an I put an 04 5.3 LM4 into 05 LH6

ChevyShawn

Original poster
Member
May 2, 2017
4
Terre Haune, In
My 05Trailblazer has a 5.3 LH6 engine that has a collapsed DOD lifter. I have a friend that has a 5.3 LM4 out of a 04 Trailblazer. Can I trade these out, If so what all does it intell or should I just do a upper end DOD Delete on my origional engine

Thanks in advance
Shawn
 

Reprise

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Jul 22, 2015
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I think you could. You'd need the PCM from the TB, for sure. In '05, GM moved the transmission programming to a separate 'TCM' (attached to the outer trans case.) That's something the '04 PCM wouldn't know about - it has the trans mapping as well as the engine controls in one PCM. So, if you do it, it might (?) be best to swap as a full engine / trans combo. But the trans is essentially the same between both, except for what's controlling its programming.

The LH6 was among the first of the '4th-gen' LS engines; the LM4 was among the very last of the '3rd-gen', with the attendant differences in both. The main difference was the DOD capability (there are others, but I'll not detail them here - easily found elsewhere.)

I don't know of anyone who's done a swap of this type. If I were to guess, I'd say it might require removing the front side of the truck (grill, bumper / fascia, along with the hood, rad / fan, etc.) But you can probably leave the fenders in place.

Which would be easier? Probably doing the DOD delete, especially if you know your way around the engine.

Depending on what your friend is charging you for the LH6, coin flip for 'cheaper'.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
I would think that you could do it but keep the '06 PCM, TCM, fuel rails and possibly the intake. You will have to get the PCM tuned to delete the AFM. Might as well go with a full PCM and TCM tune.

I've done both types of the work you are contemplating. I did an engine swap (albeit an I6) and the DOD delete. Work wise, I think the engine pull is more work, especially with the front diff, axles, crossmembers and rack & pinion to contend with. The I6 is a long and tall motor while the V8 is shorter but wider.

I think it will come down to cost. A DOD delete is ~$1400 for all the parts plus the tune. Mileage might also come into play depending on which one has less mileage.
 

Reprise

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I knew I shoulda held back and let someone else more knowledgeable answer first! D'oh! :duh:

$1400 USD for parts alone...geez.
If I ever get one of the early DoD motors, putting in a tune would be 1st thing I do, even before changing the oil. (ok, maybe a few things while I'm waiting for the PCM, but you get the idea.)
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
That's what I've seen recently but I think they were upgrading to a performance cam and valve springs.

Texas Speed's kit comes to about $565 with all new valve lifters, cam, cam gear (3 bolt), valley cover, head gaskets and other ancillary parts, but doesn't include a new oil pump (recommended, high volume/high pressure), timing chain, intake gaskets, valve cover gaskets, valve stem seals and other stuff. Probably gets close to $1000 plus the tune ($99 at LimeSwap)
 

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