mayonnaise in the cam cover

[ericbushby]

Hi everyone, I need some advice.
Recently I have noticed some small drops of water on the top of the footwell under the carburettors.
Also the water level dropping in the radiator.
When recently testing something else on a cold morning with the garage door open, I had large clouds of white smoke, filling the road outside. This was obviously steam from the exhaust.
When I removed the cam cover it was coated completely in white emulsion (mayonnaise).
Also in the rear of the airbox near the vent pipe from the engine.
So, I thought, that is probably a head gasket failure, although it is not something I have had before on any car.
I took the head off, but I cannot see any obvious cause. The block surface is good, the gasket shows no evidence of failure or places where it has leaked and the head surface looked OK but not good.
Three piston tops were clean and number 4 had a sooty deposit on it which scraped off.
Sorry, no photos.

The local cylinder head repair specialist who also runs an Elan, agreed it had probably not failed, but criticised some pitting too near the bore. This has now been welded and it is due to be skimmed soon.

So, the next thing is, if it is not the gasket where should I be looking next.
My experience is limited, but I have had the head off before to replace a broken valve spring and adjust shims. I have also had the engine out to find an oil flow problem and another time to work on the clutch.

I am looking for suggestions please from more experienced people as to where to go from here.
Looking forward to your comments and suggestions.
Eric in Burnley
1967 S3SE DHC

[elanfan1]

I’m probably the worst mechanic on this forum but thinking logically water has to be getting into your oil from the coolant somewhere. My thoughts are maybe a corroded waterway in the head?

[HCA]

Interesting one, a water jacket corroding inside the head, and I guess possible...if this is the case, then I think the oil in the crancase would also be milky.

Common problem on Minis. If there is mayo in the rocker cover and the head gasket and oil in the crankcase are definitely A1OK, there are two general possibilies - you live in a high humidity area and/or are doing too many short runs that does not give the water vapour time to evaporate - instead the vapour from each short run collects in the rocker cover. The other possibility is you are in a high humidity area and using too thick oil.

[elans3]

+1 to the above. If your runs are normally short ones, then that could well be the cause of your problem. I also used to see it on Mini Coopers in my youth, particularly in Winter, when I never stayed out for long. Under normal circumstances in Winter, your exhaust will chuck out lots of steam after a few seconds, which is only the heat burning off the condensation in your exhaust. It should then stop after less than a minute, depending on how much was in there.
The only other causes would be head gasket (or excessive pitting around a water passage or combustion chamber), crack in the cylinder head, crack in a bore .
The only other cause of white smoke out of the exhaust would be failure of the servo, allowing brake fluid to be sucked into the combustion chamber & burnt off. (obviously that doesn't give you mayo in the cam cover).

[ericbushby]

Steve and HCA, Thankyou for your suggestions.
I certainly live in a high humidity area here on the edge of the Pennines but this is something new. I have never lost water level in the radiator in the 10 years I have had this car. Yes Steve, 10 years. ( Steve is a previous owner, two owners back.)
I never do short runs and the engine reaches normal running temperature every time it`s out.
The oil is nine months old, 20/50 semi synthetic, not milky, just discoloured. It has done only 700 miles and would have been due for changing in May when I normally do the annual service and safety checks. The low mileage is due to Covid virus restrictions, no club meetings, no shows, no mates and nowhere to go. My daily driver Ford did only 3 miles in April and May.
Thanks
Eric in Burnley
This post overlaps the one above,

[alanr]

Thoughts...
To state the obvious if you have steam coming out of the exhaust there is obviously water getting into the combustion chamber somewhere/somehow.
You say you are having some welding done on the head and I presume skimmed back to true.You will of course need to check how much, if any, has previously been taken off the head from standard thickness before it is skimmed! I do hope you have someone who understands the Twink head doing the work on it?
The twin cam cylinder head was a very crude casting even when new compared to a modern cylinder head so it doesn't take much to turn it into a pile of scrap. Luckily new heads are available from QED but at a jawdropping price!
If it were me I would have wanted the cylinder head crack/pressure tested prior to any welding being done on it. There could be internal porosity or a crack somewhere internally in the head.

You would have to be very unlucky to have crack in the block I think although having the block surface skimmed very slightly, again taking the bare mimimum off, if you have the engine stripped wouldn't go amiss.

Alan

[elan_fan]

It was a cold day here in Telford and i was idling my diesel astra while i tried to free off a frozen caliper behind the car was a cloud of condensation to make a steam engine feel at home. The engine (though high mileage) is perfect- totally normal

Do you move your car outside much to let it idle etc as it is not being used. If so then while its cold like this you will easily get a build up. Either run until you lose oil pressure when idling (oil is hot) or leave it unstarted in the garage. Many people change the oil just before they stop for winter and then you have nice clean (uncontaminated) oil in the system while hibernating.

Do you have a recuperating bottle on the rad and do you refill and by how much.

Do you have a summer stat in and big radiator, great for summer and bad in winter.

If you have been running with water in the combustion, the offending area will be steam cleaned- nice clean piston and half cleaned valves and a cleaned plug

Shutting the door after the horse etc i know because the engine is in bits,
But with older cars, they often have “problems” which are just normal operation for our antiques

Best regards
Mark

[ericbushby]

Thanks Alan,
All suggestions welcome. The welding is just to fill in a small area of pitting so that a light skim will produce a better finish than without. It must have been skimmed before as there is evidence of previous welding.
The head thickness now before the skim is 4.640".
Two people have put doubt on the water pump. I do not know if a failure in the pump assembly can cause a water leak into the engine. The pump spins freely with no end float and barely perceptible rocking. Similar to what you get with a road wheel nut backed off to the next castellation to fit the split pin.
If that was the case, I wonder if that would let water into the sump and contaminate the oil first which so far I have not seen.
I am a little out of my experience zone here and am listening to any suggestions carefully.
Thanks
Eric

[alanr]

Eric,
I think the water pump theory whilst being a long shot possibilty could happen if there was a crack in the innner casting/plate but is unlikely. If you did have water going into the sump mixing with oil the oil would look like condensed milk on the dipstick which I am guessing that you don't have?
My bet is on the cylinder head or gasket being the problem...Either the head being porous, hence my suggestion to have it crack/pressure tested, or slightly out of true and although you said you couldn't see anything looking at the gasket, sometimes it is hard to see any slight water tracking that may have taken place.

Alan.

[ericbushby]

Hi Mark and thankyou for being interested enough to make suggestions .
I use the Elan all year round provided it is not raining and no salt on the road. It is not `put away` until spring. I never leave it idling to warm it up so I would not know how big a cloud of steam it can make.
An 83 degree thermostat is fitted and working correctly. The temperature gauge normally reads around 75 in winter and 90 on a hot summer day. The accuracy of the gauge is not bad.
That day, I did have it idling an unusually long time on a cold morning while I was checking something else, and the condensation cloud was alarming. Maybe I over reacted on that. But, at the time it explained why I had been losing water from the radiator and the recuperation bottle, with drops of water appearing under the airbox. which I have not seen before. There is no gasket on the airbox cover.
Thanks
Eric

[ericbushby]

Hi Alan, I overlapped again.
Unfortunately I know nothing about the water pump and how it can fail.
However I thought the same, that the oil in the sump would go milky first and it has not done.
I will discuss testing the head with the machine shop, I believe they can do that.
If it is the gasket failing as I assumed at first, then I am on to a winner. It was just that I could not see a fault and neither could the machine shop guy who is familiar with cylinder heads.
Of course in that case I will know only after rebuilding it, hence my questions.
Cheers
Eric

[Donels]

The mayonnaise is a classic sign of water in the oil, BUT not necessarily from a leaking gasket. I once had an MG Maestro that was well known for creating mayonnaise in the cam cover. This was due to a long breather pipe at the front of the engine allowing condensation to form. Austin Rovers answer was to add lagging to the pipe.

When the head is rebuilt you could get a 'sniff' test carried out of radiator. This looks for hydrocarbon evidence in the cooling water indicating exhaust gases getting into the cooling water, but should also indicate oil getting into the water.

[Fred Talmadge]

I had water in my VW Beetle. I wasn't driving much, just a short 2 mile drive to the train station, barely enough time to warm up. Condensation was the cause. A decent long drive fixed that problem.

[LaikaTheDog]

I once had an A series engine crack its head behind a valve, so it all looked perfect until I pulled out the valves to decoke and grind before putting it back together... Then ended up needing a new head.

[Andy8421]

Thoughts...
To state the obvious if you have steam coming out of the exhaust there is obviously water getting into the combustion chamber somewhere/somehow.

Alan

Petrol is a hydrocarbon, and produces water (among other things) when you burn it. I couldn't find a definitive answer, but for every gallon of fuel you burn, over a gallon of water is produced. 15% of the exhaust gas is water vapour.

Given this, it is no surprise that a car produces clouds of white water vapour on a cold day. Until the engine warms up, this water will condense wherever combustion products find their way - most obviously the exhaust. I have often followed a car producing a stream of water out the exhaust pipe when it pulls away. Inside the engine, any ring blow-by will lead to water vapour condensing inside the engine until it warms up enough to dry out - so 'mayonnaise' can be a symptom of excessive blow-by, an engine with inadequate venting or not run long enough on each journey to warm up and dry out.

Having said all that, if Eric's car is now losing water, and didn't produce 'mayonnaise' before, then something must have changed. A combustion chamber to waterway leak can lead to bubbles of combustion products in the waterway during the power stroke, and water being squirted into the combustion chamber during the intake stroke which would explain the water loss, but this doesn't automatically mean that the water will find its way into the oil to produce 'mayonnaise'. A minor water leak into the oil may explain the problem, but a major leak would result in the oil forming a milky emulsion with the water - which hasn't happened.

Not much help now, but a pressure test on the cooling system would have helped diagnose the problem. Given all the above, my best guess would be a minor leak from the water system into the oil - either via a head gasket or water pump, but it could easily be a combination of other factors - sorry I couldn't be more useful.

Good luck.

Andy.