Transmission Heat

[Butcher52]

I just recently put a rebuilt 700r4 in my truck and it seems like it is running kinda hot. I can feel it puting off heat through the floor while going any speed above 20mph. Also, I do not have any insulation other than factory insulation. I was just wondering if this was normal or if I have something to be woried about. If so what can i do to fix it?

 

[bucket]

Heat in the floor would normally come from the exhaust. A trans temp gauge is never a bad idea if you have a 700r4.

 

[philjafo]

If your trans is overheating don't drive it until you fix it. Overheating will kill a transmission very fast, almost as bad as driving with an incorrectly adjusted tv cable.

 

[Butcher52]

Heat in the floor would normally come from the exhaust. A trans temp gauge is never a bad idea if you have a 700r4.

I did think about that but I have had the same exhaust in for about 5 months now and havent noticed it. I will try to put on a trans temp guage on soon.

 

[Butcher52]

If your trans is overheating don't drive it until you fix it. Overheating will kill a transmission very fast, almost as bad as driving with an incorrectly adjusted tv cable.

Could the tv cable being adjusted wrong contribute to the heat? I did mine myself, but all of the shift ponts are correct, including the downshifts.

 

[philjafo]

I don't think so, not certain but if it shifts ok the cable should be adjusted right. You mentioned its a fresh rebuild, did you flush a solvent through the trans cooler? Do you know what killed the old trans? You could tape a simple thermometer to the metal line and get a trans temp. I can never remember which is from the trans-cooler and which is cooler-trans, checking both will tell you temp drop across the cooler. IIRC ideal temp for a transmission is 170*, the factory put the cooler in the radiator to get it to that temp quickly. It works good too unless it gets dirty inside the radiator side and can't transfer the heat to the coolant.

 

[Butcher52]

I didnt not flush it with any solvent however I did drain it as best I could and used an airhose to get some of the old oil out. Also, I put an extra external filter on to catch any extra things I missed.

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This is what killed the old one. I think some of the rear pin bearings broke and got chewed up by the gears then thrased the rest of the transmission. Not sure why it happened other then that it was old and hat to many miles on it.
I will check the temp with thermometers tommorow and see what I find.

 

[philjafo]

Is the flow direction through the extra filter going the right way? The bottom of the old pan looks nasty, did you reuse the old torque converter? If yes there is a good chance your filters are plugged, there is a lot of fluid in a torque converter impossible to clean. Does you extra filter housing have a thermostatic valve in it that may not be working correctly. My first suspect would be that extra filter, try bypassing it to see if the problem goes away. If it does cut the filter open to see if its plugged, if its not plugged try reversing the flow through it.

 

[chengny]

I didnt not flush it with any solvent however I did drain it as best I could and used an airhose to get some of the old oil out.


Dude! You have to shut down now - and thoroughly flush the ATF cooler section of the radiator.

Neglecting to flush the cooler (and check for proper flow rate) after a catastrophic transmission failure almost assures that the replacement unit will not last long at all.

If done right, a thorough transmission cooler flush is involved, time consuming, uses a lot of solvent/rags and is expensive. Unless you have a lot of time on your hands, it may be a good idea to just get a new radiator and be done with it.

Use the time saved to drop the pan and change the ATF and filter even if they were new when you installed the transmission.

Did you dump and flush the contaminated ATF that was left in the torque converter after the failure? It's too late now but, most of the ATF in the system is in the torque converter.

The filter was the right intention but there is a good chance that now, due to the amount of particulates remaining in the system, it is plugged. That also contributes to a low flow through the cooler. Take it out or change it.

 

[Butcher52]

Is the flow direction through the extra filter going the right way? The bottom of the old pan looks nasty, did you reuse the old torque converter? If yes there is a good chance your filters are plugged, there is a lot of fluid in a torque converter impossible to clean. Does you extra filter housing have a thermostatic valve in it that may not be working correctly. My first suspect would be that extra filter, try bypassing it to see if the problem goes away. If it does cut the filter open to see if its plugged, if its not plugged try reversing the flow through it.

The flow direction is correct I checked it and double checked it, and the torque converter I used was brand new. You may be right on the extra filter being cloged up, i meant to change it after a few days of driving but it has been a few weeks, if I get some time today i will do that as well as checking the temp.

 

[Butcher52]

Chengny, I put the external fliter on the cooler just for the reason of catching any particles that did not get out of the system and the torque converter i used was brand new. If i were somewhere i could wourk on it i would take your advice and drop the pan and change the filter, however the ATF fluid has been changed.
I will post some pictures of my set up later today.