Running Engine With Oil Cap Off - What To Expect?

[SJHE]

Just looking for a bit of advice really...

I have a 2009 204 Series 220 CDI and I've just taken the oil cap off while the engine was idling as I remember hearing in the past that this is a good was of judging an engines health. I was surprised/concerned with the results which were akin to a steam train puffing away under my bonnet!

Is this normal?!

The engine has done 90k miles and has a full Mercedes history. It runs perfectly and has only done about 150 miles since an oil change (oil is still mostly golden coloured). I've inspected the PCV valve which is in nice clean condition. I should add that there are no oil deposits etc in the air filter housing.

Any help or advice appreciated, thanks!

 

[mioba]

Sounds fine to me pal

 

[Taffy7hfa]

Normal.

 

[Mr Greedy]

If the oil is still golden, it sounds great and I wouldn't worry. When I have an oil change on my diesel, 1 minute after starting it's as black as soot.

 

[Jim2]

Drive on, no problem.

 

[mioba]

Drive on, no problem.

with the oil cap back on

 

[EmilysDad]

with the oil cap back on

As if anyone would leave the cap off ....

 

[Jim2]

with the oil cap back on

Yes, Mioba, of course...and I imagine that thats what the poster normally does, but he got a bit if a shock when he saw what happens when the engine was running with the cap off, and thought that it was problematic. I changed the oil and filter on the Wifes superb a few days ago. and removed the filler cap to allow the engine to breathe while the oil was draining, and of course to refill it. Afterwards, I ran it ( still with the cap off ) and of course , it forced a little oil out. Quick clean up, and all was well,

 

[mioba]

was a tongue n cheek comment folks

 

[EmilysDad]

was a tongue n cheek comment folks

I replied as I did because I have done ...... twice

 

[mioba]

Hahahah Gotcha.
Well the first time I ever serviced a car (N reg volvo about 25 years ago). I was baffled when after refilling the oil, nothing was showing on the dipstick. Not a drop. I only never replaced the sump nut. Lucky the oil catch pan (a big old cooking pot) was still in place.
Partner was fuming as she needed to go out and it was a sunday. So I had to wait till the next day to get more oil.

 

[SJHE]

Thanks chaps, appreciate the comments!! Was concerned for a second that the piston rings were shot and it was all blow by as the puffing was quite alarming.