slow coolant loss - BMW318 - catsdad
I have am 18 month old BMW318 with the latest petrol engine. Despite never using for short journeys I get mayonaisse on the dipstick and in 25000 miles have had to add over a litre of coolant. To me this indicates a head gasket failure? The dealer (who seem thorough and competent) have found no leak despite pressure testing and checking the heater circuit and \"asking BMW if they had any instances like this\". All to no avail. They have also said that the mayonaisse is not unusual in this engine - something I find hard to believe. Anybody care to comment on possible causes of this slow loss and whether the gasket (if thats the problem) is likely to fail suddenly and do I just have to wait until it gets gradually worse and gives more evidence?
slow coolant loss - BMW318 - Sooty Tailpipes
Mayonnaise on the dipstick means water in the oil, and as your water level is going down, that is overwhelming circumstantial evidence of a head gasket failure between the oil and coolant ways.

All you need to be certain, is another clue, like oil in the coolant (you could drain this and check.

What did they mean by pressure check?
This is something as far as I'm aware which involves removing the head, and bolting special plates onto it, and then pressurining it with air in a bath of water to look for bubbles, in which case the head gasket would have been replaced upon reassembly.
slow coolant loss - BMW318 - solara
I had a similar problem with a past car.

Immediate assumption by the garage was the head gasket was gone.
Head gasket was changed, but a week later I had the same symptoms. Garage re-inspected, and found that the core-plugs had corroded. These core-plugs are used to close holes which are inherently made in the moulding process. They sit between the oil in the rocker cover and the water coolant.

When these core-plugs were removed (sitting next to the cam shaft), the oil side looked fine, but the water side was very corroded and pitted. They corrosion had made very small holes through which the water sepeed through at high pressure/temperature.

Funnily enough the same problem happened 2 years down the line. I immediately inspected the core plugs and they had pitted again.I put it down to weak coolant mixture.

Moral of the story...Check you core plugs before you change the gasket. Cheap to replace and far easier job.
slow coolant loss - BMW318 - Dude - {P}
solara. - out of interest did your core plug problems occur with a BMW or another make, as I find it hard to believe that Beem core plugs would corrode through in 2 years.???????
slow coolant loss - BMW318 - Aprilia
*Any* core plug will rot through if there is insufficient corrosion inhibitor in the coolant.

Flatoutinfirth - it does sound like your BMW has a very small blow on the head gasket. With this kind of minor water loss the pressure testing is unlikely to show anything up. A better technique would be to check for combustion gasses in the coolant. After a longish run get the garage to waft their 4-gas analyser probe over the open coolant header tank - if it detects HC then you have HG trouble.
slow coolant loss - BMW318 - solara
No mines was not a BMW. Also I wasn't sure whether the garage had changed all the core plugs or just the one causing the leak.

I would still change the core plugs, as a first attempt. If your still getting mayo, then go for the head gasket.

Note: the corrosion holes were only visible when put up to the light. So you really need to pop the old ones out to examine. Just make sure they pop-out and not IN.
slow coolant loss - BMW318 - Simon
Did I read your post right - you have only lost 1 litre of coolant in 25000 miles? To be honest that doesn't sound bad to me. I know it is only an 18 month old car and theoretically it shouldn't lose any but back in the 'old' days, losing that amount of water over that many miles would be nothing to worry about.
slow coolant loss - BMW318 - rg
Forte Coolant System sealant would probably sort this one out.

As used on weak Citroen matrices/radiators to good effect.

Far better than Radweld, Barrs, etc


slow coolant loss - BMW318 - catsdad
Thanks for suggestions to date. Re Simon's point I wasnt clear, the car's done 25,000 miles but I've put in a litre over the last 8,000 or so - "very nearly an armful" in old money. As its under warranty I dont want to risk additives so I think I'll monitor for a while and, if it continues (as surely it must)to the next service in 6,000 miles I'll ask for more detail of the pressure test and take up the gas suggestion. The coolant is only 18 months old and up to strength (minus 30 protection)so core plug idea looks like an outsider. Thanks again.
slow coolant loss - BMW318 - rg
And don't rule out loss through the cap if this vents to atmosphere rather than to an expansion tank.

I can't recall much about the 3-series cooling systems. Although a 316 remains the only car I have ever spun on a public road...

slow coolant loss - BMW318 - DL
Hold on....1 litre in 250000 miles???????????

Slight mayo on the underside of the oil cap?

Sounds like you have a slightly cool running engine to me....I wouldn't worry about this at all.

On the other hand, if you meant 1 litre to 2500 miles, then I would be concerned.

-- - Pictures say a thousand words.....
slow coolant loss - BMW318 - pete2003
I have a similar problem. My 318 is 2 years old, has done 20,000 miles, and like yours, it has the new petrol valvetronic engine. I checked the dipstick last week, and there is white sludge/mayonaise on it. The oil itself around it (which was changed 2000 miles ago) looks fine, as does the coolant. On the lid where you top up the oil, there is a trace of it too, though not much.

I took it into the BMW dealers. The mechanic advised that it may be due to the previous owner (I only bought the car myself just over a week ago) having used it for many short journies which could have caused a build up of condensation inside the engine. He advised me to drive it for a couple of months myself, to monitor the coolant levels, then come back if it's still there. I also phoned BMW sevice. They suggested I went on a long drive then to go back to the dealer if its still there. I went and did 100 miles on the motorway, but it's still there.

I plan to go back to the dealer in a couple of weeks and ask them to do whatever it takes to fix it. I'm not a mechanic, but I'm sure the white slude will wear the engine prematurely, and it will certainly put off a future buyer if they look at the dipstick (Which I wish I'd done). It's still under BMW warranty, like yours, so I am hoping I am in a good position to get this sorted out without paying anything.

Can anyone offer advice on how far the warranty will cover this. For example could I/we demand a new engine if BMW can't find a way of permanently getting rid of the white sludge? Also, what would happen if the engine packed up after the waranty expires given the fact the white sludge started to appear during the warranty?
slow coolant loss - BMW318 - Aprilia
A little mayo on the underside of the filler cap is not a great worry. What would concern me a lot more is mayo on the dipstick, especially with oil that's only been in there 2000 miles and after a long run too.

Keep a very close eye on the coolant level. If you notice it dropping then take swift action - back to the dealer for further diagnosis.
slow coolant loss - BMW318 - pete2003
Hey, Flatouinfifth -

Have you had any luck sorting out the mayo in oil problem? I now have my 318 booked in to be checked out in a weeks time, and am just wondering what the chance of them fixing it will be?
slow coolant loss - BMW318 - pete2003
I've now been told after a thorough inspection by the BMW garage that the white sludge on my dipstick is caused by nothing more than localised condensation in the dipstick tube, which catches on the bulbous end of the dipstick. This is quite common in this type of engine and requires no attention. In my case, there was no coolant loss whn the system was pressurised, so this seems to be different to your problem.
slow coolant loss - BMW318 - pete2003
Any luck sorting out your BMW engine oil issue? I'm really keen to know what the otcome was because it seems so similar to what's happening with mine.
slow coolant loss - BMW318 - Civic8
I think DL is right nothing to worry about.There isn`t an engine that don`t burn oil and evaporate water around so from what has been said no prob`s

Value my car