I have a 72 Riv with a rebuilt (less than 1000 miles) TH400 that is leaking in a strange way. I do not drive the car very often but when I do it shifts smoothly. A few weeks ago my wife sent me some pics of trans fluid spreading out on the shop floor from under the Riv. When I came home I jacked the car up and looked for an obvious leak... nothing. I cleaned up the mess and subsequently noticed it leaked more fluid. Next I checked the dip stick and saw there was a little at the end of the stick, but well below the add mark. I added 1.5 qts of fluid, drove the car around and haven't seen a sign of the leak since!!!! I have an appointment with a trusted mechanic to put her up on a lift and check it out, but why isn't it still leaking after I added fluid?
When you shut the engine down, and leave the car sit, oil drains back OUT of the converter and raises the pan level. A common leak point is the O ring for the dip stick tube. If the level in the transmission is correct when fully warm, it will be way up on the stick after the car sits for a day. That is why you check the level with the engine running.
Thanks for the input. Yes, I ran the engine until it was warm and then checked the level/added fluid. Now the stick indicates full after driving her, but the leaking stopped...???
There are other leak points like the case connector and speedometer sleeve seals that worsen with converter drain back. The filler tube O ring is a likely one though. Oil leaks are hard to figure out. Clean the case really well and then watch.
The Wildcat will spit out a qt + after a drive. Hardly leaks anything while moving but let her sit over night or a few days and theres a stream of fluid running out from under the car. So much so that I'll take a clean drain pan and slide it under the inspection cover when she gets parked and when ready to go again will pour it back into the trans through a funnel with a painters filter in it.
In addition to Larry's items. When sitting or running, shifter shaft seal, modulator, governor cover. When running/driving, and may be small puddle after driving from residual of these leaks. Cooling line fittings, front and rear case shaft/hub seals, pump seal/o-ring. Rarely but also possible, the pressure test port plug, vent tube, tailshaft housing, parking pawl shaft cup plug. If you have a leak and until it is diagnosed or fixed, keep a close eye on fluid level. Low fluid will lead to loss of effective pumped fluid, low pressure, and cascading failure.
The problem is converter drain back. Now you have to find out where it leaking out. Mine was leaking out of the shifter seal. Most shops forget about this one. I would wait until the leak occurs again, then add more fluid, and observe where it leaks out. Don't start the engine before doing this.
The case connector orange and shift shaft seal both are hard to track...they look like pan leaks since they are about the same height as the pan. If the shsft seal they make a tool to replace it externally and it takes just a few minutes....... the case connectir o-ring requires pan to drop
The shift shaft seal can also be affected by drain back. Change the shift shaft seal and the dip stick "O" ring and the problem will probably go away, cost $10 and about an hour of work.
I have had this problem for years. I can't (and two transmission shops) find the leak. This is after a complete rebuild. Very vexing problem.
Anybody ever hear of Case Porosity? Apparently enough of a problem that it is mentioned in the Chassis Manual.
Thank you for all of your inputs! I'll let you know what the mechanic finds once he gets her up on a lift.
Yes, its coming out of SOMEWHERE. Too many "mechanics" arent They dont want to spend the time to investigate, otherwise they feel stupid, like its a waste of their time, unless the oil is squirting out and obvious, "I dont see a leak" Too many "mechanics" think they're awesome, and if they have to slow down, and use logic to fix something, they're afraid they'll look "Not awesome" My T-350 had a shift shaft seal leak before Vince Janice rebuilt it, after the rebuild, it was leaking from the dip stick tube O-ring (my fault) All leak free now. first time since 1985 Do this yourself, spray gunk on trans, its easy from both sides, no need to crawl under car, rinse off. Drive car till hot, park in garage over clean cardboard, see if its one or multiple drips. See the drip or puddle on cardboard, go straight up to trans case and see if theres any fittings or linkages that protrude thru the case, if not, investigate going FORWARD on the case and look for a fitting, seal, linkage that protrudes thru the case, yes this is where many "mechanics" dont want to spend time to investigate, or use logic The oil is leaking from SOMEWHERE
A buddy of mine worked at a Chevy dealer back in the 80's. A customer insisted that he had a transmission leak because there was always fluid on the garage floor where he parked. After multiple complaints to the dealer and no leaks found, they finally just installed a new transmission. Later, the customer came back to the dealer and apologized. It turns out his wife had a boy friend who's car had a transmission leak.
Good advice! Thanks Mark. I just trailered her to MN and put her in storage until I retire next spring. Once we get settled in our new retirement home, I’ll do as you suggested.
