strange whining noise

My Sl 500 makes a strange whining noise somewhat loud coming from the angine only at cold start for about 30 seconds or so and it completely disappears after that. only happens in the morning cold start. any ideas?

[Gilly]

I have had this complaint many times from 129 and 140 owners. Usually the power steering gear fluid (power steering fluid) is low. Either that or the belt tightener is getting tired.
Gilly

thanks Gilly for the reply could you elaborate on the belt tightner ? what do you mean by tired ? and what to do to resolve the issue ? do we change it grease it etc ... or just never mind it?
oh and BTW the sound seem to be coming from passenger side so you ruling out alternator huh?

[Smalk]

Hey Gilly-

Could it be the water pump?

[Gilly]

OK, you didn't mention right side. Since it only does it on cold start, and it's on the right, then it may be from the AIR pump, which is a device that pumps air into the exhaust manifold. It's on the right and only runs on cold starts, although I thought it was supposed to run 2 minutes, I could be wrong on that. Whether it's abnormally whiny I don't know, but it is noticeable even it was new.
The belt tightener, by "tired" I mean "worn out". and it would require replacement to repair. Whith the engine off --"duh"---check to see if the belt seems tight or loose, it's a subjective thing, comes with experience.
I would tend to rule out the alternator huh based on it shouldn't be whiny only cold if the bearings were bad.
If the noise just instantly stops, I would say it's the AIR pump and may be nothing to worry about. The AIR pump has a clutch on the front like an A/C compressor clutch. When the engine contol module times it out, it shuts right off.
I cap AIR on AIR pump because it's actually an abbreviaton for air injection reaction pump.
Gilly

[Gilly]

Scott:
I would also tend to disregard that. If it has a definite shut-off time (BANG! it's gone) then I'll stick with AIR pump normal operation. We'll wait and see what the original poster says. The waterpump should be noisy pretty much all the time if it's failing.
Gilly

thanks again gilly the noise doesn't really bothers me as much as it worried me, like I mentioned it's completeley gone when the idle comes(choke off I think) down at cold start, is it a sign of soon failure or anything? anything preventative should be done or just forget about it ? in any event I feel better right now , I'm taking my the next couple of days to have some work done on the suspension I'll have the mechanic also check on this just to get more assurance I'll let you guys know if it was anything strange or different from what you mentioned
thanks and much love to all who replyed

[Gilly]

Please just take special care in reading my second post. What I am saying is that if the noise comes to an abrupt end, after about 2 minutes at idle, it probably is just the AIR pump running, which is normal. There is a possiblity that it is abnormally loud, but i don't know that without listening to it. If it is abnormally loud, then the AIR pump is probably bad.
Gilly

well the mechanic just told me that the sound is perfectly normal yeah baby thanks everybody for the advices I'm picking the car up this evening hopefully the front end is all tight the way I like it to be. I changed the tie rods, wheels bearings, idler arm bushings,center drag link and steering damper, hopefully that should do