W124 - Oily film under bonnet

[eyelight]

1994 E280, 129,000 miles.
Have owned this car 3 months, once or twice have notice a slight trace of oil under the bonnet, along the area in front of the radiator, between the headlights. Was working on the car on Saturday, and cleaned it up, but after a trip into London and back yesterday, it was there again.

This car had the viscous fan replaced under warranty right after we bought it, but it still runs a bit hotter than our E220, when in heavy traffic like yesterday. Trying to get over Kew Bridge was hell, both directions. When stuck in traffic like that the oil pressure guage was dropping down to about 2 1/3 while in gear, and going back to 3 if I put it in neutral. Normal enough, but I noticed that after a a good while inching along in traffic, the needle would not make it all the way back to 3 when I shifted to neutral. Could thiss pressure drop be related to the oil reside under the bonnet?

The oil filler cap seems to me to be not as tight fitting as it should be. Would there be some kind of negative air pressure under the bonnet while driving that might draw oil out from there?

First step is a new oil filler cap. Any other ideas?

 

[television]

It almost sound like a breather pipe off, does the car smell oily when driving

 

[eyelight]

Thanks for the quick reply Malcolm,
Can't seem to find any breather pipe off, but will give it another look. No oily smell, although I thought I caught a slight burning oil smell yesterday as I pulled up outside the house. I've a notoriously bad sense of smell though, but no one else comented on it anyway.

 

[television]

In this last week we have had 3 cars where the oil cooler for the gear box has been leaking at the front, just a thought, It night be an idea to get a aerosol of engine cleaner and wash off the front of the engine, rinsing off with a kettle of water so as not to get it in the electrics, it makes it easier to see where it is coming from, the fans blow the stuff every where

 

[eyelight]

Thanks Malcolm,

Bought a new oil filler cap from Mercedes dealer yesterday (about £4), so will see how things are with that fitted.

 

[wireman]

Possible front pulley oil seal failiure, but i would expect some oil on the inner wings as well if it is

 

[eric242340]

Check your engine oil leve and check your transmission oil level first.

 

[eyelight]

Thanks all for the replies. I replaced oil filler cap, but haven't been driving car all week so yesterday was first time I could check. Seemed like the oliy residue was much reduced. Will check inner wings when I get a chance, probably tomorrow.

Meanwhile, the return of an overheating problem, means I've got to go try the famous carrot test in the morning as well. Hot day today and stuck in a queue of traffic the temperature inched up and up till the ASR light came on, and the car went into "limp home" mode. Worrying stuff, but beyond the subject of this thread.