w124 engine wine on start up (lasts 30 seconds) then fine

Its probably the charging load on the alternator. It usually pushes out high current for a few seconds after a start to top up the battery. Battery voltage comes back up--- charging current goes down -load on alternator is reduced- sound disappears. Probably a reflection that the battery isn't charged up quite so much on these colder /darker days- nothing to worry about.

 

I'm assuming there is an attachment which I cannot hear on my work computer. With that in mind don't shoot me down for a stupid answer, but have you checked if the starter is disengaging properly. Can stay engaged if solenoid is dodgy or spindle is not lubricated corectly.

 

I guess you could get a friendly vehicle electrician to put a clamp meter on to the ALTERNATOR output wire and watch the current - if the charge current subsides with the noise - you have your answer. It might mean the alternator front bearing is very slightly worn which means you hear it more under load but its nothing to worry about. Other thing to check would be that the alternator is charging adequately- might need a new regulator/brush pack- or your new battery might be duff. Quite few possibilities but really pretty normal behaviour unless it gets worse.

 

It' s the air pump.

 

If its the air pump try this thread:- http://www.mbclub.co.uk/forums/engine/93265-w124-e320-air-pump-pulley-required.html

 

they all make that noise dont they?

 

Mines makes this sometimes but only when i havnt moved the thing for a little while. It then goes away.

This is known to be perfectly normal i am advised.

A few 124's ive heard now make this noise upon start up.

 

Our 280 sounds very similar for a few seconds but not quite as loud as yours. Dont think its anything to worry about

 

Yes they do all make this noise I don't think you have anything to worry about.

When you start the car have a look at the pulley furthest to the left(just above the alternator.) In the centre the nut will spin. When the centre nut stops spinning it will be the exact time the car stops making the noise. This will confirm without doubt it is the air pump.

If it was the alternator why would it stop after 30 or so secs?? Doesn't make sense does it.

 

Charles Morgan will be along soon to ask which vineyard it's from...

 

He'll know which vineyard - he'll want to know which side of the vineyard...

Nick Froome
the independent Mercedes Estate specialists

 

Typical of the M104-24V....the earlier M103-12V sounds much better on start up

 

Air pump, I think.

Mine's been making that noise from when I bought it in 1997 with 135K Kms until today with 370K Kms. I think it's the air pump.

It seems fine after 235K Kms so I'm not worrying. Maybe you shouldn't either.

Bon courage.

RayH

 

Is the air pump you all are refering to is the a/c compressor?
I had similar whine from mine, which stopped, as soon as compressor clutch disengaged. I bet on the a/c compressor.

 

Would this air pump be fitted to a 1996 non CAT E320?

 

see the post 7 link
and what to look for
AIR PUMP INTAKE AND EXHAUST MANIFOLDS

 

Hmm, could someone tell me what's the purpose of the air pump?