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post #1 of (permalink) Old 01-17-2018 Thread Starter
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Engine swap: 3400 to 3800

Hey what's up guys, I just bought a donor car for my 2005 impala base model. The donor has the 3800 and is a 2000 LT. Just wondering and needing a little guidance on all that I need in order to make this swap successful? The 3.4 is knocking real bad and the donor I picked up has a rebuilt trans and the engine only has 64k miles on it. HELP
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post #2 of (permalink) Old 01-17-2018
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Wow, that is an ambitious undertaking. I am sure it can be done, but probably beyond the skill set of many an average DIY mechanic. Kudos to you if you have the ability to pull it off.

Not having done such myself, a couple of things I'd be looking at are:

Definitely need full OEM shop manuals with wiring schematics for each car.
Will you have the same number and orientation of electrical connectors? (there may be a lot of soldering in your future)
Difference in weight and mounting points of new vs old powerplants?
Any need to change suspension components to accommodate drivetrain swap/weight change?
Swapping-out all ECM, BCM and any related brain boxes (if the connectors are the same)
Does the 3.8 require a higher output fuel pump?

Just my initial thoughts.
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post #3 of (permalink) Old 01-17-2018
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Originally Posted by 2014LTDLTZ View Post
Will you have the same number and orientation of electrical connectors? (there may be a lot of soldering in your future)
I think the key here is that the donor car should have all the correct wiring harnesses and computers (PCM, BCM, etc) so whichever ones are necessary can be moved over with the engine/trans. It will be a lot of work, but substantially easier than modding underhood harnesses for the 3.4 to work on the 3.8.

That said, it's still a heck of an undertaking.

I suspect, but cannot state with expertise, that some re-programming/re-configuring of the computers (donor and/or target) may still be required to make everything work smoothly. For example, there may be some accessory or feature in the donor car (such as cruise control) that's not in the target car and thus may need disabling in one (PCM) or more (BCM) computers.




If your socket set is all the same brand, you might be a city slicker.


Last edited by plano-doug; 01-17-2018 at 08:15 AM.
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post #4 of (permalink) Old 01-17-2018
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If you have a complete, better optioned, donor I'd just move the whole deal over. Who cares what the BCM and ECM figure the VIN # is they match the key and the rest of the parts... The odometer will match the drivetrain too and you can state that honest fact if you ever sell it.

Back in the late 1980's I bought a 1983 Subaru DL1600 hardtop with a trashed interior and transmission after my nice low miles 1984 GL1800 hardtop got T-boned.
I stripped the new chassis right down to a bare weathertight shell did some body and paint work on the bare bare shell and then moved the clean everything over from the 84... one piece at a time... now where have I heard that line before?

I ended up replacing some RH front suspension and the steering rack, rad support, grille, RH headlight buckets, RH weatherstripping, and hood from a second GL donor and installing fresh brakes, undamaged wheels, new struts, and new tires but that was the extent of the extra parts needed.

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"Speed never killed anyone. Suddenly becoming stationary... that's what gets you." Jeremy Clarkson
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post #5 of (permalink) Old 06-16-2018
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I'm currently in the process of doing such thing. Still looking for info if anyone has anything.
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