Gearbox oil leak

[crankedup]

My vintage car (1925) has an bad oil leakage due to the fact that the drain sump bolt has no washer or gasket. The drain plug is a solid brass threaded into an alloy sump, both threads are fine and present no problems there. My question is that I have just tried a blue instant gasket which did'nt stop the leak, any suggestions as to the best material to use for a washer/gasket? Thanks.

[Steve_D]

Copper would be my first choice followed by fibre as second choice.

If it's really old leather may also have been used but I would not recommend it now.

Steve

Edited by Steve_D on Monday 21st July 17:38

[crankedup]

Thanks Steve, so simply a flat copper washer then thats a snug fit?

[Daveuk9xx]

crankedup said:

My vintage car (1925) has an bad oil leakage due to the fact that the drain sump bolt has no washer or gasket. The drain plug is a solid brass threaded into an alloy sump, both threads are fine and present no problems there. My question is that I have just tried a blue instant gasket which did'nt stop the leak, any suggestions as to the best material to use for a washer/gasket? Thanks.

You should be finding out exactly why it leaks first. If the flanges on both sump and bolt are flat and clean it shouldn't even need a washer against aluminium. Is the bolt designed to be used with or without a washer, i.e does it have a sealing face under the head or is it bottoming out on a radius between the stem and head leaving a gap between sump and bolt? If it's a "bad leak" then there must be a very obvious cause.

Once you know why it's leaking and how it was designed then you can fix it. Maybe the sump or bolt flange need resurfacing first if they are damaged or not true. Sump washers are usually nylon or crushable copper. Brass or aluminium can do just as well against clean surfaces though.

You should be able to find something suitable here unless it's a very odd size.

http://www.jrpdistribution.co.uk/acatalog/Sump_Plu...

Dave

[stevieturbo]

Use a Dowty washer/seal.

[crankedup]

Thanks guys, Dave all I can say is that the brass sump plug is threaded on most of the shank except the area immeadiately below the bolt head. So an unthreded length of about 1/4 inch or so. The base of the nut is flat and the gearbox mounting has an flat ringed area where the bolt tightens up to. Sorry its difficult to explain. Oil loss is about a pint per month maybe slightly less and leaks hot or cold.

[crankedup]

All sorted now, found a slight bit of damage so was'nt quite flat allowing oil thru.