2001-2005 Auxiliary radiator kit specific information

1) Q. Why does my truck LLY overheat?

A. This is a complicated question, there are many factors that contribute to the overheating issue. The easiest way to find the major factors is so look at how G.M. fixed it in the later model (LBZ). Increase cooling capacity and increase airflow over it. It is possible to install the cooling system of a LBZ on an LLY, it has been done with some success but the cost is upwards of $4,000.00 due to the number of parts that must be replaced to accomplish this.

2) Q. Is my Duramax an overheater? 

A. Although the LLY (2004.5-2005) duramax is the most common model year to have cooling issues, there are some earlier models (LB7) and some later models (LBZ) that still get warm. Transversely there are some LLY's that tow at and above their G.V.W. that don't have overheating issues. The best answer would be, if you are experiencing excessive coolant temps and you have made sure everything on your truck is functioning correctly, you likely have an overheater.

3) Q. Will this kit work for my Chevy GMC LB7 LLY LBZ?

A. This kit has been installed on the following models;

LB7, LLY, LBZ, engines. In both Chevy and GMC models. The vast majority have been in the Chevrolet LLY (the truck it was initially designed for). It will require a little more trimming of bumper internals and adjustment for the GMC model.

4) Q. How hard is this system to install and how long does it take to install it?

A. Most installations take about 4 hours and require minimal tools and mechanical know how. The kit comes with detailed instructions as well as a list of required tools for the job.

5) Q. Is this guaranteed to fix my Duramax? 

A. At this point there is no guaranteed fix. One thing that has become obvious over the last 3 years, each of these truck have a personality all their own.  As stated above, there are some that get hot with as little as 7,000lbs behind them and there are some towing above 12,000lbs that have no coolant temp issues at all. Of the 70 systems installed there are a few (3 to be exact) that still get warm. The improvement over stock was drastic but they can still get warm if they push their trucks hard. It was for this reason I have improved and added to the system I initially designed.

6) Q. My Duramax has never overheated but I have not towed with it, is it an overheater?

A. The overheat issue with the LLY is limited to heavy loads on the engine. If you have not towed enough weight to consistently push your truck hard, you will not know if you have an issue.

7) Q. Are there any other know issues that require fixes with my Duramax?

A. With some trucks excessive oil temps have been reported. This has been a case by case issue and like overheating is not present in every truck. If you are pushing your truck hard I suggest installing an oil temp gauge and monitoring it. 

8) Q. If I install this system and my Duramax still gets warm while towing, is there anything else I can do?

A. Yes, I also have a larger aluminum main radiator with a larger transmission cooler that is offered in conjunction with the secondary cooling system. This is available for those extreme cases and offers maximum available cooling.

9) Q. Any other suggested improvements?

A. There are a few I recommend;

Replace the turbo mouthpiece with an aftermarket less restrictive one. 

Upgrade to a Cold Air Intake.

Pump Rub plate in the transfer case.

Pressure vents for the engine compartment.

Stack sealing

After market coolant temp gauge

Oil temp gauge

Aftermarket transmission cooler

10) Q. What kind of warranty and or guarantees does this kit come with?

A. Warranties are limited to manufacturer warranties of the individual parts. Although this system was designed for our trucks, every truck is a little but different thus requiring slightly different install. Proper installation and function is the responsibility of the buyer. This system has been installed on over 70 trucks with no issues and has been on my truck for over 3 years with no issues but the responsibility of guaranteeing proper fit, function and maintenance falls on the buyer. 

11) Q. If I have issues during my install, what kind of assistance is available?

A. I offer tech support in the form of my phone number. I am happy to answer questions free of charge to assist with an install.

12) Q. Is there anywhere that I can pay to have this system installed and how much does it cost?

A. Yes, there is a local shop that has installed a few systems for me. They charge 4 hours labor to do the install. There have also been shops out of stat that have installed this system for similar labor rates. 

Any more questions? Feel free to email me. Engineer837@cox.net

  Here are some generic instructions to give you an idea of what all is entailed in installing one of these kits.   Actual instructions will be specific to your kit and will come with detailed pictures.  As always I offer phone support to you or the shop you have do the work for you.

Required tools;

2 - 3/4" sockets and drivers, 2 - 15 mm sockets, 1 - 7/16" wrench, 1 - 3/4" wrench, 1 - med. crescent wrench, 1 - 8mm socket screwdriver, 1 - 1/4" socket screwdriver, 1 - pair of scissors, drill with 7/16" bit, box cutter. For GMC you will need a Dremmel or cut off wheel for removal of some small metal pieces from the inside your bumper.

Installation instructions:

First uninstall your splash guard.

Next remove the bolts that run vertically through the bumper mount. The bolts/nut assembly will have to be replaced because it is not long enough to support the radiator and the motor mount you will be using. Save these bolts, they will be used later.

Now fit your radiator up in place and mark your holes on the upper brackets (It helps to put the 90's on the ports of the radiator when marking your holes to be drilled. This insures a correct angle for your plumbing later.) Pull the radiator out and drill them. (it helps to drill these holes slightly larger than the bolt that will be going through it). You now need to use 2 of the 7/16" x 2" bolts, 4 of the 7/16" washers and 2 of the 7/16" lock nuts, these bolts will pass through the bracket, motor mount and radiator mount. One challenge you will face here is being able to reach the top of the bolt while the radiator is in place. This can be done by coming down from the top between the grill and radiator. 

Before you bolt your radiator up in place for the last time you need to install your degas fitting and hose. BE SURE TO USE TEFLON TAPE ON THIS FITTING AND TO NOT OVERTIGHTEN IT. NEVER THREAD AN ALUMINUM FITTIN INTO ANOTHER ALUMINUM FITTING WITHOUT TEFLON AS THE THREADS CAN SIEZE.

So with your fitting and degas line installed slide your radiator back up in there for the last time and bolt it in place. Now it's time for the lower bracket. 

Here you will use those two bolts you removed from the bumper bracket. They will be used to attach the bracket to the side of the tow hook support. The ones you remove will not be long enough. For the connection between the lower bracket and the lower tabs of the radiator you will use the remaining 7/16" x 2" bolts, 7/16" washers and 7/16" lock nuts. I have purposely not put hole locations with measurements due to the fact that all of our trucks are a little different and will likely require slightly different holes. For the best results mark and drill them yourself. This should conclude your mounting of the radiator. Now on to plumbing.

Start draining your system. While this takes place you can hook up your degas line. To do this you will have to make an adapter to splice into your current degas line system. The factory hose is ½ (I think) and the one on your radiator is ¼”. This is what I made to make the splice.

This line is very important to purge air out of the system. Do not cap that fitting and skip this step.

The degas line goes from the bottom of your overflow tank to the top of your radiator on the passenger side. I ran my blue line in front of the coolers zip tying it to the holes on the back of the bumper then up to the degas on the pass side. This keeps the hose out of the way of any moving parts.

By now your system should be mostly empty it is time to work on your lower radiator hose. The first thing I did was cut the lower radiator hose in the middle. By the middle I mean roughly centered to the radiator. (watch out because there will be fluid left in the hose when you cut it) 

Once the hose is cut take your 2 - 2” 90’s and slide them in place. Take a look at how you want to plumb it and start trimming. The key here is to plumb it so that none of your hoses have any kinks in them. For me the easiest way to accomplish this was to plumb it in a cris cross fashion rather than go from right port to right port then left to left.

To join the 4 hose ends use the flanged tubes provided by Ron Davis. Now it's time to tighten you hose clamps and fill it with fluid. Be sure to carry 2 gallons of coolant and water, my system continued to purge for a day or so till it was finally full. Overall I think it added a little over a gallon to the system.