lly inplace of lb7

[randy85]

ok uys i have a c55000 had a lb7 in it i want to put a lly motoor in and am having trouble with the injection system has naybody done this conversion and have some advice ??? i have oth complete trucks the lly coming from a 2006 gmc 3500

[THEFERMANATOR]

What year is your C5500? Most likely the easiest way to do the swap is to do the whole engine and harness up to the underhood fuse panel where it all hooks together. The connectors from 03-06 are pretty universal and easy to swap between generations. Swapping to an 06 though can cause some issues though as 06 was the first year of CAN BUS for the OBD II communications. It could cause some issues with the BCM communicating. Also since you say it is an 06 you will also need the TCM to work with the ECM as 06 ALLISONS used the GEN 4 TCM VS the 1000 series TCM of 01-05.

[More Power]

The easiest way to get the new engine in would be to use the LB7 heads, injectors, fuel rail, injection pump, and turbo. Then the LLY would become an LB7 for all intents and purposes.

Otherwise, like was mentioned earlier, you'll need a complete electrical/electronics swap...

Jim

[randy85]

ok so the lly motor was already in the 03 c5500 when started this post i have both complete trucks what components do i need from the o6 3500 hd to make the lly motor work in the 2003 c5500 ? i will check the build date on the 06 to see if it was built in 05 which makes a big difference im guessing i doubt im that lucky

[Mark Rinker]

What engine componant failed on the '03 5500?

What MP is saying is BY FAR your best approach. Forget the electronics swap, re-wiring, etc. - view the donor engine as a 'short block', re-using all the LB7 specific parts, which include head, injectors, IP, ECM/TCM, turbo, etc. from the '03...

Better yet, keep looking and find one of many low mile or crate (complete with new turbo, IP, etc.) LB7s out there...

http://cgi.ebay.com/ebaymotors/GM-Duramax-6-6-Turbo-Diesel-engine-LB7-4500-5500-60K_W0QQcmdZViewItemQQhashZitem53db4d2c1eQQitemZ36 0161553438QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcce ssories

[More Power]

What Mark said....

I might be inclined to make the swap to the new stuff if there was a compelling reason, like doing it just to show it can be done, and to write about it.

Moving all of the 06 stuff to the 03 truck is the easy part. Troubleshooting glitches (minor incompatibilities) could be time consuming and it could require having the electrical wiring diagram books for both trucks. I would transfer all underhood (except lighting) wiring harnesses and the electrical center, all under dash wiring harnesses and fuse/junction blocks. You may also need the steering column and related wiring harnesses, HVAC, and other dash electrical control panels. You'd be essentially making the 03 an 06. Trying to meld the two systems is where incompatibilities could show up.

Jim

[THEFERMANATOR]

In a regular GMT-800 truck this swap wouldn't be that bad, but I don't know about a 5500 series truck. There only one person I know of who may be able to help you out, but he is pretty busy. His screen name is duratothemax over at DP and at duramaxdiesels. He knows more about GM's wiring than most of there engineers do. I know in the trucks it is a plug and play swap where you simply swap everything from the underhood fuse panel and connectors and then run 2 more wires to the OBD2 data port for the can bus. You also have to remember that in 06 the LLY was different from earlier engines, and the 06.5 LLY+ was built pretty much just for the last of the 4500+ trucks. Look at the connections at the underhood fuse box and see if they are the same on both trucks, I know on the 2500/3500 trucks they are.

[Mark Rinker]

My understanding is that by early '06, the 'LLY' was actually an 'LBZ' in all physical (hardpart) aspects, but programming and electronics were still in flux.
Maybe JK can chime in here on programming/electronics issues?

Having owned a 2004 C4500 - I know firsthand that knowledge of these beasts is scarce. We do have a GM medium duty tech on the board, maybe he'll weigh in on some of the issues.

Good luck, keep us posted!