View Full Version : Leak at Oil Drain Plug

04-21-2012, 05:35 PM
TR4a Leak at drain plug:

Last year I had the plug "braised" and fixed, so I hope I didn't crack it away again. I'm assuming it's leaking right thru the threads.

Does that usually need teflon tape? Is a leak there really all that common?

04-21-2012, 06:14 PM
The braising may have distorted the threads until they won't seal easily.

Rather than tape, I use teflon paste.

https://www.homedepot.com/buy/plumbing-pl...ste-188047.html (https://www.homedepot.com/buy/plumbing-plumbing-accessories-pipe-cement-primer-cleaner/william-h-harvey-company-16-oz-tfe-paste-188047.html)

I also prefer to use a magnetic hex socket pipe plug (I get mine from MMC). They are hardened and thus much less likely to round off than the standard square head plugs. If you do keep the square head, at least get an 8-point socket to turn it.

06-15-2012, 07:41 PM
I'm headed to Home Depot now. I'll report on the Teflon Paste. Nothing else works.

Andrew Mace
06-15-2012, 09:20 PM
Sorry for this, but I gotta know: did you really have the plug "cook[ed] slowly in fat and little moisture in a closed pot" (Merriam-Webster definition of braised), or did you have it "solder[ed] with a nonferrous alloy having a lower melting point than the metals being joined" (Merriam-Webster definition of brazed)? :devilgrin:

06-16-2012, 12:14 AM
My pan was repaired using some form of brazing, copper or brass. Thanks for the spelling correction.

06-16-2012, 07:28 AM
Why not put a little non-hardening, oil-resistant gasket seal on the threads? I'm not suggesting this... just asking.

06-16-2012, 07:56 AM
Don't know TR-3s, but if the plug has a flange on it for a washer gasket seal and leaks because the base is distorted, slip a snug fitting, thin O ring on it instead of a washer. PJ

Geo Hahn
06-16-2012, 09:26 AM
Works on many engines (e.g. my VW) but the TR plug is a pipe thread (taper) that does not rely on a lip to seal.

06-16-2012, 09:29 AM
You might try a softer copper washer. I have always had good luck with teflon tape. They make an oil resistant teflon tape. Another great sealant foe many applications on engines is Seal-All. https://www.kk.org/cooltools/archives/001586.php

06-16-2012, 10:03 AM
Works on many engines (e.g. my VW) but the TR plug is a pipe thread (taper) that does not rely on a lip to seal.

That's true for your and KVH's TR; but not for TR2 and early TR3. They used a flat head plug and a fiber (softer than copper, seals easier) washer that needed to be replaced from time to time. Parts book gives the change point as engine 18902E, but since the oil pan will interchange otherwise, it may be possible to find one of those earlier pans on a later engine or vice versa.

The teflon tape/dope is not really a sealant as such; its primary function is to act as a lubricant so you can tighten the plug more. The extra tightening deforms the tapered threads so they fit together better and that is what improves the seal. There are products that act as sealants, for example Loctite PST works well, but they also make it harder to get the plug out next time.

There are also various kinds of rubber repair plugs available at your FLAPS. I used one of the expanding rubber plugs for quite a few years on my TR3A (which had an earlier pan with the flat plug) and it did work OK (although it was messier to remove it to change oil).

06-16-2012, 10:38 AM
Correct on Randall remark regarding the teflon tape. Esp if
there's oil in the threads. Look at Pegasus racing page 95-97.
They have copper, aluminum, nylon crush washers. Also have
Dowty seals. Use these all the time in my racing application
with great success.

06-16-2012, 11:25 AM
I guess it depends on how bad the leak is between the threads but Permatex #2 or one of the Hylomar's work pretty good as a thread sealer and should not act like a thread locker if you remove the plug to change oil at least twice a year.

06-16-2012, 12:32 PM
I would respectfully disagree on the teflon tape not being a sealant.If you wrap typical pipe plug,it will even usually seal when just snug,as the tape is more like a ribbon packing of teflon.
Thats why in a pinch it makes good valve stem packing,just like graphite ribbon tape etc.,and why a leaking ferrule,even new say 3/8 plumbing ferrules will stop leaking with a couple wraps and require less tighnening.No lubrication is involved,just a layer of packing material around the ferrule,to crush on the seat.