I'm having problems with the drain plug leaking in my 80. It has a 1/2" DO-20 plug in it now. It dosen't seat flush is the first issue. I have tried the plastic gaskets and copper with no luck. Do they make that size plug with an OEM type modern plug with the rubber already in it. Any other ideas I can try?

 

Why yes. Try telling us which drain plug you're having the problem with. Engine oil, transmission--manual or auto, differential and what model year...all C3's are not created exactly the same.

 

It's the oil drain plug and it's an 80 like I stated above.

 

You need to get the outside surface of the pan [around the drain plug] flat. If it's not, no matter what you do (short of putting sealant on the threads of the plug), it won't seal. Next time you drain the oil, clean off the surface around the plug and work on it to get it flat.

If it has depressions in it, use a Dremel or pick to clean out those 'divots' and fill them with a polyester body filler or JB Weld epoxy. Once you get a surface to work on, use vaious grades of sandpaper and a small wood/metal block to create a flat surface and as 'square' to the threads as you can make it. You can always stick the plug into the pan and use the flange as a 'gauge' to judge how square that surface is. You don't need it super smooth for it to seal...it just has to be flat & square.

I would recommend getting a rubber coated metal washer to fit under the plug flange, rather than a hard plastic washer. Put a little wipe of grease on the underside of the washer so it doesn't grip the pan surface and tear as you are tightening the plug. And don't tighten any more than you need to seal it.

BTW, I hope you are using a drain plug that was made to be a drain plug. Only those will have a flange that is machined flat and perpendicular to the thread centerline. If you aren't using a 'real' drain plug, that could be your problem right there.

 

Cross threaded maybe?

 

It's a real drain plug that I'm using. It's not cross threaded. I didn't notice it wasn't seating flat until I looked at it on a lift. Are there any good aftermarket pans that would fit on an 80 with a right hand dipstick? Otherwise I'll try and get mine flat so it seals.

 

The baffeling in this one seems kinda close to what mine looks like. I looked at a few aluminum pans and some had no baffels at all.

http://www.summitracing.com/parts/TRD-5101/?rtype=10

 

You have a PM.

 

Thanks!

 

Hmmmmm. Secrets, eh?


Keep the shiny side up!
Scott

 

I know this isn't a fix, but would a little thread sealer be okay on the plug?

 

Thread sealer is not a good solution here. Generally thread sealer is used on pipe thread fittings where the seal is made by the threads. Thread sealer is also used on bolts that penetrate into areas exposed to oil or coolant, but these are bolts that are torqued and not disturbed again.

Generally engine oil pans have a straight threaded plug that depends on a gasket because it is removed on a regular basis.

The correct fix is to get the pan seating area flat or replace the pan. A few well placed blows using a hammer and a large diameter punch may help. (Unfortunately poorly placed blows may make it worse.)

On Edit: Re-reading your post, sounds like you are curious for a temporary solution. I still wouldn't; your likely to get some sealer into the oil pan and contaminate the oil. I would rather have a drip than sealer swimming with the oil.

 

First option
Go to ACE hardware and get a couple of neoprene washers that fit the drain bolt. Get the id snug and trim the od.

Second option
Got to a parts store and get a drain plug of your choice (modern one with rubber washer) a hair bigger than the original, doesn't matter if it's sae or metric.
Get a tapered or starter tap and rethread the pan for the new bolt. If you hold a larger nut that's the same size it will help you rethread it straight. The backer plate in the pan is more than big enough for this.
You can use a bit of grease and a neodymium rare earth magnet on the tap to collect the shavings. Then flush the pan with some cheap oil without starting the engine.

Done lots like this.

 

Thanks for all of the ideas guys. I will try the neoprene washers first as a temp fix until I decide if I want a new pan or just fix what I have.

 

with option #2
Short of replacing the pan, this is the one I have done over the years.
Good luck with whatever you choose.

Bman

 

I may add that if you have a good drain bolt (flange bolt) now and it is not cross threaded etc, you can put some grease on the pan and the flange of the nut and tighten it as much as you can and it should straighten out the mating surface. Tighten smack head with a hammer, tighten, repeat. It should get it close enough for a washer to seal.

You don't need to replace the pan over this.

 

Camss57, have you ever given this device a thought? Because once you install it and determine there are no leaks, it's permanent.

http://www.oildrainvalve.net/