I have returned to the mini scene after a long hiatus. Have had my 1275cc rebuilt and is all running well except for one issue. The engine is freshly rebuilt and done minimal KM. I have oil dripping out of my Gemini starter motor once the engine heats up. There is mnimal play in the primary gear due to new bushes. New clutch oil seal installed (now twice) and getting oil coming out of the starter motor (see picture). After pulling the clutch housing off there is no oil on the clutch plate nor the primary gear. I have no idea where this oil is coming from. Any advice would be appreciated!

PS don't worry about the colour of the oil it's just the camera. It is definitely oil

Is it coming from that hole in the starter motor? How much comes out? When you remove the starter motor is there any evidence of oil entering it?

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Does the starter motor have an oil-able felt washer for a bush? It may have been over-oiled?

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"Show me the Mini!"

It is dripping from that hole yes. It appears oil is being flicked about inside onto the fly wheel and into the starter motor. It is a constant drip once the car heats up. When you remove the starter motor you can see oil on the flywheel. The clutch was pulled apart yesterday to see what was going on but we couldn't find a source of where the oil is entering. There was only oil on the flywheel but nothing on the clutch plate or primary gear. The clutch seal was replaced again for good measure but still we have the problem. I have all the required breathers too. This one has me stumped.

Do you have a flywheel housing breather?
There may be oil dripping into the flywheel housing from the breather and onto the flywheel and being flung around inside the housing.
Just a thought.

Edit: Forget that. I forgot it vents into the gear side of the flywheel housing. Unless the housing is cracked in that area its not likely.
RonR

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68 build Mk1 Cooper S
72 Clubman GT project. Total restoration required

Thanks Ron that is one theory too. I do have a breather there. Would there be much oil coming from the breather?

If there is a hole in the breather to the housing what is the best way to plug this?

Also maybe the oil seal in the flywheel cover/housing isn't centred on the crank properly? If it is eccentric it could allow oil through?

Another point about engine breather...maybe a lot of positive crank case pressure is making it worse. If it's leaking at idle probably not a big factor though.

Sent from my Pixel 2 XL using Tapatalk

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Build thread for Supercharged 1275 1967 Deluxe Resto
Build thread for Mini ute conversion 998cc Turbo

When installing the primary gear seal did you make sure you protected the seal surface? It's very easy to damage.
Does the primary gear case have all it's dowels and bolts/studs in it. Oil could track through.

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

I have the exact same problem, Replaced oil seal twice, stumped to know where it's leaking from.

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

Some primary gear seals have been better than others.
I've been told by a Mini workshop that the black Rover MPI one is best currently.

The only other clutch leak I've had was when the Lucas starter pinion lost a tooth and the ring gear flung it up and it broke into the housing breather boss. Bullseye!
I drove 200km home from Wakefield Park with a 'proper' wet clutch.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks for the feed back everyone. Is it possible for that much oil to come through the breather if there is a small hole?

Sure is. It's directly above the primary gear teeth. Which flings oil at it. There is a baffle below it on some housings but not all.

I had to top the oil up twice on the way home....!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

It’s very likely to be the primary gear seal. If it’s not square or damaged on installation not to mention the poor quality of the seals themselves for the last couple years. Make sure there isnt a groove on the primary gear where the seal runs this is often something missed. Best way to install is to remove the primary gear itself and put the seal on the sealing surface prior to installing. Then press it into the housing using a primary gear seal tool.

Also if the rear bush is scored it can let oil through past the primary gear, this is made worse if the primary gear clearance is quite loose as it turns the gear into a sort of pump as it moves back and forth working the oil out.

TheBoy, primary seals was changed correctly, primary gear was perfect, used a seal tool to instal and gear bushes were fine.

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

probably coming through the primary gear, not through the seal, but working its way through the bushes... I have the same thing after installing new bushes - likely because I don't have enough engine breathers, oil comes out of the dipstick tube too

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did I tell you that I won a trophy?