need help:8.1 gas to a 6.6 Duramax. .

[carznmore]

I have a 2002 chevy 3500 pickup originally equipt with a 8.1 gas engine with allison trans. . i just recently install a 2002 6.6 duramax with allison trans. . im getting the engine to turn but not fire over and run . .i primed the pump so i believe im getting fuel. .i used my stock interior harness and the engine harness from the duramax is there anything needed or that im missing that anyone is aware of? any help is greatly appriciated!! thanks

[More Power]

You may need to perform a "password learn" procedure. Because the vehicle ECM was changed, the Passlock II security system may be confused.... ;)

Jim

[carznmore]

And how would i go about that? lol . .Thanks!!

[More Power]

A Tech II Scan Tool can do it in just a few minutes, or you could use the 30 minute procedure found in the service manual. In either case, this procedure allows the BCM and ECM to learn the Passlock code in the ignition lock assembly. :)

Jim

[91dually]

I know your post is old, but I just found it. I have an 01 3500 dually with the 8.1 and have found almost no information on a Duramax conversion. Can you share experiences and costs? I would think the 3500 which could have come with the diesel might be easier to swap. Any help is appreciated.

[More Power]

While I don't have all of the details, I have pondered the question of what needs to be done to replace an 8.1 with a Duramax...

There may be other needs, but here is a list of what may be essential once all of the diesel hardware has been installed (engine, intercooler, possibly radiator, and other misc diesel bits).

1- Engine and transmission wiring harnesses.
2- ECM/TCM
3- Diesel fuel lines and fuel tank's diesel sender package/fuel cooler.

As mentioned earlier, you'd then need to perform a "Password Learn Procedure", to get the Passlock system acquainted with the new ECM.

I don't know whether the diesel instrument cluster would "have" to be changed, but it might if there's a different set of display phrases incorporated into the cluster's DIC. If you're not worried about complete display compatibility with the cluster, I imagine the gas cluster would otherwise work fine. Personally, I'd get the diesel cluster for the "diesel" identified fuel gauge and correct tach scaling.

Jim

[91dually]

Thanks. I do understand the basics, (engine, trans, transfer case, exhaust, fuel systems, radiator), the things I was looking for are engine mounts, electronics, (how easy is it to plug into the oem wiring, as the truck did have the diesel as an option), changing the rear to a 3.73, will my Allison work as is with a Duramax, (or does it need to be reworked or even is the same model), etc. Removing an engine/trans and reinstalling is OK, but fabricating new parts and mounts takes a little more than I want to get involved with. Also I am seeking general advice as to costs, (beyond the engine/trans), the small pieces are really add up. I would think, and I am looking for verification, that swapping in a 3500 would be much easier than stuffing a Duramax into a Tahoe or Suburban. Lastly, what about inspections? How much trouble will one get into with their DMV? I spoke to one retailer of Duramax engines, they would not even sell me an engine as the truck did not come with one.