Trans Leaking When Sits To Long

[FOR MUD]

I have a TH350 trans that leaks if I let the truck sit for more than two or three weeks . If I start the truck and let it warm up the leak goes away . Also theres no leak when the truck is running just when sitting . I changed the filter and gasket about 10 hrs ago hoping to stop it . If it is the seal why doesn't it leak when running ? What seals the pump to the case ? The trans works fine so I don't want to rebuild it until something bad happens .

 

[1985_K5_Silverado]

Seals can dry out and shrink a little when the machine just sits for too long, but have the seals again become normally flexible after being used for just a little while. You see this with winter-stored Vettes and other fair-weather collectible cars here in the rust belt - many owners don't take them on the roads until the road salt is all washed down the sewers by spring rainfall, and a lot of times, they wind up with quite a red puddle under the car when spring arrives.

If they can, it's not a bad idea for the winter storage types to start the engine, drive the car back and forth a few dozen feet in the driveway, shift the auto trans through all the gears, the transfer case, and just keep everything freed up every week or so. If parked outside, this is an especially good idea, because you wouldn't believe the critters that sometimes think your exhaust pipes are an appealing place to set up housekeeping.

 

[FOR MUD]

I had a rat make a nest on the engine of a truck at work , man did it smell bad when it started up . I guess I'll try replacing the seal it's a pian to do all that work for only one seal !! Maybe I'll change the rear main too to make it worth it .