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MG MGB Technical - Do you put anything on drain plugs?

Wondering if anyone puts any sealer on their drain plugs in the diff, and trans.

I note in my GT with OD, that I still get a tiny amount of oil that finds its way around the plug threads even when very tight.

When I rebuilt my TD trans at a rebuild workshop put on by John Twist, he used a very light coating of silicon on the drain plug.

I would be concerned about something getting into the OD system, but just wondered if there might be something that would seal the threads better.
Bruce Cunha

PTFE plumbers tape? I have never used anything but if mine leaked that's what I would try.
Mike Howlett

How would silicone stick to the oily threads of the plug but also the drain hole? I'd second Mike's suggestion.
Michael Beswick

Should be tapered threads and shouldn't leak. Never used anything in over 50 years of car maintenance, and that includes never annealing or replacing the copper sump washers which is something else that is advised from time to time, and never had any of them leak. If you have a leak, then it's possible one or both threads is damaged, so you could try PTFE. Never Silicone.
paulh4

PTFE tape. It was designed to seal screw threads, particularly BSPT and similar taper thread plumbing joints.
Allan Reeling

Are you sure it's the drain plugs that are leaking? They are the lowest point on the diff/trans so any oil leaking higher up will collect there before falling off.
M Ratcliff

Excellent point on if it really is the plugs that are leaking. Cant find any fluid above the bottom of the trans. Just a very light bit of oil on the bottom.

Transmission plug appears to be pipe thread. Very course. Threads appear good. Teflon tape should work for this.

Plug on the OD (D type) is also course thread.

I had my concerns on silicon also, but when you go to a transmission rebuild class and John Twist says to use a light coating of silicon on the plugs that can leak, you take him at his word. In that case, it is put on after the rebuild, so no oil on the threads.

John also said that after his rebuild class, your transmission will not leak. He had us flatten all plates and mating surfaces. Got to say, no leaks in the TD transmission.

For the B, think Teflon tape makes more sense.
Bruce Cunha

Bruce-
I know that I'm late to this thread, but please note that white PTPE Teflon tape is inappropriate for this application as exposure to hydrocarbons, such as gasoline (petrol) or oil will cause it to dissolve. Instead, use yellow PTFE Teflon tape.
Stephen Strange

Thanks Stephen. Good point. I did us the petrol resistant type.
Bruce Cunha

Loctite 561 is the answer for thread sealant - it is an anaerobic setting material that fills any voids between the threads and is oil and fuel resistant
http://www.loctite.com.au/3320_AUE_HTML.htm?nodeid=8802629746689
Mike Ellsmore

I have a 1977 OD transmission. It was lossing about a quart of oil every 15,000 miles for a couple of years until I finally figured it out. I cleaned off the oil on the trans and drove it a mi!e or two. Then I looked and saw a bit of oil on the drain plug. Next I replaced the drain od's drain bolt washer and it has not leaked since. That was over 4years ago. The drain bolt has machine thread, not pipe. Hope this helps.
jrb Ross

That's the relief valve plug, not strictly a drain plug although it may have that effect. The OD is normally drained by removing the tapered plug in the gearbox. care should be taken if removing the OD relief valve plug, as it is retaining myriad parts.
paulh4

You are correct Paul H, the washer on the relief valve plug was what I replaced to stop the leak. I actually used an aluminum washer for a Honda drain plug.
jrb Ross

This thread was discussed between 07/03/2017 and 09/04/2017

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