whining nose upon cold start on 300CE
 

There is a noticable whining nose coming from my engine upon cold starting that gradually fades away as car heats up. I thought it might be the smog pump so I ordered a rebuilt one, removed mine and crossed my fingers...bad news, noise is still there. Does anyone have any ideas as to what it might be?

Antonino

Well I would think that you would want to diagnose it rather ask for guesses.
Go buy a 10 dollar automotive stethoscope. Start the car cold. Carefully, avoid all the whirling things, touch the probe to the various front end rotating accessories. You will now when you find it.

Steve

May be the power steering pump. Mine does it when the temperature is below 35*.

It's difficult to quantify "whining", but what you are hearing may be normal. I believe the origin is the belt drive and the whining noise appears to attenuate as things warm up, but is still there to some degree when warm.

Make sure all the bearings are tight by trying to wiggle the pulleys. If they are tight you probably don't have a problem.

Duke

If the car has the M104 engine in it - the noise could be motor oil running through an oil tube that is too small to handle the cold, viscous oil quietly. This has been documented before and it won't cause any damage. I'm not as technical as other members here but I do remember this problem as I hear it all the time in the winter with my '94 M104. It goes away after about 4-5 minutes? What year is your car and how many miles?

Whining noise on 300CE
 

Thanks to all of you who have responded. The car is a 1991 with 148K. I did, as one respondant suggested, listen for the noise with an automotive stethoscope and it seemed like the noise was coming from the smog pump...hence me replacing it. However, as anyone who has done this before realizes that noise does travel and it is hard to pinpoint sometime. The oil line reference makes sense. Is there a solution or do I just live with it? Thanks again for your suggestions.

antonino

One way to check the "smog" pump is to simply remove the belt and start the car to see if the noise is still there. I do not think it would hurt anything, as my car does not even have it connected. I have seen several cars in the past with the things completely removed. :rolleyes:

It is very likely the air pump - they make noise on cold start up. This is normal. You probably replaced a good one with a good one, and the noise remained the same.