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MG Midget and Sprite Technical - Oil leak

Hi
The help I have been given so far on this forum has been excellent a bit of it over my head but getting there
So next problem is an oil leak from the rear of the engine between it and the box I have read a few different pieces on it and think it may be to do with the canister on the timing chain cover so question is how do I open the canister
I believe the engine should have vacuum in the engine and should be able to breath but I think the canister is preventing it
Hope this makes sense
Cheers
Russell



R Deans

The leak from the rear meain bearing is a common problem on A series in line engines. There is a scoll on the crankshaft that is meant to throw the oil back into the sump but its not always effective. The archives list a number of ways of trying to solve or reduce the problem so worth a look.

In answer to your question,the Canister is a sealed unit so you can't really open it. Inside the canister there is a quantity of coarse wire wool which can become clogged. To clean it you have to really remove it from the engine. Try washing it out thouroughly with engine cleaner or similar. If that doesn't work then the wire can be replaced but its a fiddly business (You can use those stainless steel wire scourers as replacement).

Are you sure there is a vacuum? the canister should be connected either by a pipe and Y piece to the SU carbs or on earlier engines to a PCV valve on top of the inlet manifold.
Bob Beaumont

i think what is happening is the canister is blocked and a build up of pressure is forcing oil out The engine has just been rebuilt but I am not sure what condition the timing cover was in or whether the canister has been cleaned there is nothing coming out of it
So i think a clean out would be first thing to do
R Deans

How many miles on the engine, it might take a few hundred or more for the rings to be fully bedded in before the blow by drops to a normal level.
David Billington

it has only done about 30 miles
R Deans

Russell,

With that few miles on a new engine I wouldn't bother chasing oil leaks out of places like the scroll seal, you need to get some more miles on it and see how things settle down when the rings bed in. No harm in checking for a blocked breather can but the PCV system isn't going to cope until the rings are sealing properly.
David Billington

I can see from the two questions I have asked and the answers I am getting that there is a complicated beast and I thought I was going back to simpler times
The engine was bought along with the car
It has been rebuilt with a fast road cam in it big valve head and who knows what else
It has a Weber 45 DCOE carb fitted and does not have the PCV system in place
The person I bought it from has no more info on it
I have spoken to the original owner who reshelled the car his info was very helpful but not with the engine it’s not the original one
As said I have only done 30 miles in the car but so far apart from the rev counter and oil leak the engine is running really well
So this weekend I will try a different coil to see if it affects the rev counter
Try and unblock the canister on the timing cover
And any other sneaky faults that pop up
Russell
R Deans

Hi Russell,

Without a working PCV, even when the rings are well bedded in, you'll still have enough pressure in the sump to blow oil past the rear scroll.

If the timing chain cover oil sepatator is also blocked, that'll make it worse. But even if free to 'breathe' through there, you'll still need additional means to reduce sump pressure.

Plus. The PCV isn't only there to reduce sump pressure to prevent oil leaks. It's to keep the oil as 'clean' as possible, by venting out water vapour, and the piston blowby combustion products that contaminate the oil.

With a webber, you don't have a low and constant 'vaccum' connection point to make to the timing cover oil sepatator.

Hence you'll have to employ the original 'mushroom valve' type pcv valve, that connects to the inlet manifold. Or use a pcv valve from a different car.

Or, you'll at least, have to add additional free breating ports to vent the sump.



anamnesis

anamnesis
Great answer
That’s sort of what I thought
I will put it on my to do list or ask what other Weber users have done
R Deans

I have owned the 1971 midget since new. The dealer changed the timing cover seal at least twice and the harmonic balancer to little avail. The car always leaked at the rear of the engine since there is no seal. Once, parked on a hill after a very hot and hard run, a couple of quarts of oil syphoned through the scroll onto the parking lot.

I later adapted a seal kit (Rivergate) and this reduced the oil leakage at the rear almost completely. The timing cover leaks have also improved with seal quality.

I recommend venting the timing cover to the intake manifold using either the original diaphragm PCV valve or a small Toyota/Mazda PCV valve. I am using one of these on the B with a downdraft Weber and there is almost no oil consumption at all.

I have metal drip pans beneath both the Midget and the B on the garage floor. I recently rebuilt the Midget engine and have no noticeable leaks for the first time since I have owned the car. We'll see just how long THAT lasts!
Glenn Mallory

This thread was discussed between 03/08/2023 and 04/08/2023

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