problems with invention)
http://s557.photobucket.com/user/60dgrzbelow0/library/TRAILBLAZER_2002?sort=6&page=1

Chevrolet Trailblazer LS New OEM Engine Parts
http://s557.photobucket.com/user/60dgrzbelow0/library/0000TRAILBLAZERENGINEREPAIR/TRAILBLAZERENGINEPARTS?sort=3&page=1

Chevrolet Trailblazer LS Specialty Engine Repair Tools
http://s557.photobucket.com/user/60dgrzbelow0/library/0000TRAILBLAZERENGINEREPAIR/TRAILBLAZEREPAIRTOOLS?sort=3&page=1

The reason this job rounds off mathematically to the enormous expense of $85,000.00 is because I ruptured two discs at L-4-L-5 while doing this repair and lost the ability to walk from February of 2015 until my back operation ($50,000.00) in April of 2015. In between, my wife had to buy a new vehicle since I could no longer drive her to and from work (She bought 2013 Nissan Altima for $20,000.00 +)...and of course, I had to get transportation for my son so he would not lose his job and give him the freedom to drive to and from work, etc. because I could not get out of bed to finish the Trailblazer repair. So I was willing to spring for a a 2003 Chevrolet Silverado 1500 pickup truck (Well worth just $10,000.00), since I was certain I would need his help using that truck to work on the Trailblazer as soon I could ambulate. Whatever she spent besides, plus parts and tools for this epic repair rounds off to around $5,000.00.

So now that I have figured out how to navigate with cane, albeit a bit on the clumsy side and with a "cuirass" or armor-like back brace... I will soon be solving the problem of the need to pick up heavy metal parts, engine heads/headers, exhaust manifolds, etc. by modifying my two ton hydraulic engine lift with the addition of three bolt/chain on pulleys and a 1350 LB Electric Hoist with fine motor control to pre-position the long hydraulic arm and then use the electric hoist action to maneuver or wield weighty objects including the motor and transmission around inside the engine compartment and not risk further injuries. (See my Trailblazer Repair Tool for a look at the hoist and pulleys to be added)

This is very important to mention here... In his play "Hamlet" Shakespeare coins a perfect observation of what happens when we are faced with mounting problems:

"Troubles come... Not as Single Spies... But in Battalions!"

If you stroll around your neighborhood and knock on any body's door, invariably you will find some poor soul who has more troubles than you have. I've always been an optimistic person... so... unless something happens to me that makes me have to take a "Long Dirt Nap"... I will overcome my present difficulties and pound this Trailblazer back into shape... and speaking of pounding... I had the engine partially taken apart before I got hurt reaching through the driver's side wheel well to un-install the starter motor and my world went to sh*t. The next "pounding" will be the necessary duty of trying to loosen the 15 main engine head bolts by lightly hammering on each bolt IN THE ORIGINAL REVERSE TORQUE PATTERN! with a flat faced steel punch. I intend to be the first person in the western hemisphere to have successfully removed the Atlas 4.2L Engine Head ...without snapping of ANY of these @%!&*!!! Stretch-to-Yield Bolts. Of course from now on... I will be adding photos of every work segment if this is helpful to us all. If you see me getting into trouble with any bad approaches to the work... don't be shy... you can take a swing at my chin if you need to get my attention... and I am ever a good student and learner. :>)
 

Denali n DOO

Silver Supporter
Welcome to GMTNation! Nice first post(s)! Glad to have you aboard.:thumbsup:
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Thanks to you all, Gentlemen... I may not live long enough to wear the "Gold and Silver 'Mithril' Chain-mail" ...but while I am visiting here...I'll do my very best to bring interesting and productive information to the site...oh...and I promise to steal my share of ideas, too...! :>)
 

Mounce

Well-Known Member
Interesting, Welcome aboard. Take it easy. :tiphat:
 

Sir ffeJ

Well-Known Member
I can relate to the back crap. Welcome aboard sir.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Thank You... Sir Golitech... err ... I mean... Sir Jeff... its nice to be here... you folks have already given me more reasons to move around now and be all I can be once again as a mechanic and just get on with it.

I mentioned earlier that I will need to begin working on the engine by breaking the TTY Head Bolts loose with some "controlled violence" and although I have never heard of anybody using what I intend doing by following a reverse of the Install Torque Pattern... this link seems very encouraging:

http://www.aa1car.com/library/torque_to_yield_tty_head_bolt_tips.htm

Also..I very much would appreciate some keen guidance here...

I have been puzzling over a possible problem in the fact that since I just did the "Unboxing" of the re-manned completely assembled cylinder head today... this is the first time I have actually looked at it since it arrived many months ago! It has been resting, sealed up inside a giant plastic transfer case (see aforesaid link to my photobucket on Trailblazer Engine Parts).. undisturbed until today.

Anyway... it just dawned on me that as long as I use the Special K&M Dual Camshaft Holding Tool necessary for alignment and removal of the VVT/Intake Gear and Timing Chain during the head removal... then it strikes me that as long as I align both the camshafts on the new head using same tool in the identical fashion... then I should be able to just carefully lower the new head in place atop the new head gasket and NOT have to remove or disturb the dual camshafts/lifters/rockers, etc. in order to get everything to match up exactly in the original position and NOT contact the pistons...Yes?... Isn't that right?. I confess that I did not realize the engine head they would send to me would come with the entire Camshaftst/Pushrods/Roller Rockers all set in place and "Good to Go..." I know that common sense tells me that my theory of installation should be right... but you know what they say about working on "Interference Engines":

"If you are NEARLY CORRECT... Then you are PRECISELY WRONG..."

So if everyone confirms that this will be okay... It will ease my mind and happily eliminate having the need to assemble 24 sets of components while bending over the hood with my "Aching Back". Thanks in advance for looking into this issue for me.
 

Darkrider_LS

Moderator
Well...that is def quite the introduction...With that said...Welcome to the Nation!
 

Mooseman

Moderator
Welcome to the Nation! Quite the story and I think an inspiration to those of us who think they "have it bad".

Having seen the inside of this engine more often than I should have, I can tell you that it is a bitch to work on. Are you doing the work with the engine in or out of the truck? Reason I ask is because you need to remove the oil pan to remove the timing chain because there is no way to remove the head and hold the chain in place at the same time. Have a look at my threads on
How to replace I6 timing chain and tensioner in the truck. Yours being a 2wd makes it a bit easier but not by much. Since you're already in there, you should replace the chain tensioner too (didn't see it in your long list of parts).

If you bring the engine to TDC and have the timing marks aligned with the dark chain links and the holding tool before taking it apart, you should be good with the new head aligned the same way.

Good luck and if you need any info, lots of good people here will be glad to help.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Thanks for looking in on me with this @Mooseman ... The links to my photobucket have all the parts and tools for this project in separate albums. What is missing there are the images of a special aluminum wedge like tool that slips down that narrow channel and gets wedged in between the chain tensioner and the chain to lower crankshaft sprocket so the head can be removed and not have the timing chain drop off and get wonky. Once delivered, the handle of the tool unscrews and then the chain holders can be relaxed. It's too bad some brilliant TIG welder has not created an alternative front cover that would give access without having to remove the oil pan and oil pump situation. I have a new VVT Actuator gear and new Cloyes Intake Gear to install with the GM tool so I am hoping the chain is not too stretched after a quarter of a million miles lubed with Mobil 1 exclusively. We will see.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Thanks for the "Hello!"

And for The MooseMan...

I am not certain if this tool was around when MM did his FTW repair... But this is where I purchased this unique tool that gives another alternative to how it can be done (and Thanks to Freedom Racing for NOT selling it at the higher K&M price). This was probably designed by someone at a "Stealership" after they received way too many complaints about the labor costs involved in having to yank the oil pan on what otherwise would be a repair manageable by most thoughtful and cautious mechanics. IIRC... There is a GM Service Bulletin connected with how to use this damned thing somewhere out on "The Internets" involving where to apply it exactly and how to hammer it in place and then carefully unscrew the handle to facilitate the engine head removal and installation.... and of course....the need to "Remember the Wedgy" and screw the handle back into it and get it the hell out of there after the V-V-T Actuator and Intake gear sets are aligned to the black links and fitted back under the Timing Chain:

http://www.freedomracing.com/lower-timing-gear-retainer-en-48464-alt.html

I took some more detailed images just now that better display the geometry of this weird but seriously Cool Rescue Tool:

Chevrolet Trailblazer LS 4.2L Atlas Engine Specialty Engine Repair Tools
http://s557.photobucket.com/user/60...INEREPAIR/TRAILBLAZEREPAIRTOOLS?sort=3&page=1

"Whoever has the MOST TOOLS before he Dies... WINS..."
 

Mooseman

Moderator
That's right. I totally forgot about that wedge tool. I wonder if it prevents the chain from skipping the lower timing gear. Anyway, it looks like you've done a lot of research already and know where you're going.

Arm yourself with lots of patience, you'll need it!
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Moose...
Yes. This Wedgy Gizmo will prevent the Timing Chain to Lower Crankshaft Timing Sprocket to lock into place and not lose its position as the chain is allowed to relax. As I noodle down through the Timing Set removal... I'll take some "One-Over-The-World" Top Down views as close as I can get down inside the front of the engine.

"Una Pregunta Mas..." (One More Question...)

Once the engine head is off...can the Chain Guides be accessed through the two circular plugs on the front upper engine cover? I ask because even if I cannot remove and replace the old Chain Tensioner... I would still like to install as many new components as possible before I button up the motor.

Moose... With your permission... I have a spanking clean extra Aluminum Oil Pan for this 4.2L Engine that I can take close up images of to add to your original "How to Remove the Engine Oil Pan on th I6 Engine"... mostly focusing on the areas where you instructed us in breaking the tight seal to the base of the engine with your brilliant "Two Bolt Pry Bar" solution.
 

Mooseman

Moderator
Sure. Just send me the pics and I'll add them. Thanks!

I don't think you can remove the guides from the top. Plus the wedge pushes on the chain which pushes the guide which pushes the tensioner.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Afternoon, Moose...

I ran into a bit of difficulty with my imagery because of the "Byte-Size" limiter for direct loading images greater than one megabyte in size, so instead, I just uploaded to the link to my photobucket with the rest of the engine parts and they are free to download if you see any or all of them listed on the full Page 1 showing and some more on the top of Page 2 that might help to illustrate or amplify your original post on this matter... you are welcome to everything I have in every library album I have shown there as well. To save you the time of having to doctor the specific threaded hole points of concern to your instructional post via Photo-Shop, I painted around them, both on the top and on the bottom of the oil pan with a Red Sharpie Enamel Oil Paint marker for ease of recognition. Without doing that, all those holes look alike down there. [I know ... There's Bad Joke in there somewhere :>)]

http://s557.photobucket.com/user/60dgrzbelow0/library/0000TRAILBLAZERENGINEREPAIR/TRAILBLAZERENGINEPARTS?sort=3&page=1

Some additional thoughts about the Oil Pan that concern my own fix in progress:

When I found this illustrated pan on eBay, I was able to snag it for $35.00 and Free S&H, so I was not too upset when it arrived in less than the promised "Pristine and Clean" condition the Original Owner/Seller had suggested... but it well and truly serves me here to help describe my responsibility to never take any body's word when it comes to how clean an engine part needs to be and remain safe and satisfactory. As you can see from the strange and squiggly objects adorning the paper plate photos... those are only a fraction of the residual GM Split Case Adhesive that was applied as a single bead at the GM Factory Assembly Point and remained intact until the Original Owner pulled the motor and followed Mooseman's advice on how to get the oil pan and engine base separated.

I employed some of the nifty sub-tools hidden inside my "Leatherman Wingman" fancy Duzitall pocket knife and managed to coax all that crap out of the "Mortise and Tenon" slots along the centerline and between the bolt holes of this sturdy aluminum crankcase slash oil pan in around 30 minutes with a flashlight and a flat long razor blade from a carpet knife to clean the same goop off of all the flange surfaces. This engine uses every aluminum bolt-on component like load bearing members in a building... so whatever can be done to ensure that integrity can only be enhanced by thoroughly cleaning all their mating surfaces.
 

Mooseman

Moderator
I added the pic. Thanks!

For uploading pics here, if you have a Windows computer, get Image Resizer. It's an old Windows XP PowerToy that has been adapted to work with newer versions of Windows. Right Click>resize>done.

Yes, almost everything is used as a structural member on this engine. And that the differential is also bolted to it makes it that much more important. It's an engineering feat but a maintenance/repair nightmare.

Speaking of which, looking at your pics of the parts... Damn! You replacing everything but the short block? Saw you have a full timing chain set so you will be removing the front cover. I even saw the new oil pump there.
 
Last edited:
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Moose...

Glad to make a modest contribution to your work. As for the procedures I follow when doing any major repairs... I decided 50 years ago when I started turning wrenches as teenager to repair or replace with new... every single component that of necessity must be either disassembled or completely removed in pursuit of the major repairs at hand. The reason is because... Like General George S. Patton once said, "I never like having to fight for the same ground in battle..twice." And as sure as there are carts to horses... If I were to put back into the motor the old components that have endured the wear and tear of over 240,000 miles... either one or all would fail as soon as everything was put back together. I know this can be expensive... but not if a good overall purchase and acquisition plan and work time line is followed. When the work is done... then you can sleep like a baby knowing everything inside and bolted to that engine is OEM AC-Delco quality and brand spanking new!

If you examine all of my photobucket libraries... You will note that I tend to document not only the before and after work in imagery... but also include as many factory part numbers and box ends of these components as possible in order to help the next person concerned with these repairs not chase their tails in pursuit of getting the right replacement parts. What remains to be seen is whether I will be compelled to remove the oil pan to put all of these front engine components in the engine. My present and on-going physical rehabilitation may prevent me from diving under the SUV to remove that crank case. Your original work is my present encouragement and I intend to supplement your fine explanations of how to do all of this ...by memorializing each and every step I take from here on. More of us will attempt this difficult task because you have prepared the battleground in advance for us all!
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Many years ago... I got so frustrated with the constant need to either build anew desktop and laptop computers for each member of the household that I had to make a sea change in my approach to the problem. No thanks to "Moore's Law" and the growth of home computing on a staggering scale and married to that hardware repair/upgrade roller coaster ride... And so this was a repair loop that I very much wanted to escape. Powering it all was the Microsoft Windows and its perpetual bottomless pit of need for money and constant need for overcoming the Blue Screen of Death. So I decided to take Linux under my wing and learn how it worked as a completely free and open source operating system. It follows on that I will either have to find a Fedora or Debian Linux counterpart to your suggested Windows application... or download that very Image Resizer and try running it using Linux Wine.
 

Nexus1155

Well-Known Member
Props to you man! I went through close to the same situation with mine. Stumbling that after a set of coils and plugs did not budge, seafoamed, mystery oil. compression tested. then leak downed. Leak down said good bye intake valve in cyl 1. toasted. had a small piece missing. Dad ended up sending it to a shop when I was on vacation and had the head replaced to the tune of $6-8k. I wanted to do it myself, but after reading your noble attempt I am sure glad I didn't. Even though I had some other plans in the works including head port and cams while I had the head off! (efi-diy did a lot of work on this if you want to look into it 100hp gains) Glad to hear you are doing better my friend. Welcome aboard. Don't listen to the doctors and drink the koolaid. Been there too with back issues from a snowboarding accident. Also, imgur works great for pictures too...
 
Last edited:
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
Last edited:

Mooseman

Moderator
At $8k, you could probably get a completely rebuilt engine installed. Labour wise, it's probably cheaper to replace the engine than the head.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Note to Admin Personnel:
Somehow, I managed to make quite a few duplicate image uploads to this post and I would be grateful if you could edit/delete any duplicates. Thanks in Advance -=Bob=-

Okay... I know its around 5:00 AM and I should be asleep like most normal people...but my mind has been dormant too long in moving this project ahead and now that I can actually move around again myself, I will not rest very well until the job is done as good as it can be. Earlier this afternoon, I opened the hood on my son's 2002 Trailblazer to look over the engine compartment and document the use and position of two unusual but necessary Special Tools to facilitate and prepare this engine for the organized removal of the engine head.

As you can see/read in the attached printed service Bulletin addition to this text, there are quite a few DTC Codes that can be thrown and cause the service technician to have to dive in and delve deeply into the mechanical workings of this bizarre but powerful motor. I am recommending a very careful read of this information as it gives up all of the necessary earmarks of possible problems involving not getting the engine timed right the first time upon re-assembly.

Examine this document very carefully and you can read between the lines that their own GM Service Staff must have FUBARed this very repair enough times to warrant somebody in the GM Engine Planning and Building areas to put out this dialogue in detail to warn them to pay very close attention when doing this work. This document describes the various positions the engine components must be in perfectly, such as having the Number One Cylinder perfectly positioned at Top Dead Center and having both the Intake ad Exhaust Camshafts positioned with their flats facing upward and level, one with the other...and lastly ... the visual appearance of the word DELPHI evident on the lower section of the Variable Valve Timing Actuator showing as level and even with the upper front portion of the Engine Cylinder Head. The attached images show where and how these tools are placed to do both jobs to first acquire TDC and then apply the Camshaft Holding Tool correctly.



#PI00156C: SES Light with a P1345 or P0016 and a Possible Rough Idle - kw 4.2 camshaft condition control DTC idle intermittent light LL* MIL performance poor repair rough solenoid - (Jan 26, 2005)
Subject: SES Light with a P1345 or P0016 and a Possible Rough Idle

Models: .

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.
Condition/Concern:

Some 2002 - 2004 models that are equipped with the 4.2L (VIN S - RPO LL8) engine may experience a SES Light due to a P0016 or P1345 DTC and a possible rough idle.
Recommendation/Instructions:

If the SI diagnostics do not isolate a cause, the following information may help:
- Control of the Cam Phaser Actuator solenoid is inhibited when a P0016 (04 Model Year) or P1345 (02 - 03 Model Year) DTC is stored.
- If this DTC started after recent internal engine repairs, inspect for proper engine mechanical timing. With the camshaft cover removed and the #1 cylinder at top dead center, make sure that the darkened chain links are lined up with the alignment marks on the exhaust and intake cam sprockets. At this point, J44221 should fit over the rear cam flats and the word Delphi (on the front of the Cam Phaser Actuator sprocket) should be parallel with the front edge of the cylinder head. Note: It may take up to 14 crankshaft revolutions before all timing alignment marks line up with each other.
- Engines built after 2/5/01 include a thin friction washer (P/N 12573950) between the dampener and the crank gear and the torque specification was increased to 110 ft-lbs plus 180 degrees to prevent crankshaft gear and alignment pin damage. If there is any history of the crank dampener bolt ever being loose, the crankshaft gear and alignment pin may be damaged, which can cause these DTCs.
- If a P0016 or P1345 is resetting without any engine performance concerns but the SI diagnostics and the above information did not isolate a cause for the DTC, replace the Cam Phaser Actuator sprocket.

#PIP3659A: SES Light After Internal Engine Repairs Due to DTC P0016 or P1345 - keywords after cam correlation crank DTC induced previous replacement seal since spring timing valve - (Jan 4, 2006)
Subject: SES Light After Internal Engine Repairs Due DTC P0016 or P1345

Models: 2004 Buick Rainier
2002-2004 Chevrolet TrailBlazer
2002-2004 GMC Envoy
2002-2004 Oldsmobile Bravada
with 4.2L Engine (VIN S - RPO LL8)

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:

Depending on the model year, a P0016 or P1345 may be encountered after internal engine repairs that required resetting of the timing chain tensioner or removal and installation of the exhaust camshaft actuator sprocket. This may be the result of a mistimed engine or damaged exhaust camshaft actuator.
Recommendation/Instructions:

If this concern is encountered and the SI diagnostics do not isolate the cause, review the following information and inspect for a damaged exhaust camshaft actuator or mistimed engine as necessary:

- The spline style exhaust camshaft actuator used on 2004 model year and earlier 4.2L engines is designed to operate between 25 degrees of retard and 0 degrees (full advance/rest/clockwise position). There is a stop tab inside of the camshaft actuator that prevents the exhaust cam from advancing beyond the rest position under normal operating conditions. This tab can bend if the exhaust cam/actuator is forced to rotate beyond the rest position (full advance/full clockwise) during internal engine repairs. If this occurs, it may be noted that the reluctor portion of the actuator is a few degrees more advanced (clockwise) than a known good one. With the actuator sprocket in place and the #1 piston at top dead center, it may be noted that the rear cam flat of the exhaust cam is not flat when compared with the rear cam flat of the intake cam. Upon further inspection, it may also be noted that the word Delphi that is on the cam reluctor portion of the actuator is slightly rotated toward the driver side even though the intake cam flat is flat. If this is suspected to be the cause of this concern, it will be necessary to replace the exhaust camshaft actuator again, taking care not to damage it upon reassembly. As mentioned in SI, do not force the camshaft actuator to rotate clockwise upon assembly. If it does not move easily, it is already fully advanced. New camshaft actuators are already packaged in the fully advanced (clockwise) position. This type of damage should not occur on 2005 model year and newer 4.2L engines because they are equipped with a vane style exhaust camshaft actuator, which is designed differently than the spline style actuator.

- If the timing chain tensioner had to be reset, this concern could be the result of incorrect cam to crank timing. As the timing chain tensioner is released, chain slack between the crankshaft and tensioner is eliminated. As the slack is eliminated, it is very easy for the timing chain to shift one tooth at the crankshaft sprocket without being noticed by the technician. If this occurs, it is unlikely to isolate the incorrect cam to crank timing without removing the front cover. When properly timed, the timing marks should line up as shown below once every 14 crankshaft revolutions with the #1 piston at top dead center. If all 3 of these timing marks never line up at the same time, re-time the engine by following SI procedures.

Object Number: 898507
Click here for detailed picture of above image.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Diagnostic Aids

Important: Scan tool control of the CMP actuator solenoid is inhibited when DTC P1345 sets.

The following conditions may cause this DTC to set:
• An improperly torqued harmonic balancer
• A misbuilt or mis-timed engine
• A loose or missing crank damper bolt
• The camphaser solenoid stuck open
• The camphaser stuck in a position other than 0 degrees
• The camphaser does not return to 0 degrees within 16 seconds exhibited is resolved without completing every step, the remaining steps do not need to be performed.


View attachment 72509 View attachment 72510 View attachment 72511 View attachment 72513 View attachment 72514 View attachment 72515 View attachment 72516 View attachment 72517 View attachment 72518 View attachment 72519 View attachment 72520 View attachment 72505 View attachment 72508
 

Mooseman

Moderator
Fixed 'er all up for ya! And I also moved the post about the image resizer to the support section for everybody's benefit.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Thanks Mooseman... Just an FYI for you... Thanks to your assistance ... I felt compelled to upgrade my account to Gold because if I had to actually PAY for the data you provided... my out-of-pocket expenses would have been HUGE! Such is the Value of the Collective Mind Here at GMT Nation.

Also... Because I tend to be more than a bit wordy... I researched the latest on the Rules of the Road here at the GMT Nation... I will try to pare down each of the consecutive text entries related to this repair, especially if most of the salient information can be gleaned from the images I will include with each new entry hereafter.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
"Tres Preguntas Mas..." (Three More Questions...)

1. When Decembersend pulled his broken 4.2l Engine a while ago... Was the automatic transmission still attached at the moment it was pulled?

2. Was the engine internally damaged by a thrown rod or other catastrophic failure?

3. What did he do with Atlas Motor afterwards?

I only ask because Sarasota is only an hours drive over the Skyway Bridge...
 

Mooseman

Moderator
If you want to ask something directly to a member, just add the @ in front of their name. This will send them an alert to this thread/post.

So, @Decembersend , could you answer the three questions?
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Will do from now on...
 

Decembersend

Well-Known Member
"Tres Pregunta Mas..." (Three More Questions...)

1. When Decembersend pulled his broken 4.2l Engine a while ago... Was the automatic transmission still attached at the moment it was pulled?

2. Was the engine internally damaged by a thrown rod or other catastrophic failure?

3. What did he do with Atlas Motor afterwards?

I only ask because Sarasota is only an hours drive over the Skyway Bridge...

Sorry it's been awhile since I've been on because I haven't had anytime to work on my TB.

1. I separated the Trans from the motor and lifted the TB to slide the trans under it.

2. I haven't looked at the motor other than pulling it out of the TB. My goal is to attempt to fix it if it isn't to badly damage then possibly find a used TB with a blown motor and put it in it. This will all happen after I get the TB up and running.

3. I still have the motor at my house.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
Last edited:
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
I am wondering what the complications are with swapping in 2005 Atlas 4.2L into the TB. I'd appreciate being pointed toward a comprehensive post if one exists that covers much of any changes in PCM or wiring, etc. that would be needed... or knowing if it can be done in an uncomplicated way. Can the new head I have now for the 2002 be bolted on the 2005 block?
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Also... Dorman sells an updated Intake Manifold that is supposed to do away with the need for what looks like that small gollywog elbow rubber hose that connects it to the block/head... I'm guessing it serves as conduit for Positive Crankcase Ventilation. Will that IM work on a 2002 flavor 4.2L?
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Moving on with the existing plan to replace the GM 2002 4.2L Aluminum Engine Head:

@Mooseman... It just does not get any better than this!

Please advise me if you have this .PDF already in hand or and amongst your historical work documentation. If so please let me know how to link to it so you can get the right credit, as this one is so very complete and had clear bench color photos and precise Tool Application Instructions for this entire job... AND It covers using the WEDGE TOOL that retains the Timing Chain Tensioner, without the need to remove the Crankcase/Oil Pan! One other thing... strangely, it mentions being able to replace the shoe guides too, by removing those round covers after the Wedge is firmly in place and unbolting them... So if you don't mind, perhaps you can review this documentation and let me know if my interpretation is correct.

Anyone seriously interested in doing this Epic Repair should grab this PDF NOW.... While its available, Download it and put it in a safe place for future reference.


http://ww2.justanswer.com/uploads/GMGreatWrench/2011-01-08_023933_tblazer_t-chain_part_12.pdf

I took a whole raft of images that show the measurements of the New Head Bolts and the proper Metric H-10 Male Tool to insert into the Bolt Head prior to beating on the tool in the Reverse Order of the Factory Torque Pattern for this Head Installation to get those out...hopefully with no breakage. But right now... I cannot stay awake any longer... so I will post them after I get some sleep.
 

Mooseman

Moderator
My only concern is if you replace the chain shoes without resetting the chain tensioner, those new shoes might make the chain too tight. It's now set for the old shoes with their wear so with new shoes, the chain may be too tight. And I'm not sure you can remove the shoes without removing the front timing cover, especially for that lower bolt or even the other one with the wedge tool against it. Looking at the pics in that document, you can't change the shoe with the wedge tool there.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
Last edited:
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
@Mooseman

I glommed this image from the above "Step-By-Step" .PDF and clearly shows what you explained:

The Aluminum Wedge is fully inserted on the Left Side (...delivery rod is still screwed into it but must be removed to continue head removal). It is jammed in between the Timing Chain Tensioner and the point a support bolt is positioned just above where the chain is wrapped around the Lower Timing Chain Sprocket, so as long as the engine is NOT rotated Counter-Clockwise... the Chain to Sprocket relationship will remain correct. And now I can see what you warned me about... The Right Side Chain Guide Pinion is black-bolted at the BOTTOM as opposed to being located at the Top where I thought it was... (Makes me wonder what the Hell they placed those two round ports in the front of the upper front case for in the first place?) ... and as you said... it is impossible to access that Pivot Pinion Bolt without removing both the Oil Pan/Crank Case and the entire front cover.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
In my "Follow the Bouncing Ball" process of doing this... my next mission is to install the wedge as shown above WITH THE FRONT CASE COVER INTACT and remove the V-V-T Exhaust and Intake Timing Chain Sprockets...but just to be on the safe side... I am going to use the "Chain Grabbers" as shown in the attached photos to hang on to the Timing Chain while I get the sprockets out of there. Then I will release the grabbers and guide the chain upwards until it is straight up and down...and then lower it slowly with a 2' piece of 0.041 Stainless Steel Safety Wire.

After that... My focus will shift to trying to break loose the Head Bolts using a combination of an H-10 Metric Hex Insert Socket with a sacrificial 1/2" Female to 3/8" Male Socket Adapter plugged into the top of it to be hammered on and then quickly swapped with a digital torque wrench set to alarm at very low torque increments gradated slowly until I can feel each bolt break loose in the exact reverse of the bolt-down torque sequence. This may seem a bit extreme... but if more mechanics would remove aluminum engine heads in this exact manner... they would never warp them which happens frequently while doing the unbolting at random.

I'm noting here also that even though a common 3/8" Hex Plug adapter will fit into the hollow hexed GM 4.2L Head Bolt... it is a bit loose...while the H-10 fits perfectly snug and tight. This is not a trivial matter because it means there will be a more even distribution of the force being hammered on top to loosen the bolt threads...all the way down, deep inside the block and a more evenly distributed amount of torque distributed down the shank of the bolt where the bolt will fail if it is going to do so. I have taken precise photo measurements of a New Head Bolt so I can compare their lengths and dimensions later and show the comparison for the record here on the GMT Nation TB GM Atlas Engine Forum.
 

Online statistics

Members online
9
Guests online
217
Total visitors
226

Forum statistics

Threads
19,100
Messages
574,849
Answered questions
1
Members
11,804
Latest member
Mendoza84
Top Bottom