Oil-well?

[mechanix]

What sort of oil consumption is normal for an A-Series engine? Mine uses about a pint every 500 miles, this seems quite a lot.

It sometimes emits blue smoke when standing in traffic while warm. I've tried the engine braking down hills and accelerating advice but there was no smoke. Any ideas what could be wrong with it? It doesn't leak that much either...

[Cam]

Ideally none, but virually ALL A-Series engines are a little leaky.

I have an oil leak at the front of mine (due to either wrong sump, or dodgy gaskets, or bent front plate), and it uses about a pint every 500 ish miles. But I am aware of it and a leak is not that much of a problem (even if it is a little embassasing).

If yours is burning oil when you labour the engine, then it is usually piston ring failure (worn). Have a look at your spark plugs and see if they are oily. If they are then that's what it probably is. More likely on high mileage (80k+) engines.

If you get a puff of smoke on startup then it is usually valve stem oil seals. Not too bad a job to change, but it involves taking the head off.

If your problem is piston rings, then if there are no scores in the bore, you MIGHT get away with fitting new rings and honing the bore (can be done with engine in situ - but easier if you take it out!).

If it has done a lot of miles, then it's probably best to rebuild it and fit all new seals, bearings, etc. while you are at it.

[Kevin]

Cam I have been told in the past that it is possible to change the valve stem oil seals without taking the head off.
This is done by first removing the plugs and then making sure one of the pistons is at the botom of its stoke you then feed into the bore some rope when full bring the piston up and apparently the rope will push the valve up thus enabling the collets to be removed without the need for a spring compressor, I have not tried it personally, has Willlie or anyone else ever heard of this old garage dodge, or better actually seen it done.

[Cam]

Kevin,

Yes, I have heard of this before, but I don't fancy the idea of having bits of rope (or any other foreign bodies) in the bores, which could get down the gap between the piston and the bore and cause problems.

Maybe paranoia but I would much rather remove the head than take the risk.

[Willie]

Lo, it was quite common when the Minors and Minis were new to
hear complaints that new cars were using a pint of oil in 500 miles.
The reply was always that "this is within specification"!! and usually
it was said that the consumption would improve as the engine
bedded in. Sometimes it did sometimes it didn't. Have you any oil
dripping from the clutch housing? (where the split pin is visible).
It is a lousy design of rear crankshaft oil seal (Archimedes screw)
which, commonly nowadays, leaks even on 'factory rebuilt' engines.

[mechanix]

Thanks guys,
I'll have a look at the plugs and the clutch housing this evening. The engine is gold, I've been told that means it is a goldseal replacement engine (is that right?), but it looks like it's got a few miles under it's belt.

The odd thing is that it doesn't smoke under power, or when I followed Willies advice about going down the long hill and then accelerating away at the bottom. In fact I've only ever noticed it smoke when warm and idling in traffic. Could this perhaps be to do with low oil pressure? Do engines leak very much more when being used than when left over night? It only leaves a few drips of oil on the ground over night.

The car came with a spare engine which I could re-condition.

[mechanix]

Thanks guys,
I'll have a look at the plugs and the clutch housing this evening. The engine is gold, I've been told that means it is a goldseal replacement engine (is that right?), but it looks like it's got a few miles under it's belt.

The odd thing is that it doesn't smoke under power, or when I followed Willies advice about going down the long hill and then accelerating away at the bottom. In fact I've only ever noticed it smoke when warm and idling in traffic. Could this perhaps be to do with low oil pressure? Do engines leak very much more when being used than when left over night? It only leaves a few drips of oil on the ground over night.

The car came with a spare engine which I could re-condition.

[Cam]

Yes, the chance is that it is a goldseal engine if it is gold.

Could this perhaps be to do with low oil pressure?

For it to smoke at all, oil is getting into the cylinders. I can't see how low oil pressure would make this worse.

Maybe the smoke at idle is due to worn valve guides / stem seals? at higher RPM perhaps the oil does not have chance to make it's way down the valves? just a guess, but a possibility.

Do engines leak very much more when being used than when left over night?

The crankcase is pressurised when the engine is running, so the seals will be more pressurised and leak more. It's more noticable when the car has been sat for a while as the sprayed oil collects, runs down the engine and drips off.

[Willie]

Just a thought....is your engine a very late 1098cc by any chance.
If so does it have a mushroom shaped engine breather fitting on top
of, and in the middle of, the Inlet manifold. These are not too common on the Minor but are a source of potential trouble???????????

[les]

Cam, surely a pressurised oil-seal grips a shaft more tightly when pressurised due to its design, and the need to fit the right way round (concave side to the pressure) but maybe the above post was referring to seals other than the rubber ones (as fitted to the timing chain cover) which could leak under pressure.

[Cam]

Les,

Yes, it was mainly aimed at the gaskets, but I used the term seals to cover both gaskets and rubber seals, as on high mileage engines (which is probably the case here) the crank oil seal can wear / perish and cause leakage due to pressurisation and an imperfect seal.

But you are dead right with regard to a new seal.

Incidently, I had a brand new crank oil seal fitted to a Mini which started leaking oil at an alarming rate after only about 12 months, so it just goes to show that new items are not always perfect!!

[les]

I guess your referring to the 'red' seal ! Happy days!

[Cam]

Yes! well, sort of orangey. Must have been quite common then!

[les]

At the risk of turning this into a Mini forum this 'red' well ok orangey or even brownishy! seal was a must to change if renewing a clutch as any leak there could prove detrimental. It could be installed without removing the flywheel housing if the primary gear was slid off the crank first but a lot of problems were caused by not being fitted squarely. How did we/I get here, anyway this moggy-------

[rayofleamington]

Do engines leak very much more when being used than when left over night?

YES!
1) Generally when they are worn, dynamic seals leak will more when there is movement.
2) Crankcase pressure will increase gasket leakage.
3) Oil flow around the engine (eg. into the rocker box) will put oil in more places and increase the likelyhood of leakage
4) Last but by no means least, hot oil is thinner and will leak at a much higher rate than cold oil.

If there is no smoke after engine braking that 'normally' rules out valve guides, but it's not always easy to see! Try doing it downhill with someone following you, then . At traffic lights a cloud builds up around you and it can be hard to miss, but at higher speed it would have to be really bad before you see it in the rear view mirror.
Otherwise it may be the bores / rings..

On the subject of goldseal engines I've heard no end of bad reports, and somone once told me that these were often new engines that were faulty, so didn't get fitted to cars and were then 'fixed' and painted Gold - but 'fixed' did not always mean they had found or repaired the actual fault.

Maybe that was a rumour, but it's not good when you hear of somone having 3 Goldseal engines fitted, and each one had to be replaced immediately, until in despair the garage rebuilt the original engine.

[mechanix]

Wow, thanks for all your responses!
The car is a 1958 1000 so I would have thought it is 948cc but as it's a different engine it's not necessarily the same capacity. I tried to find out by looking at the engine no. and referring to a Minor hand-book but I'm still not sure. The breather is not the mushroom type (though I'll have another check, Willie).

My question about the oil-pressure was following something along the lines of what Les proposed, but I don't really know that much about engine oil seals so I thought I'd ask. The reason I was examining oil-pressure was that I only notice smoke while hot in traffic. (Less viscous oil, slow pump)

I got someone to follow me and they said it was all ok, apart from a few times when I changed gear. Has that exposed the cause? If it is the valve seals, are they easy to replace once the head is off? I wouldn't be surprised if I did miss it while going down hill, but I certainly don't at the lights. It's getting a bit of an embarrassment!

[Kevin]

Do a compression test on all four cylinders and compare the readings they should be fairly even (cant remember exactly 150 lbs rings a bell) if one or more is reading low, then repeat after putting a drop of oil in each bore in turn and leave for a minute and repeat the test if the reading goes up its the piston rings (+ could be valves as well but if its pistons the lot needs checking) if not its the valves, unfortunatly sound a bit like an oil control ring going past its sell by date I hope Im wrong

[Willie]

Lo, re the engine numbers. If it is a 1098cc the number starts
with 10MA, if it is a 948cc it starts with either APJM or 9M.

[paulg]

When our Minor uses oil (right now in fact!), it is either because:
1) it leaks (tappet covers - mess underneath manifold, rocker cover gasket - mess all around top of engine, blocked breathers - hard to do as they are quite big bore but mess everywhere). I have been lucky as other leaks seem to pass us by!
2) worn rings or valve stems.
It is pretty easy to spot the leaks. Fixing can be harder if the tappet covers or rocker box have been over tightened - easy to do but hard to straighten out - new or good second hand is really the only way.
As to rings or valve wear the tests suggested above are good but if compression is low, then try a test I found on the web - it uses compressed air. It was very useful!
Basically you modify an old plug to take an air fitting, take off the high tension leads and replace one plug at a time with the modified plug. With that piston on compression you pump air into the cylinder. You can hear where the leak is (if any):
exhust pipe - worn exhaust valve seat
carb - worm inlet valve
breathers - worn rings
all of them - serious rebuild!

[Cam]

Good idea that, but be careful of the pressure if you have a massive compressor!!

The worn rings is the only major rebuilding problem.

for the others, just swap or fix the head (much less of a problem).