BlitzSRM

I finally got around to changing my transmission fluid to the GM sychromesh. When i finished and cleaning up my oil pan, i noticed an aluminum washer. i check ant it is for the drain plug. I had already put the fluid in, and the car was ready to go. I figure it would be okay, just check if it leaks. i saved the washer for the next fluid change.

I was thinking of reinstalling it next time i change trans fluid, probably another 30,000mi. (it was clear, when i drained it and seem like it was still in good condition), but i was also think of removing the bolt real quick put my finger on it, place the washer back on the bolt, and quickly installing it again. but i'm not sure if that's worth it.

but i remember xviper's right up, talking about galvanic bonding of the bolt and casing.

has anyone ever forgot to put it back? for those that did, any leaking problems? or problems removing bolt when changing it again?

xviper

I think you would be best to do this. Then top up to make up for what you lost.

"Galvanic adhesion" is most evident when the mating surfaces are completely flat. Without this washer, you can't be sure of this. It's not just the ability to seal the hole but the washer is slightly compressed and this applies a backward force against the bolt to help it stay in place. Without it, there is a risk that over time, the car's vibration may work that plug loose. Not something that would have a happy ending.

BlitzSRM

I figured checking it in a couple of weeks, to just look for leaks. But i never actually thought about the bolt completely comming off

BlitzSRM

I think i'll jack it the Right side up as high as i can, and maybe there won't be any fluid loss...

yeah that's what i'll do.

xviper

Actually, the casing will hold more fluid if you jack it up on the left side. That's where the holes are. However, you'll never jack it up high enough to prevent any fluid from coming out the drain hole. Just be quick with your finger and have a helper to dry the bolt and put the washer on for you while you have your finger in the dike.

Scablander

By the way, be sure the transmission is cool before you do this. Please don't ask how I know.

BlitzSRM

o yeah xv, the left side...duh

scblander, alright i won't ask.

Utah S2K

You F***** up! Pay the price, drain the transmission and do it right. It has nothing to do about Galvanic Corrosion. It has to do with the stress on the transmission housing threads and thermal cycling. By the way the GC discussion is mute as the pan and crush washer are both aluminum.....

Utah