Trans pan plug will not seal

[OrrieG]

I bought a new aluminum trans pan for the 350. And installed it last year. It came with a 1/2" NPT plug that I cannot get to seal. I've tried silicone tape, and Permatex thread sealer. I have cranked it as tight as it will go, it has tapered threads. It still is weeping.

Any ideas?

[entourageguy]

Does it need a fibre gasket like an oil pan drain plug?

[OrrieG]

No it is a pipe thread that does not use a bolt with a gasket. I reinstalled it last night using a new plug (brass) and a different "tacky" sealant. If it is not leaking tonight I will paint the brass black and call it good. I called Summitt and their comment was that it was designed so the plug would be flush with the pan. They said it sounded like a problem with the pan threads and that I should drop the pan and get the hole retapped. Their second recommendation was the tackier sealant. Dropping the pan will be a pita because of the cross member and I don't even know if it will clear the intake so I can drop and slide it back. Plus restallation would be really interesting. I told them that if I dropped the pan I would just install the original leaking plug and have it heli-arced and ground flush, this is the first pan I ever had that had a drain, I can go another 45 years without one!

[Fred T]

Get a tube of Permatex Hylomar. If that won't seal it, nothing short of JB Weld will work.

[CAL 58 GMC]

Mine has a nylon washer on the plug.

[OrrieG]

Thanks, and I have plenty of JB Weld, that and bailing wire and duct tape have gotten me back home many a time.

[OrrieG]

Originally Posted by CAL 58 GMC

Mine has a nylon washer on the plug.

That is what I expected when I bought it, is your 3/8 NPT or standard bolt thread?

[Atomsplitter]

OrrieG,

You should never need tape for the plug as it should be a straight thread anyway. It seals with an o-ring or a ring seal of brass, compressed fibre, plastic or rubber. There should be a flat surface on the pan around the hole for the seal to sit.
The drain plug on my '95 Cutlass had an o-ring molded into the edge of the plug

[OrrieG]

I know it should bestraight threads with a washer/bolt but it came tapped for a 3/8 NPT tapered threads, somebodies better idea. It looks like the stickum worked so issue is resolved until its time to change the fluid. Thanks for all the comments.

[OrrieG]

It's been a week or so and the tacky sealant did the trick. The plug that came with it does not have the same depth of threads, looks like it was manufactured a little less diameter so the male threads did not go as far into the female one thus the leak.