Crankshaft removal with engine in suv

Jrp79

Original poster
Member
May 19, 2019
26
Gorgia
Its a 06 4.2 2wd tb
I pulled the pan and discovered 2 rod bearings were bad. Is it possible to remove the crank with the engine still in the suv?
Front engine plate looks to be easy to remove but the rear plate looks hard. Would it be possible to unbolt the flywheel from the converter and unbolt the flywheel from the crank and slide the crank out with out removing the rear plate.

I know i should have just removed the engine.
 

mrrsm

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Read this ENTIRE Thread... but STOP DOING ANYTHING until you have First Read Post # 55 at THIS Link ...before you get yourself HURT!


You should NOT have to remove the Crankshaft to replace the Connecting Rod Bearings if you have confirmed the presence of several Bad Ones. Focus on the work covered by @gmcman in THIS Thread to find out what you need to know to fix your issues.

The Front Engine Cover is NOT Easy to Remove... and Right Now.. You are Standing in a Deep Hole .. So the best Thing To Do is... PUT DOWN THE SHOVEL ...AND STOP DIGGING... at LEAST until you can follow the advice of @gmcman, @mc.millen and @Mooseman.

By the way...

Welcome to GMT Nation...

You ARE among Friends here...
 
Last edited:

gmcman

Member
Dec 12, 2011
4,656
Welcome!

As stated by @MRRSM, you don’t have to remove the crank to replace the rod bearings. However, if you are sure the journals are tore up then you may have to but doing this in the vehicle will be a huge undertaking, and pretty much not advisable.

One reason is....it’s heavy, but it’s not setup like many engines with separate, individual main bearing caps. The “ladder” style reinforcement doubles as the main bearing cap bolts and has to be removed as one piece..meaning all the main caps at once. This is after you remove the trans and everything on the front cover...I’m almost positive you cannot remove the flywheel as the bell housing is one piece.

Not sure if you have removed any rod caps yet, if not....What you will need is a 24MM combination wrench and use the open end to rotate the crank. Place the wrench just in front of the frame under the harmonic balancer and slip it between the fan shroud to get to the balancer bolt.

Rotate the crank until the rod bearing you want to access is at BDC. Just make sure you don’t mix up any rod caps, they can only go back to the rod they came off of....this is very critical.

Let us know where you’re at with this....we’re happy to help.
 
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Jrp79

Original poster
Member
May 19, 2019
26
Gorgia
Ive removed the main bearing ladder and all rod caps. 1 bearing is melted to the crank journal and a second has started.
Im in the process of disconnecting everything so i can pull the motor to have the crank pulled and reground. With 178k on the clock the motor seems really clean so im gonna try to do it all with out removing the head
 

mrrsm

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I'm NOT being the least bit facetious when I explain what can STILL go wrong while you are "Getting Ready to Pull The Motor". You still face some REALLY Serious Problems and the only way to UN-FUBAR your situation is as follows:

As soon as possible... Push those Pistons-Rods as far back up inside the Cylinders as they will go and then stuff Blue Scott Shop Towels around inside the bottom of each lower cylinder to protect the Cylinder Walls. Then Re-Install the Crankshaft, the Main Caps and the Cradle and then thread in the Old TTY Bolts VERY GENTLY to Re-Secure the Crankshaft back in place inside of the Engine Block.

BE CAREFUL NOT TO CROSS-THREAD THOSE OLD TTY CRANKSHAFT-CRADLE BOLTS!


You MAY still have to re-attach each Con-Rod to the Crankshaft in order to be able to Clear the Crankshaft just enough to Rotate it inside of the Engine using the Harmonic Balancer Bolt just enough to carefully Un-Bolt the Three Torque Converter to Flywheel Bolts. Leave the Flywheel alone afterwards with it still attached to the Crankshaft - Motor until after the Transmission Bolts are Removed and the Motor is Pulled and mounted on a Stand UPSIDE DOWN.

You should only remove the Radiator & Hosing, Place Cardboard in front of the A/C Condenser, remove the Wiring Harness Connections, Ground Straps and the Motor Mounts, and anything else restricting pulling out the engine, etc., such as unbolting the A/C Compressor and setting it off to one side, But touch NOTHING that involves the Rotating Assembly.

You can also clear the Low Side A/C Aluminum Tubing Line from blocking the the top of the motor by unbolting it from the Engine Lift Bracket and from the Passenger Side of the Engine. But first, Un-Bolt the Accumulator Bracket and lift it out from inside the insulation boot just enough to allow the Hose to untwist. Then use Sturdy Zip-ties in series to gently pull the Aluminum Pipe towards the front of the Radiator Upper Bracket ...without Kinking that tubing hose line... and then simply tie it snugly off in several places at the Passenger Fender Well and at the Front Radiator Mounting Bracket. Removing the Coolant Fan and Shroud beforehand makes this process easier as well.

I stress that later on... once the Engine can be INVERTED on the Engine Stand, then you can continue to perform further internal disassembly work without too much risk. In the meantime, Please... Don't touch anything else unnecessarily on the Outside or on the Inside of this Motor until AFTER the Engine is completely out of the SUV and Reverse Mounted on The Engine Stand.
 
Last edited:

gmcman

Member
Dec 12, 2011
4,656
Ok, copy that.

Well, at least it's a 2WD so the labor lost in removing the pan IMO is worth it to at least see what's going on.

With the motor out it would be tempting to replace all you could under the timing cover and also explore the possibility to remove the head. Only downside is it's very rare to remove the head bolts without breaking any of them.

One member here @mc.millen was able to hone the cylinders and go with some new pistons. With 178K miles there's quite a bit of life left, however going on the condition of the bottom end, if you plan on removing the motor then obviously the thought of exploring the option to replace the pistons has to be considered.

Would be a good time also to check for broken exhaust bolts and replace them. Even if you don't hear a leak, I've experienced first hand the detrimental effects of lowered fuel economy if the upstream sensor picks up any of that fresh infiltrated air into the manifold.

Hope the crank checks out, keep us posted.


Edited to add: @MRRSM and I were replying at the same time. To touch on what he said about protecting the bores, the cylinder walls ( liners) are pretty thin as I have learned recently, not much room, if any to perform any boring....honing at best.
 

Jrp79

Original poster
Member
May 19, 2019
26
Gorgia
Ive already reinstalled everything snug so it stays in order till i remove the motor.
Are the head gaskets prone to fail in these engines?
 

mrrsm

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Good Move... No... The MLS (Multi-Layered-Steel) Gaskets used on the GM Atlas LL8 4.2L Engines for the most part have proven to be quite reliable; with the possible exceptions of Engines enduring only the Most Extreme Abuse and/or Lack of Maintenance that would invite instances of Over-Heating.

Such events have rarely occurred when a few Owners have had Thermostat Failures and/or mistakenly filled their Water Jackets and Radiators with "Pure Agua" instead of using OEM Dex-Cool Anti-Freeze-Coolant that, unlike water... boils well above 212 Degrees Fahrenheit at Sea Level ...while water also boils at considerably Lower Temperatures in Coolant Systems of vehicles operating at Higher Elevations. Do you have any such Over-Heating problems ...besides having to deal with the more immediate crisis that you just now averted?
 

limequat

Member
Dec 8, 2011
520
Head gaskets are very good. Never heard of one failing.

For the cost of a polished crank, new bearings, fluids, and TTY bolts, you may consider a good junkyard engine.
 

Jrp79

Original poster
Member
May 19, 2019
26
Gorgia
Junk yard engines to me are no good due to u never know how they were treated.

Never over heated,always ran normal. The only issue it had was the lifter tick(i know its that cause i removed the belt and was still there). I just dont know how to test them to see what ones are bad.Also had no oil pressure at normal temp and 40 at start up but that could have been due to bad rod bearings
 

mrrsm

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@limequat 's suggestion may have to come true if the areas adjacent to the involved Main Journal Radii and Counterweights have "Turned Blue" on the Main Saddle and Main Cap areas, as this strongly indicates Very High Temperatures from the Friction involved. If the Crankshaft Main Journal you mentioned as being "Roasted" turns out to reveal a Spun Main Bearing inside of the Block, then enough damage may have already occurred to warrant Line Boring the Block.

And where these Aluminum Engine Blocks are concerned... that can translate into becoming a very expensive bill at the Machine Shop that WOULD demand that the Motor gets completely taken apart. Finding a decent Swap Motor may soon become the better option in the face of things like this. But ...First Things First... Get the motor out the easiest and safest way possible...and all will be revealed in time....and as always... Posting up some Images of what you can see ... and we cannot...would be very helpful as well.
 

TollKeeper

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Dec 3, 2011
8,045
Brighton, CO
The engines on these trucks (for you 4.2 guys at least) are so plentiful, I think I would be searching for a replacement motor. Usually you can get a whole truck for around 4-600. Something that runs but is wrecked. In your case, its what I would be looking for. Your going to spend way over 4-600 in getting the engine honed/scoped/decked and rebuilt. Then you can use the parts truck to replace whatever else you may need, interior bits, change gearing, HVAC motors, etc.

Atlanta Craigslist
2006 GMC Envoy low Mileage

And look around on CoPart.com for more. I dont know where in Georgia you are, but there are a bunch of GMT's around.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
And sell other parts and then the shell with the old engine for scrap (~$200). Keep the tranny as a spare.
 
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Jrp79

Original poster
Member
May 19, 2019
26
Gorgia
Id rather put a crank kit in, new oil pump kit, new timing kit, new lash adjusters. That way i know ill have a solid motor.
When it comes to salvage yard engines or any used engine you never know whats been done or how long it'll last. Ive rebuilt many engines but this 4.2 will be the first of this kind.
Im gonna Mic the main journals and rod ends to make sure there still true. I have all the measurements for the engine.
 

mrrsm

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Oct 22, 2015
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Of course ... You should do whatever makes the most sense... to you. But the Cautionary Tale here is that the experience many of us have had doing just that... Rebuilding the GM Atlas LL8 Motor... is quite nearly benthic at GMT Nation compared to any other resource in the world when it comes to knowing all of its difficulties and the complexity you will soon face as you tear into it... and it tears right back into you.

Obviously, nothing it seems will persuade you to the contrary, so as you go along... if you happen to come to problem areas while following your pioneering approach... let us all know if we can help. You don't make mention as to where you've acquired your information and 'Need To Know' Data... So the Question Begs... Have you perhaps been reading up on related Engine Repair Threads... here?

Even so... You should beware what follows, because unless you are Made of Money, Brimming with Much Mechanical Knowledge and Deeply Imbued with Patience... and... You are Ready to be Disappointed at Every Turn... Then you should prepare yourself for "The E-Ticket Ride of In-Line Aluminum Engine Block Re-Building". Most of the answers to whatever Questions come up... will be here... So by all means... Don't let your Pride stand in the way of obtaining Fast, Accurate and Reliable Solutions from those of us who've Been There... Done That... and Have Tee Shirts to Prove it. :>)

The Very Best of Luck and Success to You, Brother!



"When the Student is Ready... The Teacher Emerges..." Confucius
 

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