Hey guys, I don't come to the 7.3L forum often, but Stewart suggested that this could have been of some use for you guys.

As a little background, I recently installed a 6.0L cooler on my Excursion to keep the transmission cool when I pull my enclosed trailer out to Connecticut next month. Fully loaded it's likely going to be nearly 14,000 lbs, and so several people recommended the 6.0L cooler. The problem is that I would never get up to temp after this; last week when towing my 3,500 mile boat to the shop 40 miles from here it never got over 123°F. This is a problem for driving off moisture as well as efficiency, as the transmission really was intended to operate much warmer than this. So after some research and suggestions from folks here on FTE I finaly had a plan. Here's what it is:

Derale 13011 Fluid Control Thermostat Kit : Amazon.com : Automotive

Today I finally got the chance to install the Derale 13011 transmission thermostat kit. I paid around $65 for the kit from Amazon.com, and it comes with the 3/8" barbed fittings that are necessary for the install. Here's what came in the box:



Pretty simple thermostat setup not unlike the engine coolant thermostat:



The first step was to wrap the threads of the fittings in teflon tape to provide a good seal and install them in the thermostat housing:



And then splice them into the cooler lines. Note that the metal line for the outgoing fluid to the cooler is the one that ends closest to the radiator. The return line terminates closer to the engine. I chose the bracket on the passenger side of the frame behind the bumper for the mounting location, and I used a huge zip tie to secure it there:





I started it up, checked for leaks, and after being satisfied of this I started driving to see how well it worked. Over the course of fifteen minutes, in 39° weather, I went from 47° to 174° F. Once it hit this point the thermostat opened up and it fluctuated between 173° and 175°. VERY satisfied at this point. I plan on getting some better hose clamps as I'm not happy with how these are gripping and I also have to find a way to test the flow through the cooler because I'm a bit nervous about how much I had to curve the lines to get them to work.

I won't be driving it again until next week, and I'll be hooking in my AE and logging the transmission temps on my 43-mile drive to work. I will post the graph at that time.

 

Good information. I've always wondered if the oil could be kept too cool. Don't know why that would be a problem but just wondered.

One problem I see with the installation is if you are just clamping hose to metal lines you may be in for some trouble. I did that on a transmission conversion I did years ago and would blow the hoses off the metal lines even though they were only cooler lines. I tried grooving the metal lines but that didn't help. You should put a compression or flair fitting on them to be safe. Just my observation. Otherwise a nice clean install.

 

EDIT: I looked at the specs and the thermostat control is fixed and preset... not adjustable.

I also saw that the max flow allowed to your cooler is "95%"... so it will be interesting to see your experience in summer heat with heavy loads. If you can't keep your temps down at that point, you could always switch to the larger 1/2" unit which would effectively allow a larger percentage of your true flow through your cooler.

 

Thanks! I don't think I'm going to have a problem though, as the fittings going into the thermostat are barbed fittings, as are the ends of the factory metal lines. Not sure how this was done on other trucks but the factory rubber lines were held on the barbed metal hoses with regular hose clamps. I'll be keeping an eye out for problems though, and I would guess that this would be more of a problem in cold weather with cold, viscous fluid.

Someone in another forum suggested double clamping them as well, which I certainly plan to do. Need to find some better clamps though, as I'm really not happy with these ones.

That's a good point, and unfortunately I don't know of a good way to flow test this thing. I'd have to find a way to get my transmission HOT, shut it off, pop off the return line from the cooler before the T-stat, and make an assumption that the T-stat is all the way open. I'm also concerned with the curvature of the lines to the cooler, but I couldn't find a better place to mount it. So we'll see how it goes. I'll be datalogging my temps next week on an unloaded commute to work, and then again when I hook up my loaded trailer to it.

 

The specs on the Derale site say it will flow 20 GPM. If Mark K chimes in, he will know if that is adequate from a flow standpoint, but I believe it is well enough over the tranny pump's flow rate to be fine.

 

The cooler flow on a 4R100 is about one gallon per minute at cooling line pressure.

Just saying it will flow 20 GPM is meaningless. At what pressure? Flowing 20 GPM at 1 PSI is a lot different than flowing 20 GPM at 30 PSI.

 

OK... glad you joined us, Mark.

You're right about the pressure/flow relationship. In looking through my Cameron Hydraulic Handbook at the flow through 3/8" tubing, the velocity for 1 gpm is only 1.7 fps which is almost 1/3 the typical minimum velocity we use for "good engineering design" in industrial pumping systems.

I know that there are things which can be considered such as length of run through the 3/8" rubber tubing, differential pressure across the cooler itself, etc., but given the relatively short runs of tubing, I would initially conclude that the 3/8" tubing with the 3/8" thermostat would allow for acceptable flow rates with minimal pressure drop.

What are your thoughts?

 

My thoughts are that it will flow plenty of fluid with minimal restriction. Keep in mind that not only have I not tested one of these, I've never even seen one in person.

 

I'm in the same boat. Thanks Mark.

 

I have had one in for quite a few months...heavy hauling throughout the summer in temps above 100 degrees. The temperature of my fluid got to 200 once and I was really pulling some heavy stuff over Donner (41 miles of upgrade, 7% grade). I have also "walked" the truck from highway 95 into my mining claims at about 3 mph for two hours...never got hotter than 200 degrees. I think the flow from the tranny is so great that even a 5% restriction, with adequate heat exchangers, still cools the tranny just fine.

 

Is there a proper cooler/flow rate for our 4R100? I know the stock additional cooler on our 1999-2004 trucks is mounted low(air dam on front bumper)
But the 6.0 cooler for the 5R110 is bigger and flows better)
Is there a need for a cooler/or additional filter setup?

 

The proper flow rate for a 4R100 is one gallon per minute at idle.

If you tow heavy you probably need to replace the stock cooler with a cooler from a 6.0L truck. The stock cooler is not adequate.

 

I was just thinking about this Mark. How much does the flow vary during normal operation? Does it vary with engine RPM or some other factor? Also what is the maximum pressure that the cooling circuit would see?

 

It will vary some with RPM. The cooler circuit comes off the torque converter. The feed to the torque converter is limited to 120 PSI. The cooler circuit in a 4R100 won't see above about 30 PSI. That's an estimation, I don't know the actual limit.

 

I have similar concerns about running too cold in winter temps with the 6.0 cooler, so I put together a manual by-pass valve set up (not installed yet - or cooler). I used two 1/4 pipe tees with a ball valve between them with 3/8 barb fittings on the trans side and 1/2 on the cooler side with a ball valve on the return side to the trans before the tee so that I can control and/or completely bypass the 6.0 cooler if necessary. I have the in-radiator cooler which Mark felt should be enough when temps are in the teens/twenties but I will see soon enough.