under water

on inspection of the gear lube in the 3 speed trans I found evidence of water in the gunk that had settled by the drain port. How can I flush the tranny without doing damage to the seals. I was considering flushing with mineral spirits then installing new oil and running it around the block and changing it one more time. With my fiberglass tub I don't think i can remove the top shifter cover very easy to use brake cleaner as mentioned eleswhere.

 

I have used ATF to clean an engine with stuck lifters before. i don't see why it wouldnt help clean your 3 speed. add half a quart with some good gear lube and run it for a few miles. then change it out again. it is high in detergents to keep the valves in an automatic clean enough to function.

 

Pull the plug and drain it. leave the plug out for a day or two. Fill the trans, drive and drain. Drain it as soon as you finish driving everything will be mixed up. Do this a few times

Steve

 

I've used diesel fuel to flush boxes. Drain contaminated oil out, fill to the proper level or slightly higher and run a few miles then drain. I usually let it drain for 20-30 minutes then refill with the proper oil. Never had any problems with the seals leaking.