Changing Cylinder head

[MrGiggles]

05 Chevy Trailblazer 4.2l with 192,000 Miles-
This is a project I'm doing with my son before he goes to vocational school for auto mechanic in my garage so he can get a feel if this is what he wants to study auto repair. I know basics like changing stuff fuel pumps, water pumps, gaskets etc.

Did wet and dry compression test results:
Cylinder #1: Dry =170 -=- Wet =180
Cylinder #2: Dry =179 -=- Wet = 180
Cylinder #3: Dry =60 -=- Wet = 62 (oil in cyclinder and on spark plug?)
Cylinder #4: Dry =0 -=- Wet = 2
Cylinder #5: Dry =170 -=- Wet = 180
Cylinder #6: Dry =160 -=- Wet = 170


We watched this video which helped us see your some of the adventure we have a head of us

Questions:
If I purchase a re-manufactured cylinder head from for $455.00 and new gasket set will this fix the compression issue?

Can any one direct me to were I can download a PDF or instructions on changing the cylinder head with bolt torx settings.

Also my main concern is is resetting the timing correctly.

Any instruction links, Video links and advice is greatly appreciate

 

[mrrsm]

Not necessarily...

You would help our understanding if you could describe the circumstances leading up to this problem... as in ANY and all Performance Symptoms... and describe any prevailing Engine Noises that you may have heard going on. Believe it or not... It is entirely possible that this engine could keep on running... albeit while making an AWFUL lot of Racket...as long as any shattered Piston pieces and or the Connecting Rod did not bend and jam sideways into the Cylinder Wall. In some cases... the Con-Rod(s) can get bent, turn sideways and shatter the engine block right through the cylinder and side walls and essentially ...Grenade your Motor.

The "0" Compression MIGHT be caused by a Bent Valve ...but it is equally possible that the Piston Head could have been compromised due to Seized Pistons Rings. Using an inexpensive USB 7-9MM Boroscope would reveal whether or not the Piston has been damaged... either by a Collapsed Valve or from any Stuck Compression Rings Popping the Piston head off like a Bottle Cap from an RC Cola. This visual Inspection would be the NEXT thing to do before you purchase any Parts or Tools or loosen any fasteners until you know what is actually happening down inside of the #3 & #4 Cylinders. This is my Thread that will edify you on what to do...and NOT do... during this Repair... and hopefully... it may dissuade you from attempting this repair:

https://gmtnation.com/forums/threads/the-85-000-00-gm-4-2l-engine-repair.14423/

Unless you are a Very Experienced Mechanic with Deep Pockets and Patience... and want to incur this self-inflicted wound on purpose to "Follow The White Rabbit" Down inside of a VERY Expensive Bottomless Money Pit... Save that Money you were thinking of using to buy that Engine Head... and put it into a Mason Jar marked "Swap Engine Money". By the way... a Properly Re-Built Engine Head runs around $750 with a (3) Year Guarantee... and even if you were frugal and careful in the buying of ALL the Parts and Pieces you would need to do this job... count on spending a Minimum of $1,500.00... or more.

The link below is one of many Photo-Albums available for you to look over to visualize what my own experiences have been with this complicated R&R. As mentioned above... I memorialized how all of this work gets done in that Tome that rivals the thickness of a Tokyo Phone Book.. However... your Better Bet is to listen to the Advice of @m.mcmillen and @Mooseman on the CLIFF NOTES versions of this R&R should you decide to proceed. I'm suggesting now that if you discover that the #3 & #4 Cylinders are Damaged or you find evidence of fractured metal residue in your Autopsy of your Oil Filter... to find a decent, Low Mileage Engine out of Wrecked Vehicle; either an Envoy, Trailblazer or Buick Ranier... and go that route. To do otherwise would be a waste of your Time, Energy, Money... and your SANITY. Again... Here are the Images I took of this Mechanical Nightmare:

https://www.flickr.com/photos/126111508@N07/albums/72157695921930542

 

[Mooseman]

Head replacement is not a trivial job on these and not a good platform to learn on. Some reasons for this:
- head bolts WILL break in the block, usually in the most inaccessible spot, requiring special (read expensive) tools to get out
- timing chain retention from falling into cavity and/or preventing the chain tensioner from extending
- high possibility of failure if timing chain and gears not timed properly

How have you confirmed that the head/valves are responsible for the low compression? You have two adjacent cylinders with low compression. Could be a bad head gasket or cracked block. You need to confirm with a leakdown test.

Have you looked up the actual procedure? Manuals are available to download in my signature.

That video was awful! These are better except he didn't properly hold the chain to prevent the tensioner from extending. He should have used a wedge tool instead as per the manual. And he also broke 10 of the 14 head bolts.

Probably for the cost of machining the head, new parts and gaskets, it would probably be cheaper and easier to just swap the entire engine with a good used one or, if your finances allow and worth the value of the vehicle, a rebuilt.

 

[MrGiggles]

I'm ordering an leak down tester tonight.

My son left me a note he broke a bolt on the intake manifold second row from the front of the vehicle when torque it changing the fuel injectors before he left on his hot date. I can hear a sucking sound but don't think that could effect the compression test? It's at the bolts between cylinder 1 and 2.

History of the vehicle It was sold to us for for $250. I drove it home it had a cylinder 2 misfire changed the plugs and all the coils. The code for the cylinder 1 misfire left now get a P0300 code and a gas gauge code because the gas gauge did not work stuck on 1/4 tank. So we changed the fuel pump fixing the gas gauge.

Before all these repairs the engine run good with but ruff idle and very ruff at stop signs in drive holding the break down. Then its started to run ruffer to the point no power and wanting to dye when stopped and in drive with power loss. Figured the fuel pump was crashing so we changed it. Did not fix it the P0300 just fixed the gas gauge issue. So we changed all the fuel injectors. Runs better but still ruff with brake down and drive almost wants to die. In park hold the gas to the floor RPM's will not go over 3900 it hesitate acceleration and when idling runs like a steam choo choo trail best I can explain it.

We changed the oil filter and coolant. The coolant looked and smelled normal and oil filter had no sighs of metal shavings. The oil did seam to gas a gas smell.

Last changed the water pump and thermostat. Have noticed a light flicker but think that's caused buy the the ruff idle. Took it to Autozone they tested the alternator and battery and said there both running good.

Question: If the intake manifold is bad could that cause these issues or the throttle body?

We did clean the intake manifold because it was very gummed up used oven cleaner and power washed it then let it dry like a friend told me he did his and had to replace the hose on the intake manifold it was brittle use hose clamps and 1/2" hose plus made sure it has no kinks and good air flow the old one was brittle and broke a part.

The motor has 192,000 miles.

Our budget is not great but I have the time to help my son since I'm stuck at home fighting neck cancer but winning the battle just went into remission so I will take all the time I can with family. Getting cancer give you a whole different out look on life.

Is there a video format I can up? Tried mp4 did not work. Have video of the engine and how it sounds.

Hope that helps.

 

[MrGiggles]

Also my last ODB2 Scan results
Getting P0300 and P0068

After putting it to gather and installed the fuel injectors

 

[mrrsm]

You'll have to forgive me if I pay you the compliment of being so BLUNT... but BOTH of you are already standing in a Deep Hole and making the mistake of handing each other The Shovel if you continue working on this Engine and affecting repairs... without using the procedures of RTFM. The First Example demonstrating this problem was the accidental Breaking Off of an Intake Manifold Bolt that ordinarily should NEVER receive anything more than 89 INCH Pounds of Torque anywhere along the IM Flange.

As a result... now the original problem of performing whatever was being done is further compounded by the need to Extract The Broken Bolt Fragment and then to find an almost impossible to locate replacement of the Broken Trapped Fastener to repair the IM. This translates into the need to completely REMOVE the Intake Manifold all over again in order to have enough "Elbow Room" and Hand & Tool Access in order to perform this Broken Bolt Extraction.

And that leads us to the next, MUCH MORE SERIOUS example of a much more immediate problem. It was NOT necessary to use ANY Harsh Cleaning Chemicals to Clean Out the Intake Manifold interior or any other Grease Soaked Plastic Component such as the Intake Resonator on this LL8 Engine; No matter HOW Gunked up with Oil and Dirt they happen to become inside. You would have gotten BETTER results from just filling it (them) up with Hot Water Mixed with Blue Dawn Dish Soap and let its soak for a time...and then hose them out with Fresh Water and let them Air Dry in the Sun.

You MUST remember that Caustic Soda (AKA ---LYE--- or Sodium Hydroxide) may indeed be the 'Bees Knees' for its use in a Cauldron of Boiling Water to De-Grease a Cast Iron Engine Block... But it has Absolutely NO Business Whatsoever being applied to use ANYWHERE either ON or INSIDE of the Components, Plastic Air Moving Fascia, External or Internal places on or within GM LL8 Engine.

If the slightest amount of this stuff got ingested into the Engine Cylinders after you performed the IM Installation with ANY Sodium Hydroxide Residue left inside... it could have migrated down inside of Cylinders #3 & #4... and PARTIALLY DISSOLVED THE PISTONS ENOUGH TO CAUSE THEM TO SEIZE UP INSIDE OF THOSE CYLINDERS. If the Compression Loss Issues in Cylinder #3 & #4 became Evident AFTER the use of the Caustic Soda Cleaning... then THIS Cause and Effect correlation would explain how the problem occurred.

THIS Video demonstrates Why The Use of Caustic Soda when cleaning ANYTHING that comes into direct ...or indirect contact with this Aluminum Engine (Aluminum Pistons ... in particular) is a Very Bad Idea:

These further explanations and images from THIS Link should incline you to proceed from now on by using more research, forethought, and an abundance of caution prior to taking any more actions with Chemical Products that will wind up becoming another Self-Defeating, Exo-Thermic Disaster:

http://www2.uni-siegen.de/~pci/versuche/english/v44-10.html

The P0068 is probably a just direct response to the Massive Vacuum Air Leak that is present as per that "Sucking Sound" you heard after the Intake Manifold Lost it's Vacuum Seal courtesy "The Broken IM Trapped Fastener". As soon as you can... Please obtain the Digital GM Manual... and tomorrow ... Sit down with a Cup of Coffee in the Light of Day with your son... and Bone Up on Things.

 

[TollKeeper]

I would have to agree with the members above. Using this engine for a "learning experience" is not something I would suggest. It would probably be easier to just replace the motor in my humble opinion. And judging by your compression tests, my opinion is it -Might- fix one of the cylinder compression, but not the other.

Used engines are on ebay, complete, for less than your head that you mentioned above. They range from 400 up to 3500 (new engine). And I am sure if you search on ebay, and locally, you can find one that will be complete, and put in less time and money, than replacing the head on that engine. Just be sure to search for ones that include free shipping, or are local to you.

Edit: I would also like to add, if you do decide to replace the engine, I would suggest finding one with the exhaust manifold still attached. There are so many threads on the forums here about sheared off exhaust manifold studs...

 

[Mooseman]

OK, this added info does change things A LOT.

If you have one, use a boroscope to inspect the cylinders for visible damage. Either the pistons or the cylinder head near the valves may have been damaged. The intake manifold may have suffered damage and may have passed down to the cylinders.

As indicated above, I still stand by my recommendation to swap the engine with a good used one, which should come with its own intake manifold. Try to get the throttle body with it as your current one may be bad. Check your exhaust manifold for cracks and if the engine comes with one, inspect that one too. Keep the new parts you installed as spares or use them. Given the age, mileage and value of the vehicle itself, this is the most cost effective measure. Additionally, an engine swap is doable without special tools or expert knowledge. I just found there were a lot of electrical connections to mark/document and the front differential and axles to deal with, unless it's a 2wd. That would be a good learning experience.

 

[MrGiggles]

Thank you for everyone's advice and honesty.

I agree with everyone were going to do the engine swap and stay sane.

I was told that this engine it's common for cylinder 3 - 4 to have valve issues is this true?

There seems to be a lot of these used engines on the market for sale don't know if that a good thing I guess they have been used in a lot of vehicle like envoy.

Thank you for the links that will help Mooseman.

Well the next step I we need to learn is how to remove the air conditioning Freon and refill it again after the swap the engine something I have always wanted to learn how to do.

Any links on the forum that I can read to help learn how to work on the air conditioning system. I have a friend that can loan me his gauges and vacuum pump.

The bright side it's a 2 wheel drive!

 

[Mooseman]

Evacuation requires the actual machine. Best bet would be to limp it to a shop. They usually do it for free since they are getting free refrigerant. There are lots of videos on YT on how to vacuum and refill it yourself but you would need a vacuum pump. There are cheap ones at HF and Amazon that should do the job. Same for the gauge set.

 

[MrGiggles]

Thank you Mooseman

Didn't think of that I will call the shop down the road see if they will remove the Freon and later refill it for my save a lot of headache for us would be worth it and can focus on the swap.

I'm talking to a Wrecker Salvage service in town that has a 05 chevy trailblazer 4.2l engine in a wrecked vehicle with rear end damage that runs great wanting for a call back when I can see it. It has 155,000 on it and wanting $500 + $100 delivery for it doesn't sound bad especially if I can hear and see it running.

Wondering do you know the Freon type the 05 trailblazer takes I pry its not the old expensive stuff and how much it takes?

Just found that info if it's correct
front and rear A/C 48 oz
front A/C 29 oz
R134A

 

[TollKeeper]

Sounds like a decent buy if you can hear it run. Make sure the engine is cold before they crank it, watch exhaust for any type of smoke, and listen to the valve train, any type of rattle could be a cause for concern, Although the 4.2 doesnt normally rattle, they just go from being a good engine, to "what just happened". Check oil level also before starting it.

 

[MrGiggles]

I will Thank you

 

[Mooseman]

It uses the newer R134a so no problem there. The old R12 hasn't been used in vehicles since the mid-90's.

Sounds like a decent buy if you can check it out first. Look at the oil for evidence of water and if possible, do a quick compression test. Be sure it comes complete with both manifolds and the throttle body.

 

[MrGiggles]

Strike 1 - That engine had water under the oil cap. Then he tried to sell it to me for $300 if I pulled it. Told him nope. I think he just changed the oil. Won't deal with that guy again.

If I find one online is that to big of a risk?

Did a quote on swengines they have a 4.2l for $1,345.00 + $75 residential with 5 Year 0r 50K parts and labor warranty really streaking my budget.

Specs:
Vehicle:2005 Chevy Trailblazer EXTPart:Engine - 4.2L (VIN S, 8th digit)Price:$1,345.00 (Used Engine)5 Year or 50k Mile Parts & Labor Warranty includedShipping:Free Shipping (all U.S. states except HI & AK)
(*There is a $75 charge for all residential deliveries)Mileage:~80K milesNotes:-We Deliver Low Mileage Used Engine Nationwide Daily!-

 

[HARDTRAILZ]

Water under the oil cap causing milky residue is common if cold out on these. Seems every fall we get a swarm of people saying they have white under the cap. Was it water water or the milky mix?

 

[TollKeeper]

Personally, I think thats overpriced. Its not complete, looks like most all the sensors have been stripped off, which means either you have to use your old sensors, or buy new ones, plus you have to remove and install...

Where do you live again?

Edit: And on that engine, if thats the one they deliver to you, I already see a problem, theres at least 1 exhaust manifold stud broken.

 

[Mike534x]

My first 4.2 and my current Envoy (5.3) always usually have a "milky residue" from not being driven long enough to warm up. I wouldn't worry about that, though I had the pleasure of dealing with an idiot mechanic who said my engine was full of sludge because that little "gunk" isn't common.

$300 doesn't sound like a bad offer for the engine from the salvage yard, especially if he knocked $200 off the price. If it sounded as it should, and there really was only the milky stuff under the cap then it sounds like too good of a deal to pass up. That's of course he wasn't trying to pull a fast one. If you have a local LKQ you can try checking with them to see if they have any engines available, most of the ones I've come across still leave some of the sensors and other accessories attached to the engine.

 

[MrGiggles]

It was milky a lot of it if he tried to hide it he forgot to clean the cap and on the dip stick seen some milky colored oil after he ran it. As far as cold start he had it running when I got there.

To cheap and I could have talked him down more but seemed very shady and done need to buy a piece of junk.

He keep saying it's a AS IS sale seemed shady. A little hair in the back of my neck said avoid this one.

I wonder if it would be better to get that engine I posted a few post before or similar it has a 50K 5 year warranty on parts and labor if it doesn't work after we put it in we can have a shop do it and wont have to do it twice unless we want to. Engine has 80K on it.

Not sure what that part is I circled in the image I think it's a gmc part?

I live in Ardmore Oklahoma about hour and a half from Oklahoma city and the same from Dallas Texas. I do have a trailer and a friends truck I can use to pull it if I have to go get one as long as they can load it.

Prefer to drive in Oklahoma city

 

[TollKeeper]

Hey forum members, is there a reason when I search for his engine, it says its a 05 only year? That doesnt seem right.

Craigslist Trailblazer Engine

Might be worth checking into...

 

[MrGiggles]

Thank you tollkeeper looking on Craigs now.

My son has a good point he said were going to pull the engine any way so after we get our leak down tester and complete the test might as well pull the engine and see if it's only the cylinder head or if the block is bad and see if it can be fixed first. I think he wants to pull it apart

Go get the Freon out and put it in the garage I guess it couldn't hurt while motor searching. Won't tell him but still going to do a swap engines if I find a good one and would be easier taking it to the salvage for junk metal in pieces.

 

[TollKeeper]

It would be a good learning experience to pull it apart the old and busted... Showing him where it failed, and maybe even finding out why it failed where it did. Its always fun to do that, especially when you dont have to be gentle about it, since you arent going to put it back together, or in the vehicle.

That being said, there are alot of these engine available down towards Dallas on Craigslist. But few offer mileages. This salvage yard offers the complete engine, pulled for you, for 450 bucks, with a 60 day warranty. Since the wreck happened in the front, I would assume it was running when wrecked... But the question I dont know the answer to is that its an 02 model. What has to be done to covert it to a 05 drive train..

Another CL ad

 

[MrGiggles]

Good question. The good thing is I'm in no rush.

Also a few minutes ago calling I found a salvage in Oklahoma city I'm going to go up there Saturday morning and take a look at them they have 3 of them for $500 + $75 core charge that all have less than 120K. 2 of them are roll overs and 1 if a side collision totaled vehicle.

I will update what I find after I see them run and check them. They all come with intake and exhaust manifolds, throttle body everything except the ECM ($45.00), alternator, a/c pump, power-steering pump, turbo if had one etc. Comes with 90 day warranty 35K miles.

I will update what I find I have to visit the Cancer doctors and let the vampires have some blood tomorrow so not sure if I post tomorrow. My son ready to go motor shopping lol! Teaching him not to jump on the first thing we find check it out first. Every ones tip will help me select a good engine thank you.

I will call that guy for that first motor I looked at maybe if I don't find something take a second look and tell him I want a cold start this time and compression test.

 

[mrrsm]

@MrGiggles... As you go forward...You and your son... are Brothers to us ALL here now... and if you consult the Members about whatever is on your mind(s) ... They'll gladly respond to offer ideas, suggestions and all the Help you might need... hopefully BEFORE you embark into doing anything that is unfamiliar to you both... and THAT...is "No Laughing Matter..." :>)

 

[Mooseman]

02 to 05 motors will work. The part you circled is the SAIS (Secondary Air Injection System) which is on 04+. The only one that will be different is the 02 which had an oil level sensor in the oil pan, which was deleted in later years (another GM cheap ass move). You could leave it in there and wire a light up separately.

Yeah, if it was also milky in the stick and no warranty, you did good passing on it. At least you'll know what to look for while shipping

 

[MrGiggles]

I know it's good to try and find the source of the engine damage if you can. I just got off the phone with the guy we purchased the truck from see if we could figure out some thing. He told me the trailblazer over heated on a trip his dad took in it to Ohio and drive it back with a bad thermostat having to stop and let it cool every so often to get it home and he put a new thermostat when he got back home. Which I believe is true because the thermostat did not look very old when I changed it any way and noticed all the hose clamps were GM factory except for the one on the thermostat hose.

Maybe the head gasket issue but personally never heard of a head gasket causing a compression loss but guess it could happen.

We still going with the engine swap because don't know if the motor is warped or cracked? I got a leak down tester in the mail I ordered the auto stores are all 30% higher for almost everything and no hurry.

Still going go a head with the engine swap. Personal I would not know if the block is warped or cracked.

Good night everyone

 

[MrGiggles]

Update: Purchased a 4.2L engine with 98K on it that was in a roll over and I was able to see running great and had no issues or signs of damage or problems. There pulling it now comes with intake and exhaust manifolds Yah! There delivering it for $175.00 to my house and will unload it into my garage worth the money to me considering it's 98 miles from my house. Paid $500.00 for the engine there also giving me the alternator , throttle body, plugs, coils and ecm with it. Plus 6 months 50K warranty for replacement without labor.

I got the terms in writing on the receipt.

Should be delivered three days.

Want to thank everyone for there help and when I can I will become a member I know I will need more help on they adventure.

As far as my cancer test and labs still in remission they gave me 90% neck cancer will not return.

 

[m.mcmillen]

It sounds like you got a good deal on that engine!

Good to hear you're in remission too. Good luck with your engine swap.

 

[TollKeeper]

Sounds like your heading down the road to better health, and a running truck! Congrats!

 

[Mektek]

Glad you avoided the nightmare and finally got to the best solution

 

[Deleted member 20902]

Hey forum members, is there a reason when I search for his engine, it says its a 05 only year? That doesnt seem right.

Craigslist Trailblazer Engine

Might be worth checking into...

The only thing special about the 05 engine is the return less fuel system + 24x reluctor. The long block itself is compatible, just have to swap the fuel rails. Prior to 05 they had return systems and an external fuel filter. I just put an 2005 engine into a 2004 trailblazer a few months ago.