Zed82

This started the other day when i took the car out for a spin. It happened approx. 4-5 minutes after a cold start and i didnīt drive it hard or anything.

It sounds like a high pitch fan noise coming from the driver side, around the front lights. It sounds as though something is going to break or burn up.

I tried to disconnect the main engine fan but the sound was still there. After trying to locate it i drove the car a couple of blocks and the sound became lower and the suddenly it was gone!?

Also, today i noticed that the whine on the upstart is a little more high pitch then usual. When the car is warm, everything is perfect. This doesnīt affect the performance at all.

What could it be? Itīs an E55 2004.

Zed82

I should add that the sound was still there even when i shut the engine off.

moosejaw

the E Class is infamous for this
Jet Engine Fan is common in these cars and proof that it works.
It only makes this noise when idling right or slow speeds?

Should calm down once car is going.

Zed82

Shouldnīt the engine fan stop once i disconnected it by pulling out the big connector on the left side of the fan?

This sounds more high pitched and i never heard it before.

Iīve driven this car HARD this summer with many miles in hot weather and 200 mph races on the german autobahn. Never had the sound before.

Bramage

There is nothing that spins with the engine off. I was going to say alternator bearing, but again, that would not continue after the engine is turned off. My old Audi would run the fan after you turned it off, but the E55's dont do that, and also: You disconnected your fan.

I'm stumped.

When I get a tough mystery to solve like this, I drive my car harder.. That usually helps uncover the problem

E55Greasemonkey

Sounds like your air (injection) pump is running all the time, likely the relay is burnt/stuck closed.

Zed82

If the relay was stuck and burnt, the pump should be on all the time? The noise selfcancelled after 5 minutes.

How many fans are there in the car? Could it be the oil cooler fan? Cause this really sounds like a little fan on max rev. Like a high pitched vacuum cleaner.

211.070

The oil cooler is on the passenger side. Your airmatic pump, and secondary air injection pump are on the driver's side.

Zed82

Then it has to be the air injection pump. What happens if it fails and is it expensive/hard to fix it?

taurran

I was told there's a catalytic converter heater motor that runs up there, and will make a loud whirring noise. At least that's what an experienced MB mechanic told me my car was doing. It usually only happens on cold starts, lasts a few minutes, and then stops. I want to just disconnect the damn thing.

Zed82

It sounds just like this. A jet engine noise.