mayonnaise in oil filler neck..

[leo316]

Hi folks l hope someone can help here with there experience and also people who have had the car l have..
l have a X Reg A140, and today l had the bonnet up to check the oil and water.
l took the oil cap off first and notice at the base of the neck that it was full of mayonnaise and was thinking of head gasket straight away so l checked the water and the expansion tank was still full with no signs of oil in it.
l then looked at the dip stick and this was fine no signs of mayonnaise in there or traces of water in the oil.. The oil level was between min and max .
The car runs perfect with no spluttering or missing and has no problems with accleration..
So why the mayonnaise . l have read somewhere that these cars are prone for mayonnaise build up at the base of the oil filler neck and in the dipstick sometimes and could be a oil breather problem'' Is this right ?

 

[Carrsey]

If it is a fairly small amount this can be caused at this time of year if you only do short runs so the car is realy getting up to full temp..

 

[WG M-B]

The 168 petrol engines dont breath the best! and as most are used for short journeys a bit of mayo is commonplace in the filler neck. As long as the oil is in good condition and you have no other underlying issues its best to not worry

 

[leo316]

The 168 petrol engines dont breath the best! and as most are used for short journeys a bit of mayo is commonplace in the filler neck. As long as the oil is in good condition and you have no other underlying issues its best to not worry

No chaps there was alot at the base where the pipe bends.. but no other signs elsewhere.. the dipstick had none and was just black oil... The car seems fine and l don't think it overheats as nothing shows on the dashboard. The fan kicks in so l have'nt had the car long so can someone tell me where these cars show the temperature ...
Also is there a oil breather pipe on these engines that may be blocked that l could clean out..

 

[grumpyoldgit]

Common problem in cold weather with condensation. (As emited from the exhaust in cold weather). As has been said, it's normally caused by short journeys and the engine not getting up to full operating temperature. What does the temperature gauge read when it's warmed up? It should be above 80ºC.
If the breather hoses are easily accessible you could take them off and clean them.

And/or you could give it a good run.

I've had the same thing with cars in the past, not only MB's.

 

[leo316]

Not being funny here but l don't know where to check for the temperature as there's nothing to see on the dashboard, like l have said l've only just had the car..so any help here would be really helpful..

 

[Howard]

There is no temperature display on the w168 A class.

Have a look at the site linked below , it is the A class owners bible , helped me out no end with ours.

Albert Rowe, Lofty's homepage

If the oil is good , the cooling system isn't being pressurised and you aren't losing coolant , i wouldn't worry.

Welcome to the forum by the way.

 

[leo316]

Thanks for the help folks..

 

[area51]

It might be worth thinking about the thermostat, if the engine is not getting properly hot (mine wasn't) then this might make the situation with mayo in the filler neck worse?

Obviously there is no temperature gauge, does the top radiator hose get so hot that you are unable to keep your hand on it? If the top hose is only luke warm then a new thermostat is the order of the day. An added bonus is the speed with which the engine/heater gets up to temperature (toasty).

 

[markjay]

As others said... 'mayo' under the oil filler cap is a sign of engine running cold, a few good motorway blasts will cure it.

As you said there may be an underlying issue such as faulty thermostat - or low-quality oil (some oils are more likely to 'froth' than others) - but essentially this by itself is not an indication of blown head gasket.

Other blown HG symptoms are 'mayo' on dipstick, oily deposits in the coolant, loss of coolant, presence of exhaust gasses in the expansion bottle, cooling system loosing pressure, water in exhaust when engine is not cold, one or more cylinders not firing.

 

[BlackC55]

The mayo in the cap is very normal on that car.

It's not because the car is running cold either. The oil filler neck is very long so moisture condensates at its highest point.

Don't worry and ignore it.