Crank seal oil leak (again)…
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
By using this site, you agree to our rules. Please see: Terms of Use
-
- Minor Addict
- Posts: 721
- Joined: Sun Jun 21, 2015 9:41 am
- Location: Glasgow
- MMOC Member: Yes
Crank seal oil leak (again)…
Okay, so they all leak and from what I read the aftermarket seal kits are crap. Question is, how much of a leak is normal and at what point does it become a problem?
Re: Crank seal oil leak (again)…
It’s a problem when the driveway suffers ! I’m starting to wonder if you can get an oil free Minor ! I suppose there must be such an animal. Although I can tolerate the leak on my Minor, I’ve been seriously thinking of making a full length shallow ‘drip tray’ from stainless but getting under to measure accurately is not easy and the points of attachment need thinking about.
-
- Minor Legend
- Posts: 1377
- Joined: Tue Mar 26, 2013 8:20 pm
- Location: Chelmsford, essex
- MMOC Member: No
Re: Crank seal oil leak (again)…
The new engine we fitted a few months ago has the scroll set up and doesen't seem to leak at I've no idea why or how long it will last but it can be done ! (it has got oil in it).
I think it's probably a combination of very little blow by and no wear in the crank bearings, the old engine leaked like a sieve and nothing I could seemed to stem it, I had a rubber backed door matt on the drive under it which worked well.
I think it's probably a combination of very little blow by and no wear in the crank bearings, the old engine leaked like a sieve and nothing I could seemed to stem it, I had a rubber backed door matt on the drive under it which worked well.
-
- Minor Maniac
- Posts: 10879
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Crank seal oil leak (again)…
If you have a oil leak from the scroll seal at the rear of the engine it is time to overhaul the engine.
A engine in good condition will not generate sufficient crankcase pressure to push oil past the scroll and into the bell housing.
The 'A' series needs to have good crankcase ventilation even when in good condition.
The lip seal kit fitted to the rear of the 948cc/1098cc crankshaft/block will only work as it should if the flywheel mount flange outer circumference is smooth/machined or a speedy sleeve is fitted. The ex factory machining is not sufficiently good/smooth enough to accommodate a lip seal contact face and that is why most lip seals fail.
A engine in good condition will not generate sufficient crankcase pressure to push oil past the scroll and into the bell housing.
The 'A' series needs to have good crankcase ventilation even when in good condition.
The lip seal kit fitted to the rear of the 948cc/1098cc crankshaft/block will only work as it should if the flywheel mount flange outer circumference is smooth/machined or a speedy sleeve is fitted. The ex factory machining is not sufficiently good/smooth enough to accommodate a lip seal contact face and that is why most lip seals fail.
-
- Minor Legend
- Posts: 1670
- Joined: Thu May 12, 2016 6:33 am
- MMOC Member: No
Re: Crank seal oil leak (again)…
I would disagree with that, if there is nowhere for the, even minimal, piston blow-by to be vented from the engine (even the dipstick hole might not be enough). ‘Likely’ might be a better way of suggesting an overhaul is necessary.philthehill wrote: ↑Thu May 05, 2022 7:37 am If you have a oil leak from the scroll seal at the rear of the engine it is time to overhaul the engine.
A engine in good condition will not generate sufficient crankcase pressure to push oil past the scroll and into the bell housing and finally out past the jiggle pin.
Or do you think the front crankshaft oil seal should leak first? My 7 1/4 litre engine was losing oil via the rear seal (admittedly only a cork seal) until I replaced the totally clogged/rusted mesh in the crankcase breather pipe. It doesn’t ‘breathe’ a lot, but the total breather blockage had to result in the blow-by going somewhere else!
-
- Minor Maniac
- Posts: 10879
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Crank seal oil leak (again)…
If you read the post in its overall context it says that the 'A' Series requires good crankcase ventilation.
If you have good crankcase ventilation and oil is getting past the rear scroll then it is obvious to me at least that the engine is worn and requires overhaul. There should be no oil getting past the rear crankshaft scroll.
Regarding the word likely in the context to the rear scroll - the engine either requires overhaul (leaking oil) or it does not (scroll doing its job and no leak).
What I will say however is - how much oil the owner is prepared to accept getting past the scroll will determine the time line for engine overhaul.
As regards the front pulley seal - again good crankcase ventilation is essential but a leaking front seal is caused more by wear to the seal and/or surface wear to the pulley shaft.
If you have good crankcase ventilation and oil is getting past the rear scroll then it is obvious to me at least that the engine is worn and requires overhaul. There should be no oil getting past the rear crankshaft scroll.
Regarding the word likely in the context to the rear scroll - the engine either requires overhaul (leaking oil) or it does not (scroll doing its job and no leak).
What I will say however is - how much oil the owner is prepared to accept getting past the scroll will determine the time line for engine overhaul.
As regards the front pulley seal - again good crankcase ventilation is essential but a leaking front seal is caused more by wear to the seal and/or surface wear to the pulley shaft.
-
- Minor Addict
- Posts: 721
- Joined: Sun Jun 21, 2015 9:41 am
- Location: Glasgow
- MMOC Member: Yes
Re: Crank seal oil leak (again)…
Thanks for the replies. My engine was rebuilt 18,000 miles ago. It seems sensible to investigate its ability to breathe. The breather pipe runs from the rocker cover to the air filter?
For context here’s what my car leaks overnight. Would be useful to know if this is what others consider to be ‘normal’.
For context here’s what my car leaks overnight. Would be useful to know if this is what others consider to be ‘normal’.
- Attachments
-
- 2B909878-25A1-472A-B67F-CE06B16E720D.jpeg (380.64 KiB) Viewed 1606 times
-
- Minor Fan
- Posts: 473
- Joined: Thu May 11, 2017 8:23 pm
- Location: South Cheshire
- MMOC Member: Yes
Re: Crank seal oil leak (again)…
I get a single drop every week but I have fitted a hif 38 carb which has a vacuum pipe fitted to a crankcase breather oil trap.
-
- Minor Maniac
- Posts: 10879
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Crank seal oil leak (again)…
Morris John
That oil leak is not normal.
A well built 'A' Series does not leak oil.
Phil
That oil leak is not normal.
A well built 'A' Series does not leak oil.
Phil
Re: Crank seal oil leak (again)…
If it leaks that overnight, quite possible it is not the crank seal -it is quite a lot...
-
- Minor Legend
- Posts: 1670
- Joined: Thu May 12, 2016 6:33 am
- MMOC Member: No
Re: Crank seal oil leak (again)…
I think I actually simply quoted your post (in entirety) for my pot. That might indicate that your post was ‘adulterated’/modified some time after I made my post.philthehill wrote: ↑Thu May 05, 2022 8:08 am If you read the post in its overall context it says that the 'A' Series requires good crankcase ventilation.
If you have good crankcase ventilation and oil is getting past the rear scroll then it is obvious to me at least that the engine is worn and requires overhaul. There should be no oil getting past the rear crankshaft scroll.
Regarding the word likely in the context to the rear scroll - the engine either requires overhaul (leaking oil) or it does not (scroll doing its job and no leak).
What I will say however is - how much oil the owner is prepared to accept getting past the scroll will determine the time line for engine overhaul.
As regards the front pulley seal - again good crankcase ventilation is essential but a leaking front seal is caused more by wear to the seal and/or surface wear to the pulley shaft.
Re: Crank seal oil leak (again)…
Oh goodness , takes me back 50 odd years to the school playground. Wish I could add my two penneth worth but don't know anything on this subject. Is it normally this competitive ?
Re: Crank seal oil leak (again)…
On a positive note, the escaped oil does look nice and golden. My drips are black
Re: Crank seal oil leak (again)…
On a positive note, when I got my car it leaked oil like the Torrey Canyon. Followed advice and sorted out the crankcase breathing which was blocked. Now I hardly get any leaks at all, perhaps a spot every now and again and that’s likely to be mostly residual
-
- Minor Fan
- Posts: 254
- Joined: Tue Oct 26, 2010 9:01 pm
- MMOC Member: No
Re: Crank seal oil leak (again)…
I would suggest looking at the breathers before any drastic work. My Traveller was dripping a lot of oil until I checked the breather outlet on the rocker cover. It was completely bunged up and took a lot of cleaning to free the gunk. Now she is as oil tight as she can be.
1969 Traveller in Almond green. Owned since 1979.
-
- Minor Legend
- Posts: 1377
- Joined: Tue Mar 26, 2013 8:20 pm
- Location: Chelmsford, essex
- MMOC Member: No
Re: Crank seal oil leak (again)…
Is there somewhere a definitive description of what each breather system should consist of ?
I am aware there is the gauze filled can can on the tappet cover going to the air cleaner and pipe to the ground from the tappet cover type crankcase breather, but there are also valve covers with and without breather pipes and If I understand correctly vented and non vented filler caps as well, can someone advise which should go with which?
I am aware there is the gauze filled can can on the tappet cover going to the air cleaner and pipe to the ground from the tappet cover type crankcase breather, but there are also valve covers with and without breather pipes and If I understand correctly vented and non vented filler caps as well, can someone advise which should go with which?
-
- Minor Maniac
- Posts: 10879
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Crank seal oil leak (again)…
With the 803cc, the 948cc & 1098cc engines the rear cam follower cover do not have a vent.
The 803cc. the 948cc and 1098cc engines front cam follower cover can have a open breather pipe to below the block. There are at least two different styles of open pipe.
The front cam follower covers fitted to later engines can have the oil separator canister which can be connected to the air cleaner or the PCV valve or the carb.
The front cam follower covers with the oil separator have the sealed breathing system i.e. the rocker cover does not have a breather but it does have a vented oil filler cap.
See link for additional details:-
https://www.moss-europe.co.uk/shop-by-m ... 51-71.html
The 803cc. the 948cc and 1098cc engines front cam follower cover can have a open breather pipe to below the block. There are at least two different styles of open pipe.
The front cam follower covers fitted to later engines can have the oil separator canister which can be connected to the air cleaner or the PCV valve or the carb.
The front cam follower covers with the oil separator have the sealed breathing system i.e. the rocker cover does not have a breather but it does have a vented oil filler cap.
See link for additional details:-
https://www.moss-europe.co.uk/shop-by-m ... 51-71.html
-
- Minor Legend
- Posts: 1377
- Joined: Tue Mar 26, 2013 8:20 pm
- Location: Chelmsford, essex
- MMOC Member: No
Re: Crank seal oil leak (again)…
Great thanks, I 'm going away to work out how to add the equvalent of a breather cap to the alloy cover on our 1098!