TR2/3/3A TR3B Oil Drain Plug

My oil drain plug seems to always have a slow leak/drip. I don't think that it coming from above. Is the plug supposed to have a gasket on it? I think that the drain plug is original. Will a new plug solve my problem ? Any help would be appreciated. Thanks.

Art

TR3B should have a plug with tapered threads, meaning no gasket is required or possible. But it's possible someone has fitted a pan from an earlier TR, which did use a gasket.

Assuming you do have the tapered plug version, I suggest cleaning and inspecting the threads. Damage is usually pretty obvious. You can use a suitable tap to clean up the threads in the pan; obviously replace the plug if it's buggered.

I'm not a fan of the factory plug, they seem very soft and prone to round off; plus lack a magnet. I use a hex socket plug (meaning you need an Allen wrench to turn it) with a magnet from MMC
https://www.mcmaster.com

Some teflon (aka PTFE) pipe "dope" will help the threads seal, and also make it easier to get out next time. Any place that sells plumbing should have it (Home Depot, Menards, Ace Hardware, OSH, whatever they have in your area). Eg, https://www.homedepot.com/p/RectorSeal-T-Plus-2-in-4-oz-Teflon-Pipe-Thread-Sealant-23631/100201204

Or if you want something more extreme, there is a Loctite product for sealing pipe threads:
https://www.amazon.com/Loctite-Strength-Thread-Sealant-White/dp/B000O03DLE

I think the plug is supposed to be a British Standard tapered Thread. If someone has put in a NPT plug, it will be prone to leaks. A new correct BSPT plug is an easy fix if that is the case. I'd get one with a magnet too.
Tom

Thank you. I see that TRF has the following oil drain plugs:

#14774 Plug, oil drain & fill, engine, gearbox $1.00

#155660 Plug, magnetic oil drain, engine, gearbox $4.50

Is this magnetic one a good choice ? Doesn't say if it is a BSPT plug though.

I got a magnetic plug from one of the major vendors (possibly Moss) but the magnet used was rather weak. I pried it out and substituted a rare earth magnet which does collect stuff (mostly a glob of thick oil that [probably contains some very fine metal).

I have since just added a rare earth magnet to conventional plugs - JBWeld works well for that.

One other benefit to the magnetic plug is that after you remove it and wipe it clean you can just stick it on the side of the oil pan - saves you looking for it later.

I tried the various thread sealers with no luck. What finally worked for me was permatex fuel reistant gasket sealer, comparable to blue hylomar. Drain oil. Thoroughly clean all threads (i used carb cleaner) both on plug and hole. Apply a very little hylomar to both plug, and hole. Screw in a few threads to spread it, then unscrew and let flash off (sit ten or 15 minutes until acetone odor is gone . Thread in plug, let sit 24 hrs. Then add oil.

TomMull said:

I think the plug is supposed to be a British Standard tapered Thread. If someone has put in a NPT plug, it will be prone to leaks. A new correct BSPT plug is an easy fix if that is the case. I'd get one with a magnet too.
Tom

Click to expand...

NPT and BSPT are different pitches in this size. A mismatch would not just be prone to leaks!

Since I've been using NPT plugs for decades, and no significant leaks, I'm fairly certain those threads are NPT. I do smear a little fresh pipe dope on them each time, but it's more to make them easy to remove next time than for leaks.

I will add that it's very easy to get fooled. A small leak higher up (like the pan gasket or fuel pump gasket) can be undetectable as it runs down; but form a very obvious drop on the lowest point.

One way to tell is to get some of that foot powder that goes on liquid and quickly dries to a white powder. Clean the area, then paint with the foot powder. It will change color if oil touches it.

I have no where near Randall's experience and don't remember ever replacing a drain plug, so just assumed they were BSP, but the point was that the the TPI and pitch on both are close enough in most sizes (3/8?) that either will screw into the hole, but of course cause a leak if mismatched.
That plug is one of the few places on my engine that I don't ever remember leaking. No sealant, dope, tape or goo either, so probably a good idea to look above it.
Tom

Thank you all. When I asked TRF if the plug was British Standard Tapered Thread I was told that it was "pipe" thread. Does that sound correct ?

I'm quite sure the TRF plugs are correct and same with Moss and the others and as Randall and others have been using NPT plugs, then that's what they are. My suggestion seems to have puts us off on a tangent. My point was new correct plug from a reliable source (TRF) would be a cheap fix or at least help with the diagnosis.
Tom

NPT stands for National Pipe Taper, which is "pipe threads" in the US.