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MG Midget and Sprite Technical - A Series Sump Seals

I have had a leak on the Sprout, the cause was due the amount of times I have had the sump on and off in the last year, and compressed the cork strips, what so you all recommend ?

Do I go with handcut cork for the crankshaft seals, or go TAM 1089/TAM 1171 formed rubber seals ?

Ta.

Malc
Malc Gilliver

I’ve used both and they both work.

Also, ISTR seeing a shaped cork seal in the dim and distant past.
Dave O'Neill 2

Thanks Dave,

I found this - https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=97&subjectar=97&thread=200908160841148415

Some indicated positive points of view for each option, but the thread is old !


Malc Gilliver

The key to fitting cork seals successfully is not to trim them flush with the top of the sump. Leave about 4-5mm protruding each side, so everything is properly under compression as the sump is tightened. Apply a dab of sealant where the gasket meets the main caps but otherwise leave the corks dry.
Paul Walbran

Hi Paul,

I am pretty sure they were not that proud when I fitted them and tbh the sump has been on and off so many times I have probably crushed the cork to death anyway. I have bought seals from the MGOC today and will see how they go.

Thanks for the info though.

I am still happy to return your paint if you can get a return note !

Malc
Malc Gilliver

I had recollections of leaving the seal 1/16" proud, but when I checked the BMC WSM, it wasn't much help at all. (photo 1)

Haynes, on the other hand, does indeed quote 1/16" (photo 2).

I've always trimmed the seals so that the tops are level, rather than angled, as they would naturally be.




Dave O'Neill 2

I found the original cork gaskets did not need any trimming. I have just bolted it all together with a suitable sealant such as Hylomar around the caps.
Bob Beaumont

Bob

Were they straight pieces of cork, or were they shaped?
Dave O'Neill 2

Dave
They were not shaped just slightly oblong pieces. I have checked a spare unipart set and they are the same.
Bob Beaumont

Brown and Gammons due a shaped cork part
Malc Gilliver

Well got the pain in the ar*e back home and while she is running much better, the front crank/sump oil seal is leaking again, this time I went with the rubber shaped seal and it leaks, so I have done some wrong or I am missing something - any ideas ?


Honestly, with the time wasted over the wrong main bearings and lots of other minor niggles I am very close to calling it quits and sending the car to the crusher.
Malc Gilliver

Hi Malc,
I had a leak from the front crank / sump area. Turned out that I need a new pulley as the new oil seals I fitted didn’t make any difference. Tried it twice.

New pulley in and has been bone dry since.

The leak looked like it was come either from the front of the sump or the timing cover. Really hard to tell.

Not sure if that helps you.

Pic shows when I fitted the cork sump gasket. I added a little blue in the corners as well for good measure.

Good luck

James




James Paul

Calm down Malc, we all been there so are with you. A dollar for every time I have threatened mine with matches and I'd be doing nicely. 🤣😂
We had a leak in one of ours once from the bottom of the groove the seal sits in. I suspect that hot tank treatment removed some of what seals between main sump and the add-on that forms the groove.
Paul Walbran

Thanks James,

I was wondering about the pulley !

Thanks Paul,

I hadn't considered that, I will check. I have had the sump powered coated, so hopefully any holes will be gummed up with that.


Next question, can I replace the pulley with the engine in situ ?

Thanks,

Malc
Malc Gilliver

No worries Malc,
You can in a ‘65, but still need to undo the engine mounts and raise it.
My pulley leak the oil drip was sitting right at the bottom of the timing cover, rather than the sump, but wasn’t clear exactly where it was coming from. Took a while to find it was the pulley.
James Paul

Could be the pulley oil seal, or the timing cover gasket, worth checking...
Tim C

Hi Tim,
Yes definitely worth checking both of those first.
Replaced them first twice but made now difference, so ended up changing the pulley.
Believe you can get a speedie sleeve but really not worth if for the price.
James Paul

Hi Tim,

With all the issues this engine as caused me ( all finally traced back to the engine shop supplying std bearing for an ground crank)that I bought sheets of gasket paper, so all new gaskets at each refit, and I used used the crank pulley from my old engine, so I'll be getting new oil seal and pulley, after that I will just give up.

Hi James,

Feels like we are following the same path.

Malc
Malc Gilliver

Malc--did you centre the timing cover up to the crank when it was fitted up---If it's not centre then the seal can leak.
William Revit

Hi Marc,
Let us know how you get on.

Also there’s a guy called Howard on the Facebook group looking to buy the hardtop I sold you. If you’re it using it could help pay for the new pulley. 😉
James Paul

Hi William,

No I didn't centre it - good call !

I plan to get a new pulley - been wanting to that anyway and will get a new seal and then centre it better.

James,

What hardtop ?

I had and Ashley GT hardtop that I sold years ago, but have never bought one.


Malc
Malc Gilliver

Sorry Malc I’m getting you confused with Malc from Worcestershire!
James Paul

This thread was discussed between 01/09/2025 and 24/04/2026

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