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Old 11-18-2002, 09:08 AM
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Join Date: Nov 2002
Posts: 63
95 e320 funny idling sound


I have no experience with W124 104 engine until now. When cold, I notice that the engine makes loud whinning noise. It gets smaller as the engine warms up. Sound occurs around 1000rpm. Is this normal?

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Old 11-18-2002, 10:16 AM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,878
Is it gone when the engine is hot? If it does it then I would suspect the air pump pulley brg. I would not worry too much about it if it is the air pump pulley. If it is there even after the engine is hot it is one of the other pulleys on the front of the engine. May even be the alternator. Pull the belt and use a stethescope to try and determine which one is making the noise. At around 100k miles it may be a good idea to replace the idler pulley and fan clutch pulley.
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Old 11-18-2002, 10:26 AM
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Join Date: Nov 2002
Posts: 63
It's gone after the engine warms up.

I will take a look at the air pump pulley.

Thank you for your help.
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Old 11-18-2002, 12:24 PM
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Join Date: Jan 2002
Posts: 165
As I understand it, this is normal. Should stop after a very short time from a cold start. Ours does it too, the '94 we had briefly did it as well.
1995 MB E320 Wagon
2001 BMW 530i
2007 MINI Cooper S (!)
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Old 11-18-2002, 12:50 PM
Ali Al-Chalabi's Avatar
Senior Member
Join Date: Nov 2000
Location: Knoxville, TN
Posts: 1,837
This condition is probably normal. The whinning that occurs according to engine speed is probably the sound of cold oil rushing through the oil pump, and is normal. The whinning sound not dependant on engine speed after a cold start is the AIR pump.

I remember a post a while back about the oil pump whinning being normal.
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record
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Old 11-18-2002, 12:56 PM
Join Date: Dec 2001
Location: Southern California, U.S.A.
Posts: 8,508
The whinning sound you are hearing is the air injection pump, which runs for about a minute on cold start-up.

This is normal. The pumps are very very loud.

Save your money. The pumps cost over $1,000. Do nothing.
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".
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Old 11-18-2002, 01:11 PM
I told you so!
Join Date: Jun 2002
Location: Motor City, MI
Posts: 2,804
Mine does it too. It's normal. It lasts for 50 seconds or so. I would describe the sound as something between a growl and a whistle. It has to do with warm-up for emissions.
95 E320 Cabriolet, 140K
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Old 11-18-2002, 01:53 PM
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Join Date: Nov 2002
Location: Charleston, SC
Posts: 77
When my '95 E320 that I had bought new was totalled a few months ago, it took me about 2 months to find a identical '95 E320 Special Edition that I bought in Texas and had shipped to me.

When the carrier pulled up in front of my house about 10:00 at night, the driver loosened all the chains, climbed in and started the engine.

Yes!! That familiar whiney/growling sound of the engine on startup.

Don't know what it is but it's normal.
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Old 11-18-2002, 07:06 PM
A. Rosich's Avatar
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Join Date: Nov 1999
Location: San Jose, Costa Rica
Posts: 883
It is definitely normal. My 1995 E320T has done it since new and the dealer tells me is completely normal.

The W140 does it but in a much more subdued way.

A. Rosich
S320, 1998
E320T, 1995
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Old 11-18-2002, 08:06 PM
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Join Date: Sep 2002
Posts: 2,486
If it's a growling noise it's the oil pump. For a short time we were replacing them with "updated" pumps under warranty. The noise was still there but subsided after only a couple of seconds as opposed to a minute or so. It's quite normal( the colder the louder ), and I've never seen one fail, even after 200+ miles. Don't worry about it.
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