This post kinda stemmed from the "how much weight you have hauled" thread

Last summer I installed a tranny temp guage and aTru-Cool 4739 and I think it was rated at 40K pounds....(whatever that means, I assume GVWR)

What I have discovered is that the amount of WEIGHT that I am towing doesn't seem to have very much affect on the temp. of my tranny fluid versus SPEED.

For those of you who don't live in central Texas, its pretty flat here for the most part, not western Kansas flat, but pretty flat. When i pull or haul, which I usually do 10K or so at least twice a week and then depending on what were doing 25-40K sometimes.......when towing heavy loads my truck will rarely go faster than 40-60 mph...the 60 is usually downhill. BUT, the tranny temps stay around 175-190 degrees.

I have noticed this fall, when outside temp was around 50 degrees that when traveling on the interstate for extended periods of time with the cruise set on 80 my tranny temps will get up to 210 going on 220 and I have to slow down for awhile and let'er cool down. (this is 80 mph EMPTY, NOT pulling a trailer)

Again, for those that don't live in Texas 80 mph is normal interstate driving and down on I-10 between SA and Houston I am usually holding up traffic at that speed.

Is something wrong with my tranny? or maybe tranny coolers should be rated for "highway speeds" instead of by GVWR ?

what do you guys think ?
ra

 

When I am towing, mine heats up when I go over 60-65. Below that the temp stays normal. 70 is about top speed. If I set the cruise to 80 it would not matter. If I am towing heavy loads I don't want to go too fast anyway. My trucks weigh 11-14k (both vans are pigs) plus towing another 10k. Somebody could get killed if I am going too fast and lose control or if someone just pulls out in front of me like some idiots do. So I would rather stay at a safe speed whether or not the trans heats up. If our roads were going 80 I would go the back way. I would cause an accident not keeping up.

 

Maybe a stuupid question but here goes have you checked fluid levels when your running that fast.Your pump is probably at max flow capacity at 80mph not giving it time to cool in cooler.Maybe a deeper pan with more volume to add in cooling.

 

I edited my original post, the 80 is EMPTY.......short summary on the original post

75-80 mph empty = alot higher tranny temps
versus
towing 30K pounds at 50-60 mph......

 

A deeper pan will only make it take longer to heat up, but it still will. Pans don't cool, coolers cool.

As for the original problem, I think the cooler is partially plugged. At higher flow rates the pressure in the cooler lines increase because of the restricted cooler. Once the pressure hits 50 PSI the bypass opens and the hot fluid goes back into the trans, not to the cooler.

 

probably the torque converter clutch getting warm

 

i'd go with plugged cooler... i was going roughly 90 the whole way home on 287 last week (only like 30 minutes) and my trans temp never went above ~180 but of course it's cold out here...

 

I would also look into a plugged cooler but the E4OD doesn't have the cooler bypass like the 4R100

 

OK, since this thread has started I will add some more info & then yall can make some suggestions if I need to make any changes.

1. I very rarely drive my truck long-distances at highway speeds. The high temps. were only seen after a min. of 1 hr. non-stop with cruise set to high speeds........if I ever slowed down or ecitec the interstate temps would drop back down to 190

2. This past summer when I installed the tru-cool cooler I connected it in line with the stock cooler but did NOT install the thermal by-pass.

3. This fall when the temps began to drop my tranny temp wasn't getting about 130-135 driving to work (14 miles) and around the ranch pasture.

4. I had read somewhere that the tranny temp needs to get higher than than to evaporate the water that forms from condensation, or something like that.

5. I installed the thermal by-pass that came with the tru-cool cooler.

6. BUT, the high temps at highway speed was a problem WITHOUT the thermal by-pass

7. I thought it might help to plumb around the tank in the bottom of the radiator, which I did, and I think that may have helped some.


Thanks for all with suggestions and replies
ra

 

Could you possibly have some weird aerodynamics going on and your airflow across the cooler is not good at higher speeds?

 

It shouldnt matter. I would say you DEF have a tranny pump problem, or you placed your cooler in the wrong place IS iit in the FACTORY location on the front side of raioator? If so, keep reading. If not, fix that first. This could be a precursor for it failing. Here is my thought.

First, it shouldnt be the converter. It has a two stage lockup. The first is about a 30 % lockup that we hardly ever feel, and then total lock at about 40 mph depending. Once the converter is locked up, the ONLY way it will slip is if its bad, and shows with the more weight you put behind it. Second Your temps would sky rocket pulling even 3 k at 60 mph if it was even close to being bad. It would have to be a pump issue to not supply a 40 k cooler at that speed. As said, I dont believe that there is a cooler bypass on our trucks with auto. Your pump may be wearing that it can supply fluid at LOWER rpms, but then begin to starve the tranny for fluid at a higher RPM, AKA freeway speeds. Of coarse you should always make sure your Tranny level is correct first.

The only other thing that I can think of to give you a false reading would be temp sender location. If you have it installed in the pan, and it is int the front of the pan CLOSE to exhaust, , you may be picking up excess ambient temp from motor or said exhaust. This should give you a few ideas.

that being said, someone needs to figure out a way to get a pressure reading from the tranny pump. That would be a cool gague to have wouldnt it? tranny temp and pressure? That would be sweet......

 

Well, maybe but I don't think so. I posted this wanting to see what others here had observed with their tranny temp's

My theory is that tranny coolers are marketed for "towing" purposes but when compared to my data/observations it is that highway driving at high speeds (75-80) creates higher tranny temps that towing heavy loads at slower speeds (55-65), thus one might conclude that people with a vehicle similiar to mine who never tow anything may be overheating their tranny and causing premature failure just by driving at highway speeds empty for extended periods of time(more than one hour with cruise set). ummmm

Another supporting theory may also be that the stock tranny cooler was installed on my truck in 1997, I can't really remember but I believe in most states the legal speed limit was less than it is today.......

 

my dually at 70 mph with 410s is about 155 to 160. With 4100 pound trailer and 15k backhoe at 65 mph, its about 185 if its in the 60 or 70 s. You have a problem Houston.....