I had my E4OD rebuilt at AAMCO after the torque converter went out during a trip to Florida. I chose to have updates done (billeted torque converter, steel planetary gears, shift kit) and even a larger cooler. It seemed to go well (no leaks, shifted fine, done on time). After driving 200 miles I was certain it was getting hotter (30 degrees more under similar circumstances) than before the rebuild. I called the shop where it was done and stopped at the next AAMCO to have it checked. They suggested it could be the new parts (steel planetary gears holding more heat) the thermostat sticking (the gauge in the dash display still reads the same as before the rebuild, although I don't know how accurate it may be), or dissimilar circumstances in weather and drive. I went ahead and drove home to Colorado (babying to stay under 230 degrees). I am convinced after driving on familiar roads that it runs at least 25 if not 30 degrees hotter than before the rebuild (instead of 195 @ 65mph and 75 degree weather it is running 225 and would go higher if I drove more fast). I made plans to have it checked out at AAMCO in Boulder. I asked about testing it with a flowmeter to see if the pump was working correctly (have to ask the tech later) because I watched the disassembly and noted that the pump was out then replaced and scribed for reassembly (was it fumbled?). I am not an expert but the previously mentioned reasons for extra temp don't add up to me. That is why I have logged on here with this loooong question. Thanks in advance for any expert opinions I may recieve, Garth

 

What year is your truck?

 

Something ain't right, Bubba! You don't say if you were towing or not, but my tranny runs at 165° tops when pulling a trailer over the Cascades in August. Around town, running empty, I barely get to 130°. I'd wonder if you're getting any circulation from the pump, and whether the "cooler" is doing you any good.
If it's a E4OD, it has to be an OBS* truck, and I don't think there were any significant changes to the tranny between model years, but I could be wrong.


*OBS: Original Body Style

 

certain years of these trucks have an external bypass on the and they can get stuck and will not circulate the fluid thru the cooler. I have had this happen to a few customers after a rebuild, the tranny shops dont think to replace this 25 dollar part for the headaches that they can cause. Also did they replace the cooler with he same size or larger.

 

My truck is a 95 F-250 crew cab, PSD 7.3 and it hauls a truck camper that is quite heavy. Sorry I didn't include that fact. I know I am asking a lot from it. The rub is, that it was at an acceptable temperature before the rebuild. I couldn"t quite make out what part may not have been replaced. Thanks for the quick replies. Garth

 

CLK, The cooler is larger (8"X12"). What is the external bypass on? How can the flow from the pump be measured, or can it? I thought something weren't right Quadzilla, thanks for affirming my feelings. I guess I shouldn't have thought AAMCO would agree with me! Garth

 

you state that the trans gauge reads the same. how is it that you think it is 30* hotter?

or do you mean the temp gauge for the engine?
if so then maybe the larger trans coller is blocking flow from the radiator and not letting it cool properly.

 

just installed a trans gauge on mine and it barely hits 140* after and hour of driving. very cold here and have not towed w/ her yet since.

 

I said:
CLK said:
See? I told you I could be wrong. Thanks for clearing that up, CLK.

 

18vtx00, Opps, I should have said engine temperature gauge reads the same.
The after market trans temp gauge reads higher than before rebuild (I took the readings very seriously since I knew the extra weight could really affect transmission) . The factory engine temp gauge reads the same as before the rebuild. I am sure of this because (maybe I go to far, but) I marked where the needle was on the dash display at a time I thought things were normal. Since the engine temp reads the same as before the rebuild I assume the trany cooler is not blocking air flow enough to raise the engine temp and therefore the trany fluid temp since it passes through the radiator. Still, I am not certain how accurate the factory gauge may read. I am also not sure whether the cooler is in line before or after the radiator (I am glad to check it out if need be). Kind of gets complicated to me, sure need more info on how it all works. Waiting to hear more from CLK, for sure. Garth

 

I pull a 10000 fiver in South Texas heat with my 96PSD, if my tranny temp ever got 210 I would panic. You definetly have a problem.
Just a thought is there a filter in you cooler circuit it could have gotten plugged by debris things disintigrated when it went out

 

There was not much damage to the transmission itself since we watch the gauges carefully and stopped immediately and got a tow. I have not seen a filter in the cooler circuit but may not know what to look for. Wondering how poorly transmission fluid is pumped when part is put in wrong position and how to measure flow. Seems most likely problem to me unless CLK's external bypass is to blame. I started to panic until reading fluid starts to varnish at 240 degrees and worse things come somewhat later. I was very carefull to stay below 230. Thanks for your support of my concern, Garth

 

Sorry it took me so long to respond. I cannot remenber which years had the eqternal bypass on them, but it is a tube that goes between the inlet and outlet ports of the cooler lines. It lets the fluid bypass the cooler until the tranny reaches a certain temp, about 80 deg. There is a small thermal valve in these that will partially stick open and not allow all of the fluid to go thru the cooler. It a simple part to replace but it has caused many a headache. The cooler size on yours sounds fine, a true cool max would be better 8"x20", this is what we install on all of the trucks that customers are going to use alot for towing. hope this helps let me know

 

Oh, by the way transmission fluid is parafin based and it will loose half of its lubricity properties if it goes over 230 deg once.

 

I took my bypass off after my first transmission rebuid. The 99' and newer transmission's require that a external filter be put on for tranny warrenty.