Ultimate Wrangler Cooling
Project Money Pit's cooling system goes to the next level Short Cuts
by: Ron Hollatz - 6/2001

Jim Hoeft from 4x4 Unlimited installs the transmission cooler on the Griffin radiator.
finished from front
Straps were used to mount the transmission cooler for added strength.
finished from front
No need for a fan shroud here.
The new fan and radiator installed in Project Money Pit.
top view installed
The radiator was mounted slightly forward to allow clearance for the water pump pully.
outside view
Should have plenty of air flow now.

Many of you are familiar with the cooling upgrades I've made to Project Money Pit. Last summer, while installing a 700R4 transmission, I added a B&M transmission cooler, FlowKooler water pump, and high flow thermostat housing from Turbo City. While each of these upgrades helped get the temperature down for rock crawling in normal weather, the temperature still went up into the danger zone when the weather got hot. It was time for some drastic measures.

Where to go from here

I had already taken my radiator to a local shop to be pressure tested and cleaned out, so I knew a stock replacement radiator wasn't the solution. That left me with a choice of a stock-type radiator with more cores, or a custom bolt-in aluminum radiator. Aluminum radiators have several advantages over stock radiators. Traditional radiators use several rows of small tubes surrounded by fins. These small tubes allow greater contact area between the tubes and fins. The drawback is that the small tubes are easily clogged. As coolant circulates through the tubes, corrosion occurs making the passages smaller and smaller. In contrast, aluminum radiators are constructed with larger tubes with less restriction. This allows for greater fin contact area with fewer tubes. Aluminum radiators are also lighter, but the stock radiator in my YJ was so small that there really wasn't any weight benefit.

Several companies offer bolt-in aluminum radiators for Jeep vehicles. Unfortunately, I had a severe case of sticker shock when I started pricing them. Many run in the $500 range. I'm sure they bolt right in and work great, but I had a hard time justifying the cost. I had also been using a dual electric fan setup instead of the factory installed mechanical fan. I was concerned that the fan would hit the water pump pulley with the thicker aluminum radiator. So I was right back where I started with no solution in sight.

While I was trying to decide what to do about the radiator, Project Money Pit was sitting in the back corner of 4x4 Unlimited waiting for the new axles to be completed. I happened to be at the shop one day when UPS arrived, and I noticed a radiator box. It turned out to be a universal aluminum radiator that was going to be installed into a CJ5 used for mud racing. I took some measurements and was surprised to find that it was close to the same width as my stock radiator. However, universal radiators don't come with any mounting brackets installed. I sat down with Jim Hoeft, the owner of 4x4 Unlimited, and he said he didn't see any problem with adding some mounting brackets to allow a universal aluminum radiator to fit in my YJ.

Choosing the right parts

Now I had to find the right radiator to use in my YJ. Most universal radiators come in either a Chevy or Ford configuration, not Jeep. The difference between the Chevy and Ford is the location of the outlets on the radiator. Ford radiators have the upper outlet on the right, and the lower outlet on the left. Chevy uses the opposite of that configuration with the upper outlet on the left, and the lower outlet on the right. Luckily the Jeep engineers used the same setup as Ford. After checking around I decided on a Griffin 22" x 19" universal Ford style radiator, part number 126182. The Griffin radiator is a little shorter and wider than the YJ's stock radiator. Griffin uses 2 rows of 1" diameter tubing for maximum tube-to-fin contact. Their radiators are also heli-arc welded for added strength. After welding, the radiators are furnace brazed which anneals the aluminum, making it flexible to reduce punctures. The last step in their process is to reinforce the radiator with high temperature epoxy to resist failure brought on by vibration. If their radiators could stand up to the rigors of NASCAR racing, they should be able to stand up to the abuse on a Jeep.

While discussing the project with Jim, he mentioned an electric fan they had been using on other vehicles with really good results. The fan is a Ford part, RF-39, used in late model Crown Victoria police cars. Since police cars spend much of their time idling, they needed extra cooling. He wasn't sure of the years it was used, since his shop orders the part from Ford. A Toyota Land Cruiser in the shop already had one installed for me to inspect. I could hold my hand a couple of feet way from the grill, and feel the air being sucked in. My dual fan setup was no match for this. The Ford fan comes with a huge shroud, which needed to be removed to fit in my YJ. However, the fan itself ended up being the same diameter as the new Griffin radiator.

Making it fit

Now it was time to make the radiator and fan fit in the engine compartment of my YJ. After the old radiator was removed, it was time for some measurements. The combination of the thicker radiator and fan would require the radiator to be mounted slightly forward of the stock location. This required a little trimming of the grill with a cut-off wheel. This might not have been necessary, but my transmission cooler mounts on the front of the radiator. Jim welded a piece of angle aluminum to each side of the radiator. He also added mounts for the transmission cooler, the electric fan, and the power steering reservoir. The power steering reservoir is usually mounted to the radiator brackets on YJs. The welding from Jim was perfect as usual. Everything fit like it came that way from the factory. The stock hose was used on the top outlet, while a flex hose was used on the bottom outlet. We also took the time to sink my winch between the frame rails with one of 4x4 Unlimited's front bumpers. Now I have nothing blocking the air flow into the radiator.

Final Thoughts

I'm really happy with the way the project turned out. So far the temperature is staying between 180 and 200 degrees, which is a bit cooler than I would like. The 4.0 litre runs best at around 200 degrees, so I'm going to put in a 195 degree thermostat and add a thermostat to the fan circuit to keep it off unless needed. I would also like to add some type of venting to my hood because there is a noticeable difference in the fan's draw when the hood is closed. I'm thinking there is too much air pressure under the hood so the fan can't pull as much air as it likes. I also wish I would have remembered to have Jim put a petcock in the radiator. It was one of those things that kept popping up in my mind, but never when I could do something about it. It wasn't until we were messing around with the lower hose that I realized there was no way to drain the radiator. All of these things are minor and the improved performance more than makes up for them. The best part is the whole project cost about the same as one of the custom bolt-in aluminum radiators. The fan was the most expensive part, so make sure you are dealing with someone who gets a good discount from the Ford parts department. Jim mentioned he would be happy to build more of the radiator/fan combos if anyone is interested. I can't wait to see how Project Money Pit performs in hot summer weather.

Contacts: Related Links:
  • 4X4 Unlimited
    Dept. ORN
    10025 40th Ave. NE.
    , MN 55932 USA
    Phone 507-285-1231
  • Griffin Radiator
    Dept ORN
    100 Hurricane Road
    Piedmont, SC 29673 U.S.A.
    Phone (864)845-5000
    Fax (864)845-5001

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