Transmission drain plug leaking

[dockdoc]

Just started, apparently. Definitely gear oil, and I'm fairly certain it's weeping from the drain plug.

Found a previous thread where someone used permatex thread sealant - is this recommended?

The gear oil is new (1000 miles) since I did the frame swap earlier this year, but thinking since it's out I may put Red Line in as everyone seems to recommend. What's the right weight for the NV3550 gearbox? Having a little trouble getting into first gear (takes 2 tries a lot of the time) so wondering if this might help that.

 

[Jerry Bransford]

Redline MTL is a superb gear lube for your particular transmission.

Wrap the drain plug threads with white Teflon plumbers tape.

 

[CharlesHS]

Try applying a small amount of PTFE Thread sealing compound.
The paste is pushed further into the threads and seals better than the tape.
This is the compound I used for many years working with machinery.

 

[dockdoc]

Thanks guys - I think I’ll try the pipe sealant as I’ve heard the tape can sometimes get into the gearbox and cause issues. Probably not but whatever.

Redline MTL - just checking but it looks like it comes as full synthetic GL-4, 75W80 is that right?

 

[CharlesHS]

Thanks guys - I think I’ll try the pipe sealant as I’ve heard the tape can sometimes get into the gearbox and cause issues. Probably not but whatever.

Redline MTL - just checking but it looks like it comes as full synthetic GL-4, 75W80 is that right?

Here is what Redline has to say about their products:

Red Line Oil's MTL and MT-90 are designed to provide excellent protection and improved shiftability for manual transmissions and transaxles, having cured the problem of hard shifting in thousands of transmissions with shifting troubles. How? They have the appropriate coefficient of friction for most manual transmission synchronizers (many gear oils, engine oils, and ATFs are too slippery for proper synchro engagement). And, the wide viscosity of MTL and MT-90 allow proper shifting over the entire temperature range which the transmission will experience. The synthetic base oils used have a very high viscosity index which provides relatively constant viscosity as temperature changes. MTL is a low 70W at very low temperatures and a high 80W, nearly an 85W, at elevated temperatures, providing adequate viscosity to prevent wear and deaden gear noise. MT-90 is a thicker 75W90 version of MTL. The shear stability and oxidation stability of these products are excellent, thus the physical characteristics of Red Line MTL and MT-90 will change little with use.

 

[dockdoc]

Thanks all - ordered mtl and pipe sealant on Amazon, will swap it out and hopefully stop this leak this week.

 

[Jerry Bransford]

Thanks all - ordered mtl and pipe sealant on Amazon, will swap it out and hopefully stop this leak this week.

Common Teflon plumber's tape will absolutely work perfectly well for that leak. 50 cents a roll if you buy the good stuff. I own a container of the above recommended liquid pipe sealant but wouldn't use it for that kind of issue.

 

[MutantNinjaTJ]

I think I’ll try the pipe sealant

Why spend $1.50 when you can spend $15 and get the same results? Just sayin

 

[jazngab]

Reviving this thread as I used plumbers tape on the drain plug but it’s still weeping into a slow drip.

Any other ideas? I haven’t tried the PTFE thread sealant but trying to gather any other ideas before having to drain it again.

 

[macleanflood]

PTFE tape or blue Loctite. Maybe RTV.

-Mac

 

[CharlesHS]

I would inspect the threaded bung that the drain plug screws into with a bright light looking for hair line cracks where the bung attaches to the pan and also look for burrs or debris in the threads of the bung which can cause slow drip you are describing.
What do the threads of the drain plug look like ? Burrs, missing thread or debris in the threads.

 

[jazngab]

I would inspect the threaded bung that the drain plug screws into with a bright light looking for hair line cracks where the bung attaches to the pan and also look for burrs or debris in the threads of the bung which can cause slow drip you are describing.
What do the threads of the drain plug look like ? Burrs, missing thread or debris in the threads.

What is the solution to any of those scenarios, outside of cleaning any debris in the threads?

 

[CharlesHS]

What is the solution to any of those scenarios, outside of cleaning any debris in the threads?

If you find a hair line crack where the bung attaches to the pan; you can have the surrounding area of the bung either brazed or tig welded. If there is a hair line crack in the bung threads; that may require the replacement of the bung or purchasing a new pan.
Yes… if there is debris in the bung or the drain plug threads; thoroughly cleaning them should suffice.
If there is a problem with the drain plug threads; replace the drain plug.

 

[Link]

Any time I really want to seal some threads, I wrap the threads with teflon tape and then cover the tape with pipe dope. Never had a set of threads leak when doing that.

That said, I also agree with inspecting closely for cracks. There is no pressure in the transmission so it's not hard to seal on the threads alone.

 

[inkedrose]

This is all I could think of every time I read bung hole

 

[MutantNinjaTJ]

Doesn’t sound like pipe threads any more, probably the weld as stated above,

 

[Gilaguy23]

Redline MTL is a superb gear lube for your particular transmission.

Wrap the drain plug threads with white Teflon plumbers tape.

After you hire a fat fingered friend to plug the hole while you fix it that is.

 

[Rubiconned]

Wrap the drain plug threads with white Teflon plumbers tape.

And counterclockwise to the clockwise threads 3-4 layers.