90's Suburban Duramax Conversion

[More Power]

Member Gordon Marks has been hip deep into converting his late 90's 2WD Suburban to Duramax/Allison these past few months. He's getting real close to finishing it, and has already run the engine. We thought you might like to see a couple photos.

http://www.thedieselpageforums.com/photopost/data/500/gordonmarks02.jpg

http://www.thedieselpageforums.com/photopost/data/500/gordonmarks01.jpg

[Shikaroka]

That's interesting!
I'd like to see more about that!

[john8662]

Very cool, now I have someone to shoot questions back and forward to this winter on mine.

Looks like on the blinker signals to clear the intercooler in this install cutting the back side of the lenses and only using one bulb will work, because both bulbs are wired the same.

J

[j_k_auto]

Any updates on this?

[hogmotors]

No updates other than I'm in the middle of the A/C season in FL-fortunately a HOT summer FINALLY!
It does run & drive, I'm in the laborous(?) process of IDing all of the 99 inside harness connectors then "breeding" them to the correct wire in the 01 harness--so when the a/c fuse blows(01 panel)it's actually the a/c that blew it!, etc., etc.
Oh, we didn't mention.....I had a donor truck-01 K2500HD; I'm using all of the harnesses.....mine is a 99 L65 C2500 Sub.
No, there are NO clearence issues...actually, it is about as tight as the 6.5L was.
I'm not a big forum user(cause between this & the 409 stuff I wouldn't get anything done on the truck if I was), so if you have ?'s, post & I'll try to be better about reading. If you're in a hurry, email me @ gordon@marksair.com.
This is NOT a conversion for the "lighthearted"!
G

[hogmotors]

Oh, John;
You are correct about the IC/park/ts.....if you'd like some pics of what I did, email me.
Gordon

[GordonMarks]

I've been driving the Sub for about 3 weeks now. So far, So good. There ARE a very few minor issues; some related to the conversion, some just to the fact that the enging had not run much for about 3 years.

[skittle]

We're in the process of converting a 1999 true half ton suburban gas to 6.5L diesel. So when we go to the parts book, we say we have a '99 1500 4wd Suburban with a 6.5L. We know that they may be looking at a rig with 8 bolt wheels, but we should be ok for what we need. To make a long story short, our gas Sub had a wire driven, vacumm valve that appears to either control hot water flow (or simply on/off flow) to the rear heater. When we ask the gm parts guys how the diesel works, they say there is no valve. They also tell us that the rear hvac box does not have a flow control valve. Can you, or anyone help us out as this doesn't make sense to me. Thanks!!

[More Power]

The HVAC won't change once you install a 6.5 - whether or not there is a difference between the gas & diesel versions.

I recommend using a mechanical fuel injection system in your conversion. It'll be a whole lot easier and less problematic. However, you will need a diesel torque converter for the transmission and possibly a separate transmission control module (TCM).

Jim

[skittle]

We bought a '96 3/4 6.5L pickup with relatively low miles that caught a falling tree. Thus, a great donor. So we have most of the diesel goods needed. The only thing better would have been a diesel Suburban donor. As it is, we ended up buying a couple expensive harnesses to avoid the rewire time. As if changing out the under dash and under hood harness wasn't tough enough. I've found that the '96 and '97 ecm is the same, very good news. As for the electronic pump, I've had good luck if you flush the engine fuel system and buy a new pump. I've also had bad luck, repeatedly, when you don't flush. Hmmm, I guess that may have been the difference between warranty and my dime, eh? At any rate, we'll see if the new diesel harness mates up to the electric over vacumm valve. I'm still uncertain why goodwrench can't see that in the parts book? Is the rear heater a full flow system like the front? If so, do you suppose the gas rig has a shutoff for warmup or emissions reasons? Perhaps one item to note, the rig we are putting together will actually be a heavy half ton six bolt wheel. But the engine and wire harness set up would be like the legendary 1/2 ton Subs with the 8-bolt wheels, which did not have egr. In summary, I'm even more curious about the rear heater flow thing. Thanks!!

[Mitchflatz]

any updates on this? is it finished yet? i'm extremely interested in how difficult the swap was, or what the hardest part was.

[4x4toys]

Updates?:)

[GordonMarks]

Sorry that I haven't been on lately. The Sub has about 12K on the conversion now including 1 trip to Auburn-about 1K roundtrip.
No problems other than my stupidity. It pulls my 10K race car trailer great!!(26" PACE).
Feel free to call me with any questions 800-521-9854x0 & ask for me-If I'm not there, tell them what you want-I'll call you back when I get in. Otherwise; gordon@marksair.com

[GordonMarks]

More:
If you attempt this, you need a GM(HELM) manual for the wiring at least(there are 6 books for the 01) AND Jim's book. The Conversion book has the mounts and a wealth of other info. I had a donor truck, I can't imagine trying this without one like Jim did!
I think the IC clearence is even tighter(is that a word?....motighter?)in the later ones. I cheated, I had been looking at using a full face IC on my 6.5, so I had a bit of a headstart.

[bhastings]

I have a '96 suburban, and just acquired a LML with the allison, transfer case (mine has been beefed up for off-road), controllers, etc. to do this swap. I ran across this thread while researching whether it was feasible, or even possible.

If the original poster is still watching this thread, I'd love a "things I wish I knew when I started" list when you get a chance.

It seems from what you posted that you mated the existing instruments and wiring to the new harnesses. I was thinking I'd just take my dash wiring out and install an instrument cluster and wiring from a duramax truck. Is that naive on my part?

[More Power]

I have a '96 suburban, and just acquired a LML with the allison, transfer case (mine has been beefed up for off-road), controllers, etc. to do this swap. I ran across this thread while researching whether it was feasible, or even possible.

If the original poster is still watching this thread, I'd love a "things I wish I knew when I started" list when you get a chance.

It seems from what you posted that you mated the existing instruments and wiring to the new harnesses. I was thinking I'd just take my dash wiring out and install an instrument cluster and wiring from a duramax truck. Is that naive on my part?

"Things I wish I knew when I started"... My truck was the first 90s era body style converted by anyone in the country - other than maybe at GM. There were many-many questions in the beginning - like "is it even possible?". Now, there is an information resource and the knowledge that it is indeed possible.

I procrastinated for about 18 months in the beginning because I couldn't decide how to proceed with the electrical systems. The mechanicals were easy by comparison.Took grit to strip the electrical systems out of a nice truck - cuz there's no going back. My breakthrough came when I committed to stripping the existing electrical systems and replacing them with systems sourced for my model year engine/trans. Then, it became much easier. Jim

[bhastings]

My breakthrough came when I committed to stripping the existing electrical systems and replacing them with systems sourced for my model year engine/trans. Then, it became much easier. Jim I appreciate the tip. I bought a book that I found online that covers doing the conversion, and I've got the shop manuals coming for both my truck and the '11 silverado that the engine came from. Hopefully that's enough to get me started.