NEED HELP 06 and 08 engines

htseat2000

Original poster
Member
Jan 25, 2013
62
got a question. is there anyway to make a 2008 4.2 inline 6 work with a 2006 trailblazer? I bought a 2006 super clean white trailblazer EXT with sunroof, cloth interior, tow package, 4wd with 162,000 for $1,000.00. it had what i thought was loose timing chain, ended up being spun rod bearing. pulled engine and replaced crank, and rod bearings, and crank bearings. reinstalled engine, fired right up, but had a lifter tap. discovered one of the roller rockers was loose. I had heard a bunch of whore stories snapping off head bolts to get head off, so i purchased a 2008 4.2l complete engine for 500.00 bucks that had only 100K miles on it. got it installed, won't start. i discovered that the crank sensors are different from 2006 to 2008. is there anyway of making this engine work or am I SOL and have to remove engine and just rebuild top end of the original engine?
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
In a word, no. It's the crank itself that is different between the two. It is possible to swap the crank from the 06 into the 08 and use the 06 sensor but it's a lot of work and possibly expense if the 06 crank you have is damaged. One member did such a swap recently after basically doing the same thing as you did.
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
In a word, no. It's the crank itself that is different between the two. It is possible to swap the crank from the 06 into the 08 and use the 06 sensor but it's a lot of work and possibly expense if the 06 crank you have is damaged. One member did such a swap recently after basically doing the same thing as you did.
This is exactly correct... I still cant believe that other guy did all that extra work.

But you already have a new crank in the old engine, So I dont think your into for any extra, besides time, and gaskets really.

The horror stories you have read about the snapping head bolts is true, but they are not horror stories from all the threads I have looked at. They just snap as part of the TTY, and once the head is pulled, they generally come out with just the right amount of effort.

I do agree with you thou, I rather just replace the engine than deal with the head on the 4.2.
 
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Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Since the 06 engine was basically running with lifter noise, I would look at fixing that which shouldn't require pulling the head. Lifter scan be replaced with the head on. Even if the cam was also damaged, it can also be replaced without pulling the head.

Pulling the head can be done but I would still rather replace the whole engine if that would be the case. It can be done but is a nightmare if you have multiple bolts that break.
 
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gmcman

Member
Dec 12, 2011
4,656
Yes, the lifters or "lash adjusters" can be replaced without removing the head. You will need a momentary push button for the starter to rotate the engine, as well as the Kent-Moore EN-47945.

KM1.jpg
 

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