CAT 3126 Swap to Gas

ScottSTL · Jan 4, 2012

Hello, i'm new to this forum and currently have a 2000 GMC box truck with a CAT 3126. The truck is in the shop right now with a scored cylinder, i'm thinking of replacing it with a 454 Chevy just to get it moving again. The shop wants $15,000 for a rebuild on the 3126, i think i'll pass.

Has anyone done a swap like this before? I want to run my Allison if possible but not sure if it could be bolted up to the big block.

Also I plan on parting out the entire engine on ebay, so if anyone needs parts for a 3126, let me know!

guido4475 · Jan 4, 2012

Better have alot of gas money!!! lol..

ScottSTL · Jan 4, 2012

guido4475 said:
Better have alot of gas money!!! lol..

LOL, yeah i was only getting 8.5mpg with the 3126. I figure a solid 5 with the gas motor. Gas is cheaper than diesel though right??? lol

guido4475 · Jan 4, 2012

Is buying another truck out of the question?It would be alot easier, less time consuming, figuring the loss of income while doing the swap, ordering parts, etc.

zorry · Jan 4, 2012

If you don't have the big block why not buy engine-trans together. If you find your old trans is a match you've got a good spare. Or you can sell it.

ScottSTL · Jan 4, 2012

guido4475 said:
Is buying another truck out of the question?It would be alot easier, less time consuming, figuring the loss of income while doing the swap, ordering parts, etc.

I'll probably be putting the truck up for sale if i do the swap. Or i'm considering selling the rolling chassis complete or parting the truck out as well.

zorry · Jan 4, 2012

Or look for a wrecked GMC with 3126. Probably a fast and easy swap.

ScottSTL · Jan 4, 2012

zorry said:
If you don't have the big block why not buy engine-trans together. If you find your old trans is a match you've got a good spare. Or you can sell it.

Just for the simple fact that big block's are cheap, the parts are cheap, and i can fix those easily instead of paying a shop as with the diesel. Most likely the truck will be up for sale once the swap is done.

ScottSTL · Jan 4, 2012

zorry said:
Or look for a wrecked GMC with 3126. Probably a fast and easy swap.

Yeah i have thought of that but the ease of a gas motor excites me. lol

greg334 · Jan 4, 2012

Seeing it is a 2000, the best suggestion is to get A shop manual for it and see what is different. Chances are the cat ECM does more that any gas engine would.

ScottSTL · Jan 4, 2012

greg334 said:
Seeing it is a 2000, the best suggestion is to get A shop manual for it and see what is different. Chances are the cat ECM does more that any gas engine would.

Could you explain this a bit more please?

I'm open to any suggestions...

greg334 · Jan 4, 2012

I don't know what info your looking for. I mean that it all sounds easy to do but it could be a nightmare and long trail to walk.

The suggestion is to start with what you have, figure out what does what and go from there.

Give you an idea, the fl70 I have runs the insturment panel though the ECM and is "programed" for my engine.

zorry · Jan 4, 2012

I meant buy a gas engine hooked to a trans. You'll know it'll work. Then figure out what to do with present trans.

ScottSTL · Jan 4, 2012

greg334 said:
I don't know what info your looking for. I mean that it all sounds easy to do but it could be a nightmare and long trail to walk.

The suggestion is to start with what you have, figure out what does what and go from there.

Give you an idea, the fl70 I have runs the insturment panel though the ECM and is "programed" for my engine.

Okay gotcha, yeah i didn't know about the instrument panel running off the ecm. That could definitely be a nightmare...

My goal was to get it running for cheap simply because the truck isn't worth that much and dropping a ton of money on a rebuild isn't cost effective for me.

ScottSTL · Jan 4, 2012

zorry said:
I meant buy a gas engine hooked to a trans. You'll know it'll work. Then figure out what to do with present trans.

Yeah thats a good idea... i wonder how well a 4l80 pick up truck transmission would hold up?

greg334 · Jan 4, 2012

ScottSTL said:
Yeah thats a good idea... i wonder how well a 4l80 pick up truck transmission would hold up?

I wouldn't consider anything less than a Allison 1000. The 4l80 is too light for that truck seeing it had a 3126

Ever consider a cummins isb?

cableguymn · Jan 4, 2012

ScottSTL said:
Hello, i'm new to this forum and currently have a 2000 GMC box truck with a CAT 3126. The truck is in the shop right now with a scored cylinder, i'm thinking of replacing it with a 454 Chevy just to get it moving again. The shop wants $15,000 for a rebuild on the 3126, i think i'll pass.

Has anyone done a swap like this before? I want to run my Allison if possible but not sure if it could be bolted up to the big block.

Also I plan on parting out the entire engine on ebay, so if anyone needs parts for a 3126, let me know!

several posts down from your parts post on CL.

2000 Freightliner FL70/FL80 for parts

Buy the engine out of that one.

If I was looking for a truck, the last thing I would want is a gas engine in it. You would be doing more damage to the value of the truck by switching to gas than if you just left the engine in it.

Ever thought of checking with a local diesel school? They do great work if your not in a hurry. Since your going to dump it after repairs I don't think it would be a huge deal to wait on it. You'll pay for parts, but the labor is free.

http://www.rockanddirt.com/search?l0=attachments&l1=CAT&l2=3126&l3=engines

Some running usable ones for 3500.. Probably be 500 to get it to you. As long as it runs well and your planing to sell. I'd dump one of those in. 4000 is likely what a 454 and conversion is going to cost you anyways.

You'll also have to check in to EPA laws. Dumping a gas engine in to a 2000 truck means all sorts of smog changes to get it up to snuff. The fines for selling it with out them (if someone complains) is nothing compared to the cost of a rebuild.

ScottSTL · Jan 4, 2012

cableguymn said:
several posts down from your parts post on CL.

2000 Freightliner FL70/FL80 for parts

Buy the engine out of that one.

If I was looking for a truck, the last thing I would want is a gas engine in it. You would be doing more damage to the value of the truck by switching to gas than if you just left the engine in it.

Ever thought of checking with a local diesel school? They do great work if your not in a hurry. Since your going to dump it after repairs I don't think it would be a huge deal to wait on it. You'll pay for parts, but the labor is free.

http://www.rockanddirt.com/search?l0=attachments&l1=CAT&l2=3126&l3=engines

Some running usable ones for 3500.. Probably be 500 to get it to you. As long as it runs well and your planing to sell. I'd dump one of those in. 4000 is likely what a 454 and conversion is going to cost you anyways.

You'll also have to check in to EPA laws. Dumping a gas engine in to a 2000 truck means all sorts of smog changes to get it up to snuff. The fines for selling it with out them (if someone complains) is nothing compared to the cost of a rebuild.

Yeah i've sent that guy a few a emails, i need to go and take a look at the truck. Considering what my truck would be worth once its running has me concerned on even trying to attempt any kind of replacement engine project.

cableguymn · Jan 4, 2012

ScottSTL said:
Yeah i've sent that guy a few a emails, i need to go and take a look at the truck. Considering what my truck would be worth once its running has me concerned on even trying to attempt any kind of replacement engine project.

Sell the box/sleeper off it, sell the hood off it and junk the rest.

Or, buy a new truck with out a box/sleeper and put yours on it.