Hei guys, once more.
My 1989 E4OD is having some troubles, I think. I was cruising the other day and my trans temperature started rising. I have a temp gauge in the pan. Usually it reads about 140-150°F when cruising without towing. The temperature started rising and at 190°F I decided to stop and cool the transmission down. When I drove again I found out that when I am not using the overdrive it cools fine (around 130-140°F). But always when I put the overdrive on the trans started heating, and no matter how fast I drove. I did not try to find out where it would level out, but it has never been hotter than 190°F. I guess that it would be OK to let it get even hotter, but this is a new trend for this tranny.
I have got a reading from the computer but it says that everything is OK, no errors. It also shifts fine and no sign of slipping. The trans fluid is clear and beautiful and does not smell burnt. Nothing is in the pan that indicates failure. I have an extra cooler installed.
Do any of you have any ideas what could be wrong? or am I just paranoid. Should I try to find out if the temperature levels out within a reasonable temperature range? How high do you think I can let the temperature in the pan go?
Thanks in advance, Bjarni

 

Just driving around town after a long drive, temps should stabilize somewhere between about 180 and maybe 200 but leaning towards the 180 unless it is really hot or hilly.

A tranny takes a long time to come up to temperature, at least an hour of freeway speed and sometimes more. So if all your trips in the past were short and cool, then your tranny may not have gotten up to the true operating temp.

I would probably run it on a 2 hour drive and see if the temperature stabilizes below 210 or not. If it starts to creep towards 230 then something is definitely wrong, especially considering you have an extra cooler. BTW I think 210 is still a bit too high, but within normal. Lower is better up to a point.

NOT being a tranny expert, my guess is that if you have a lockup converter, the lockup clutch is starting to go. If it is a standard converter, then either the converter is failing in general or the clutches in the tranny are starting to slip a bit.

Or perhaps you have gotten some blockage in the coolers. Overtime you might get a bit of sludge deposit in the coolers. Recommended maintenace at a dealer often includes a cooler chemical flush, I've seen this in several Shop Manuals. Some shops just put in a new cooler.

Since it sounds like this just started to happen, unless there is something you are doing different from before, I would guess the tranny is getting ready to do something.

Good Luck,

Jim Henderson

 

Thanks Jim.
I went for a spin the other day and after about an hour of cruising in overdrive, the temperature leveled out at about 200°F. It was fairly flat terrane. The ambient temperature was about 65°F. I am happy that it does not seem to be overheating at the moment but I think something is wrong, even though the shop has not found any problems. I put a bottle of Lubeguard (recommended by the shop) on the tranny to see if that might help "loosen" something within the tranny.
Regards, BR