6.5 Engine Swap-1994 to 1995-Any Hidden Problems?

[bubble-city]

Hello,
I am planning to swap engines this weekend. Before I do, I thought it a good idea to check with all of you. I have a 1994 engine that I am putting in a 1995 truck. The replacement engine is complete, including turbo, manifolds, wiring harness & computer. Are there any compatability issues that I need to be aware of before I start? My thoughts were to install the engine using the attached wiring harness, to prevent mis-wiring and save some time, but the old computer so that it matches the truck. Will the '94 injector pump work correctly with the '95 computer? If I have to use the '94 computer, will the transmission be affected? Also, I have read a little about these engines having to "re-learn" TDC. Will this be an issue, since the inj pump and crank have not been separated? Any tricks or tips to make the job easier?
Thanks, Mike.

[john8662]

The 94 and 95 engines are almost identical, wiring should be exactly the same on the engine. You can leave the injection pump wiring harness in the V of the engine and just plug them into the existing truck harness.

Are both of the engines the same, S or F 6.5? If they're both Vin F engines (hd non egr version) then it should be a smooth transition.

What is the truck?

You might run into trouble if the 94 engine has a 5068 or 5067 IP on it, any other model IP won't give problems.

[bubble-city]

The truck is a GMC 3500 crew cab dually, with the "F" code engine. I am not sure of the VIN code on the '94 engine, but it does have an EGR valve under the plastic top trim. The inj pump has a sticker under the metal tag that reads "5521 11/06/00".

[john8662]

Uh oh, You're swapping in a LD 6.5 into a truck that had an HD 6.5 in it.

It will work, you'll need to swap intake manifolds for sure. The 5521 pump will be compatible with your '95.

The main difference in engines at this point is internal, slightly different heads, containing smaller pre-cumbustion ports.

Everything else should work on the '94 engine.

[bubble-city]

Thanks, I appreciate the info. I had figured on changing at least the upper intake plenum to eliminate the EGR valve, so whats a few more bolts. Just makes the swap a little slower! Compatability with the pump was my main concern, so not having to swap them is a big relief. Since the pump & crank sensor haven't been separated, will I have to deal with the TDC "re-learn" process? Or does separating the engine from the computer require this?
Mike.

[diesel65]

Yes, You need to do the TDC Relearn because the computer has not been matched to the donor engine. The relearn should be done whenever you take apart the front of the engine, including when just replacing the crank sensor or swapping an engine, it does not need to be done when you do just an injection pump.
Speaking of crank sensor, since you have the engine out, I would strongly recommend that you replace the crank sensor as a preventive measure. The 96' and up engines needs to have the power steering pump moved to replace the crank sensor, I am not sure how much room is behind the 94-95 p/s pumps.
Just to clarify on the intake manifold, you need to replace both halves, the upper and the lower to remove the EGR system.

[bubble-city]

Thanks. I was going to replace the water pump & timing set before installing the engine. Changing the crank sensor sounds like a good idea while I am there. Especially if I would have to do the relearn process over if it went out. As far as the TDC relearn is concerned, can you direct me to some info on this process? I searched the forums, but would like to understand what all is involved.
Mike.

[bubble-city]

Hopefully, I will get my engine swapped over the weekend. Once it is together, is it safe to drive, and/or will it run, before the TDC relearn process is done? I have a GM mechanic that has the proper tool and will do it for me as a side job, but won't make "house calls". I would rather drive it to him rather than have to trailer it.
Mike.