Morris Minor Owners Club

I am used to modern cars so this will probably seem a very blonde question.

Is it normal for an old car to have a permanent oil leak? I am assuming not as gaskets should contain the engine oil within the block...

i think it normal for an old engine to leak oil.if you have the engine reconditioned in the future it should not leak.bear in mind that the last morris came off the line in71,so theres bound to be some wear and tear

dalebrignall wrote:bear in mind that the last morris came off the line in71

Last one in England, yes ;)

It's generally a bad sign if they suddenly stop leaking! ;)

The difficult question is 'how much is too much'?
Most Minors wil;l make the occasional drip - if yours leaves a puddle every day it's not a good sign!

It's generally a bad sign if they suddenly stop leaking!

If mine stopped leaking, then she would be out of oil

alex_holden wrote:It's generally a bad sign if they suddenly stop leaking! ;)

I had a modified gearbox cover fitted last year [by JLH] and there is virtually no leakage at all now.

Engine oil leaks are often caused by high internal crankcase pressure. Make sure the breathers are all clear - and one should be connected to the carb or (not so good) the air filter casing - to create a little suction from the crankcase to remove the fumes. Of course if the engine is badly worn on the bores/rings the fumes will overwhelm the breathers. Check - engine hot and idling, remove the oil filler cap - if there is a plume of fume/smoke then it's badly worn, and high oil consumption and leaks will be inevitable.

thread resurection,

my new to me traveller has a rebuilt 1275 marina engine,
it had a bad leak from the engine rear last year, didnt fancy dropping the gearbox on the drive so gave it to a local garage I know who have classics,

they took the gearbox off (type9 5 spd) and mullerd the crankshaft seal adaptor, I bought another they fitted it, said the oil pump wasnt tight,
gave me the car back and no leaks,

not used over winter, took it out a few times over the last few weeks, and its leaking again,

it has been mentioned that a pipe from rockercover to inlet manifold will help by reducing pressure, however the car has a servo, if I T into that pipe will it still work?

bobtail4x4 wrote: ↑Mon Apr 13, 2026 10:21 pm thread resurection,

my new to me traveller has a rebuilt 1275 marina engine,
it had a bad leak from the engine rear last year, didnt fancy dropping the gearbox on the drive so gave it to a local garage I know who have classics,

they took the gearbox off (type9 5 spd) and mullerd the crankshaft seal adaptor, I bought another they fitted it, said the oil pump wasnt tight,
gave me the car back and no leaks,

not used over winter, took it out a few times over the last few weeks, and its leaking again,

it has been mentioned that a pipe from rockercover to inlet manifold will help by reducing pressure, however the car has a servo, if I T into that pipe will it still work?

Your question is about engine breathing. All of the A-series engines have some method of relieving crankcase compression. Even in an engine in excellent condition, there is some "blow-by" of gases from the explosion in the cylinder that gets past the piston rings and can cause a pressure build up in the crankcase. This pressure causes oil leaks and in severe cases, the oil can leak out from multiple places.

The earliest system of engine breathing in the Minor was a pipe from the rocker cover to the air cleaner. Blow-by gases (which contain water vapour) are sucked back into the engine via the air cleaner AND fresh air goes into the engine via a Swan-neck pipe (draught tube) on the tappet chest cover. One or both of these pipes often blocks and the engine then leaks oil.

Later 1098cc Minor engines moved to an oil separator chimney on the tappet chest and a pipe to a PCV valve on the inlet manifold. The very latest Minors had that pipe going to the carburettor (a special SU HS2 with an inlet for a breather pipe).

What breather pipes does your Marina 1275 have? The 1275 engines do not have removable tappet chest covers so there is usually a breather on the timing chain cover. Is that what you have? If so, that pipe would normally go to an inlet on the carburettor I think but I don't have a 1275 so I am not positive on that.

Classic signs of a breather system that is not working properly are oil leaks and mayonnaise inside the rocker cover. The mayonnaise is an emulsion of oil and water from the water vapour not being drawn out.

It sounds like your engine has a modified rear crankshaft oil seal rather than the original scroll (Archimedean screw oil thrower). These oil seals sound like a great idea but in practice they are usually a disaster without proper machining and they often leak.

Stephen

IMHO the lip seal conversion for the 1275cc Marina is a waste of time and money. Unless the flywheel mounting flange outer face has been machined/ground or fitted with a speedy sleeve the seal will fail. The oil pump bolts may have been slack but the oil pump is within a oil tight (or should be) housing sealed with a gasket and held in place by the rear engine plate. The rear engine plates are known to crack between the oil pump cover aperture and the cut out for the rear main bearing cap. Hopefully the rear engine plate was checked for cracking. Make sure that you have the right rear engine plate. 1098cc rear engine plates modified for 1275cc engine use are not suitable as the oil pump centres are different so leading to insufficient metal surrounding and holding the oil pump cover in place. The oil pump covers are also different sizes.
It helps if the engine is turned over on a regular basis to stop the seal picking up or sticking to the flywheel mounting flange if the engine is not used for some time.
As regards crankcase pressure you need to install a separate pipe between the rocker cover/timing chain cover breather and inlet manifold via a pollution control valve (PCV) or the inlet on the carb (use the search facility for more details). Getting the crankcase pressure down on a 'A' Series is most important.
Having the separate pipe will not effect the brake servo.
I did try the lip seal conversion way back and in the end reverted back to the normal reverse scroll arrangement.
Careful rebuilding of the engine meant that I do not have any leaks from the rear of the engine or any other gaskets etc. The gaskets do not need any gasket goo applied to them - lightly greasing both faces of the gasket(s) is all that is required.

My view is that if there is an oil leak, it should be corrected. End of. Most just put up with leaks because either they do not have the skills or can’t be bothered to get it fixed.

as far as I can see there is no vent to the engine, apart from the filler cap,

Marina engine...vent... front timing cover, fuel pump drive ( plate) adapted? .. ?

John ;-)

will have a better look in morning

Below is a Marina/Ital engine with breather/oil separator canister on the timing chain cover:
The mechanical fuel pump aperture can be adapted to mount a breather/oil separator which is then connected to the PCV or carb engine vent intake.
Make sure that the Marina/Ital engine mount bolt holes are sealed - not all of the mounting holes are blind and may be drilled right through to the crankcase. If drilled right through - seal with suitable UNF bolts.

dont recall anything down there, but its under the manifold.
I may just add a vent from rocker cover to air filter,

finally got time to add a vent from rocker cover to air filter,
been out a few times over last few days,
it looks like I have lost about a pint in 40 miles, no trail of oil under car as before,

haw hard is it to swap the rear crankseal to the old scroll type,
I can pull the engine rather than drop the gearbox,
either that or swap the engine/set fire to it, (joke)

The aftermarket crankshaft displaces the crankshaft scroll top half and if it was not retained you will have to find another which is not easy as they are usually specifically machined to suit each block. They are also not easy to get right as regards fit.
Below is what you want

great
Thanks

edit, so it looks like I wont get a seal retainer to fit, (the engine was built for the previous owner) would a speedy sleeve work with the "improved" seal kit?
until this is sorted I cant take the car far to go to any local or national meetings.