Duramax Diesel Conversions

[DmaxMaverick]

The brake fluid level indicator sensor is a normally open circuit, closed when the fluid level is sufficient. You should be able to shunt the connector to get the lamp to go out. If you do this and the lamp stays on, then you have another sensor or switch in the system that's not happy, or missing, or the brake fluid level harness is not wired correctly into the system. The EBCM (Electronic Brake Control Module) receives the input from the brake fluid level switch, and controls the IP lamp. If you pacify all the switches/sensors, and still have the lamp on, I'd suspect an issue with the EBCM, or a weak/missing ground in the circuit. If you haven't installed the late model EBCM, that could very well be the problem, with the BCM missing the input, or the input is not correct from the park brake switch (which is monitored by the BCM)

[HH]

When beginning a project as complex as a Duramax conversion, it's helpful as you work through the project to use checklists, and then concentrate on one or just a few steps at a time. A person can become bogged-down and discouraged when contemplating the entirety of the project. Again, just concentrating on a few steps at a time helps to keep you focused, and allows you to see and measure progress in real terms.

When our project was in the planning stages, and while actually working through the conversion, I created many lists that I used to help keep me focused. Here's one of those lists (yes, I kept them all).

When taken as bite-size chunks, the project becomes doable for most people. A list helps keep you focused....

Jim

This is excellent advice. I have done this and it makes me more focused and also helps me plan ahead so I have the parts I need when I have the time to do the work.

[GordonMarks]

I should have mentioned that during my conversion Jim's book was priceless!! I had no one else to discuss the conversion with since not too many had tried it at that time. I used his mount patterns with some minor mods(which I forwarded to JIM) for the 2WD since I didn't have the transfer case to contend with like he and Ferman did. Mine could sit lower in the frame.
As I mentioned, I'd be glad to talk to anyone about the conversion-my contact info is in the other emails.

[More Power]

I've added several links to Duramax Diesel Power Project page, that discuss the rear disc brake conversion and include more details about the truck's interior. Also, we've begun offering professionally produced motor mounts that greatly simplify a conversion. See the mounts here. Jim

[More Power]

A new article is now available online about a 1998 Chevy K1500 LBZ...

https://www.thedieselpage.com/duramax/1998LBZ.htm

[arveetek]

A new article is now available online about a 1998 Chevy K1500 LBZ...

https://www.thedieselpage.com/duramax/1998LBZ.htm

Very nice!!

Casey

[More Power]

Very nice!!

Casey

Blake is really nice guy. I hope we do get together at some point. I heard from him a few days ago, and he said he's still "living the dream".
Jim

[TheCanadianGoose]

Hello everyone
I'm currently building a truck it's a 1998 Chevrolet K3500 crew cab dually, it has the 6.5/4l80e combo which is ready to pull. I'm going with a 03 LB7 and allison trans. I currently have the harness getting reworked by Ken Wolkens for a stand alone and have the ECM and TCM already reflashed. Now the questions I have is what is all needed to integrate the LB7 to work with the GMT400 platform? I was told the starter relay will not work along with the gauges, what is all reguired to get the HVAC system working with the 98 hvac and the lb7? and what other problems will I have to figure out? thanks

[More Power]

I received this email this morning, asking about an '80s square body conversion. Thought the discussion might be of value here.

On 2021-04-15:
> I am considering doing a Duramax/Allison swap in my 1984 chev c70
> rollback it currently has a 427 5 speed,
>
> In has a cable driven speedometer I wondering what you have done to
> correct that ?
>
> Also does the Allison have the required hardware internally to drive a
> PTO , I know it has a cover plate but what about the internal gear
> required to drive the PTO
>
> If I do proceed with this project I will be purchasing you guide. Do
> you need to buy a wiring harness to make the conversion or does the
> guide show you how to modify the existing harness.
>
> Thanks In Advance
>
> Larry
>
>

Hi Larry,

I recommend you modify the dash of your 1984 truck to accept the new instrument panel. This will solve the speedometer problem and you'll gain a lot of functionality with the new powertrain. I also recommend you install the steering column that matches your engine package. This'll make it easier to shift the Allison, and it'll add a lot of functionality as well.

I know the early Allisons were setup to run a Power Take-Off, but I know the PTO was dropped a few years into production... before re-adding PTO in more recent models. So, to answer you, I don't know. I guess it sort of depends on model year, but I don't have a model year breakdown for the PTO.

For wiring harnesses, I recommend using the OE harness that matches/came with your engine package. New, these factory harnesses are about $600/ea (one for the engine and one for the Allison). One of the more expensive options is to acquire an aftermarket stripped-down harness that was designed for boats/RVs/basic conversions, but they require a specially programmed ECM/TCM and you'll lose most/all of the luxury features that came with GM's 2500/3500 trucks. Contact ppepower.com or bankspower.com for more info about their harnesses and ECM/TCM. Just remember that using an OE harness doesn't force you to use the extra features - you can pick and choose. The Conversion Guide we offer shows you how to install the OE harnesses, which is the least expensive option - no cost if it came with your engine/trans.

In the meantime, I'd suggest you spend some time with the following article that shows a 1987 Chevy C30 conversion...

https://www.thedieselpage.com/featur...Conversion.htm

Good luck,

Jim

[More Power]

On 2021-04-27, mj m wrote:
Good morning! I have a few questions about the Duramax Conversion Guide....

I wanted to know if there were instructions for how to modify dash components in a truck prior to 1995... I know that you did this in your 1989 truck but was curious if the instructions are included in the guide.... Second, does the Guide specify which intercooler to use.... and the last question, are the engine mounts still available for purchase?

Hello,

Yes to all questions.

I recommend modifying your original dash to accept the instrument panel from the truck matching your engine package. I did not go that route, but many others have. It'll require fabricating a "surround" that blends your original dash into the new instrument panel. Generally, a custom automotive audio installation shop would have someone with the skills necessary to do a great job - sorta like fitting custom speakers into a vehicle that didn't have them.

That said, the Conversion Guide does show how I installed a complete new dash into my 1989 Chevy. It's a big job... If you go that route, I'd install the new truck's HVAC package and venting system along with the cross-cab aluminum underdash support. That way you'll be able to use the new truck's HVAC (heating, venting, air conditioning) dash control panel and the system's climate control... and it'll make for an easier installation. I also recommend using the new truck's steering column - for Allison shift function and electronics - plug n play. You'll just need to relocate the firewall mount bracket on the new steering column.

I used a Dodge diesel pickup intercooler, but others have used a Duramax intercooler... I used a Dodge part because that's what I had access to in 2003. The Guide shows how to modify the intercooler and how to install it. An intercooler is essential for a performance truck or one that will be used to tow heavy. For a light-duty easy driven truck, the intercooler is more optional. I know of some who didn't install an intercooler and their truck did just fine.

The motor mounts are still available.

Thanks,
Jim

[More Power]

Recently, I've received a couple of requests for more information concerning a Duramax/Allison conversion in the 1990s 2 Wheel Drive (GMT400) body style trucks, asking whether the motor/engine mounts we offer would work. The answer is YES, but the transmission mount crossmember would need to be modified. Member Gordon Marks kindly sent me a couple images of his modified transmission crossmember, which explain how he accomplished his installation. Thanks Gordon!

Note: The factory 4WD GMT-400 (1990s) transmission crossmember works perfectly without modification in 4WD trucks. It appears the 2wd TRUCKS/SUVs have a somewhat different frame rail dimension when compared to the 4WD models. Mock-up the installation before committing to welding on the added material. You may find you need to adjust the height up/down a little to get ~ 3/4" clearance between the rear of the transmission and the transmission tunnel.

You can see from these photos that Gordon flipped the modified 2WD crossmember upside down and mounted it below the frame rails. Be sure to use lock-washers and thread locking compound just to be sure. Jim

[More Power]

I received this message and photo from Patrick yesterday. You can expect to see his truck on the road somewhere in Massachusetts before long!

Jim

From: PatrickS
Subject: The Diesel Page - Duramax Conversion Mounts
Date: Mon, 24 May 2021
To: The Diesel Page
Jim,

The mounts arrived today and I was impressed with the quality of the parts. After work I bolted them up and, while an involved process, I got the drivetrain in. The mounts were worth every penny.

Patrick

2000 K2500, CrewCab Shortbox

[DayRadebaugh]

I have a low mileage '99 Suburban with a 6.5. I saw the discussion of the conversion to Duramax, but it said it was intended for only the '88-'98 models. Am I correct in thinking that the difference would be in the dash-instrument cluster only?

Thanks

[DmaxMaverick]

It depends on the body style you have, GMT-400 or GMT-800. 1999 was a transition year, and I don't recall how the Suburbans were released, if they were a half-year release, or if there was a difference between the weight classes. 2001 was the first model year for the Duramax. GM has always found a way to defy any direction of logic during these times. A GMT-800 (1999+) would be the simplest, with very little accommodations to consider.

[DayRadebaugh]

It depends on the body style you have, GMT-400 or GMT-800. 1999 was a transition year, and I don't recall how the Suburbans were released, if they were a half-year release, or if there was a difference between the weight classes. 2001 was the first model year for the Duramax. GM has always found a way to defy any direction of logic during these times. A GMT-800 (1999+) would be the simplest, with very little accommodations to consider.

Thank you. Would you happen to know how I can tell the difference? From what little reading I've done, I'm guessing mine is a GMT 410.

[DmaxMaverick]

I suppose I was asking the question. Which do you have? I simply don't recall what GM did during that transition, and I don't know what the equipment and RPO stickers should show to determine it. As sure as the sun rises, when you have it all figured out, an odd duck will show up. If yours looks like previous 1990's models, then it's a 400. If it looks like more modern models up to 2006, then it's an 800. It's important to the simplicity because a later model will fit the instruments and harnesses you'll need, rather than shoehorning everything. Look at the panoramic picture at the top of this page. Which grill looks like yours? The trucks on the far left and right are GMT-800 trucks, with different models mixed in between. Lil' Red is a GMT-400.

[More Power]

Hello everyone
I'm currently building a truck it's a 1998 Chevrolet K3500 crew cab dually, it has the 6.5/4l80e combo which is ready to pull. I'm going with a 03 LB7 and allison trans. I currently have the harness getting reworked by Ken Wolkens for a stand alone and have the ECM and TCM already reflashed. Now the questions I have is what is all needed to integrate the LB7 to work with the GMT400 platform? I was told the starter relay will not work along with the gauges, what is all reguired to get the HVAC system working with the 98 hvac and the lb7? and what other problems will I have to figure out? thanks

Many questions....

First, there's no need to have the Duramax underhood/in-cab harnesses reworked. With the exception of splicing in the HVAC controller/package wiring into the Duramax in-cab harness, the rest of the original in-cab/underhood electrical will be stripped out and replaced with the Duramax harnesses, fuse panels and electrical centers. This actually makes it all a lot easier. Trying to jury-rig an old/new composite electrical system adds so much complication to the conversion that it discourages most who attempt it.

The ideal is to create an electrical system that looks and functions like the factory Duramax system. The truck will be worth more at the end and it'll be easier to troubleshoot if a problem does appear.

Here's a story about a 1998 Chevy LBZ conversion that used our motor mounts and Conversion Guide

This Thread has answers for some of your questions.

Our Duramax Conversion Guide has answers for most questions.

[More Power]

I received this message and photo from Patrick yesterday. You can expect to see his truck on the road somewhere in Massachusetts before long!

Jim

From: PatrickS
Subject: The Diesel Page - Duramax Conversion Mounts
Date: Mon, 24 May 2021
To: The Diesel Page
Jim,

The mounts arrived today and I was impressed with the quality of the parts. After work I bolted them up and, while an involved process, I got the drivetrain in. The mounts were worth every penny.

Patrick

2000 K2500, CrewCab Shortbox

This above message was posted in may of 2021... just about 2 years ago. I received an update from Patrick a few days ago, along with an order for another set of our conversion mounts. I like his truck's new hood! Here's what Patrick said recently:

These mounts are actually the second set I’ve purchased.

A couple years ago I bought a set to put an LB7 in a 2000 K2500. I chose not to body lift it and instead made a HD hood. Attached is a photo of that truck.

I’ll keep you updated on this trucks swap.