Compression drop?

[Slaphead]

I've just noticed that the compression drops continually on my wifes '95 200TE. When the accelerator is pressed all is fine and it drives very well byt as soon as the car stops - or at least the revs stop - the needle drops to zero. On my own E200 the needle stays at teh top all the time once the engine is on at all and and I remember an older 200TE where the needle dipped a bit when the car was at lights or whatever

as I say the car is driving absolutely fine but is this a sign of something nasty about to happen?

 

[maddog]

I've just noticed that the compression drops continually on my wifes '95 200TE. When the accelerator is pressed all is fine and it drives very well byt as soon as the car stops - or at least the revs stop - the needle drops to zero. On my own E200 the needle stays at teh top all the time once the engine is on at all and and I remember an older 200TE where the needle dipped a bit when the car was at lights or whatever

as I say the car is driving absolutely fine but is this a sign of something nasty about to happen?

compression or vacuum???

 

[Bolide]

Compression

I think Slaphead means oil pressure...

I've seen both behaviours: cars where the oil pressure stays pegged at 3 and ones where it drops off at idle. There's probably a bafflingly technical explanation involving oil pump wear, oil pressure relief valve settings, temperature and oil viscosity but I think the short answer is don't worry unless this is a major change from how the car has behaved in the past

Is it due an oil change?


Nick Froome
www.w124.co.uk

 

[Slaphead]

I think Slaphead means oil pressure...

I've seen both behaviours: cars where the oil pressure stays pegged at 3 and ones where it drops off at idle. There's probably a bafflingly technical explanation involving oil pump wear, oil pressure relief valve settings, temperature and oil viscosity but I think the short answer is don't worry unless this is a major change from how the car has behaved in the past

Is it due an oil change?


Nick Froome
www.w124.co.uk

I do indeed mean oil pressure... poor chice of words. I don't think it's due an oil change but, as you say, if there's no differnece in driving then don't woory too much. I'll keep an eye on it though.

 

[gfern]

I had a similar effect on my 300se some years back my friends similar car always was at 3 bar which never dropped below that figure which caused me to ask the same question, my mech told me that as long as it goes back up to 3 bar as soon as you touch the throttle it is Ok, and nothing bad happened in 60,000 miles of driving after. I would worry if it doesn't go back up when using the throttle. I think it says this somewhere in the owners manual as well.

 

[Slaphead]

reassuring! Thanks.