Engine rear seal leak

[Rocketman1955]

My 223 has developed an oil leak at the back of the engine.
Obvious suspect is rear crank seal. However this has delevoped really quickly.
I am curious as just prior I changed the engine oil & filter - now that could just be a coincidence.....
The car has been really oil tight for the 2000 miles I have had it, but within 100 miles gone from clean to full blown puddle on garage floor after driving!
As I only do low mileages & annual oil changes I decided to use Halfords classic 20/50 oil to keep costs down and a Bosch 501735027 filter.
Other than the leak from the back end the engine is oil tight & running well.
Oil pressure is about 60psi running & 25psi at idle.
Any ideas on why the seal should fail so quickly - nomally they weep first & create some warning drips?!!
Anywhere else it might come from? - oil certainly being spun off the flywheel!

[howardjs]

Is it definitely engine oil and not gearbox oil? If engine oil, perhaps engine crankcase pressure too high? Oil filler/breather not working/blocked... maybe ..

[Jack602]

I don't recognise that oil filter part number, have you still got the old filter to swop back on to try, in case oil is not flowing through the new filter?

Jack

Pembleton SuperSport

[Rocketman1955]

I do not have the old filter, the new one 501735027 came from Euro car parts.
Subsequently I checked on an oil filter website & they say Bosch 5004927 for all 2CV type applications.
Euro car parts say the 2 filters are interchangable.
The id on the new Bosch filter body is 0451103139 - is it the correct one?
Some sites say P3139 is correct, which is the last 4 digits on my Bosch filter.

I did check the reed valve, although I have not disturbed it other than to fill the engine, it all looks ok.
The breather on my car is vented, but shows no evidence of any discharge.
The rest of the engine still appears oil tight.

It is definitley engine oil as it is slightly discoloured black, and the gear box oil is new & would still be clean.
Also it is the front of the flywheel that is throwing the oil.

The oil level on the dipstick is halfway between max and min and I have checked the dipstick is fully inserted so the engine should not be over full.

My current theory is that maybe the rear seal was marginal and any slight increase in oil pressure by using 20/50 instead of 10/40 was eough to cause it to leak?

I feel an engine removal might be necessary to investigate - at least it easy access!!!

[kawlomax223]

You can’t really check if the reed valve in the oil filler is working by looking. You need to use a manometer. If it’s been there for a long time chances are it could have failed and crank case pressure is too high. Best option is a ‘foo foo’ in my opinion. I would ALWAYS use a Purflux oil filter with the internal check valve and never scrimp on oil. It has a hard life. Just my thoughts. Good luck with a fix.

[notsmartcar]

the seal is pressed in from the out side it doesn’t hold back high oil pressure. If it was high crank case pressure it would throw the oil out of the cam shaft/points box area as there is no seal there... all the rear crank seals if original are well past their retirement age ... mind you I did have my own crankcase crack near the oil filter and only leaked at high temperatures and that took some finding

[Rocketman1955]

Finally got around to fitting new rear crankshaft oil seal - now road tested and all appears ok.
I hired seal extractor and insertion tools from 2cvtools which made changing the seal almost a non-event. It was no surprise that the old seal leaked as when I tried to hook it out it just went further into the crankcase!
Interestingly there is no shoulder to push the new seal against, but the insertion tool just sets the seal at the correct location in the crankcase.

As previous comment above, the seal is not exposed to oil pressure, behind it is an annular cavity with a drain hole in the bottom.

One problem I had was mating the engine back to the gearbox. Despite using the correct clutch centring tool and the original clutch the gearbox shaft would not go into the clutch splines - it was quite tight even if the clutch disc alone was offerred up to the shaft.
Issue was finally resolved by filing small lead in on the clutch splines - it then went together straight away!

Also checked the crankcase vent system with a water manometer, idle vacuum was about 28cm (280mm) , no issues there versus the 50mm minimum spec.

So the oil leak appearing just after oil & filter change must have been a coincidence.

Anyway, job done now, just in time for winter.........