sda1030

95 e320 with 115k miles. All services since new, plus many age/mileage related repairs from previous owner. Very gently used in the last 5-10 yrs (about 2-3k miles per yr - less in the past 2 or 3).

Starting cold - sound like model airplane engine comes from the top / cener of the motor. Rises and falls in time with the motor revs. Doesn't ever really go away, just gets less intense as the car warms up. Hear it while driving, and it's making me crazy! I want this car to be a little more "smooth and creamy" sounding. This noise, while not as loud and clack-y as a diesel, reminds of that!

Local, recommended, MB mechanic said it may be injection pump and would not be unsual.

Any thoughts?

Thanks.

ZedStyle

i have the same car, and i hear that noise too. it sounds worse when the car is in my (tiny) garage, but it gets quieter after a bit. i have no idea what it is though...

shdoug

Is it a Diesel? If not, there is no injection pump. Mine always made a noise like a power steering pump that was low on fluid, which is kind of a growl. I guess I am having trouble resolving the similarity of a diesel sound vs. an .049airplane engine. Is it a whirring noise, or a rattly rhythmic sound?

forcedawd

Sounds like the bushing on the shock for the belt tensioner dried up!

There is a bushing in the little shock and when that dries up it vibrates back and forth on the mount causing a clacking sound. One way to test it is start up the car and apply pressure to the side of the shock with a screw driver to see if the sound goes away.

If so, then remove the bolt that goes through the top of the shock and replace with a bushing or washer that you can get at any local hardware store.

Here is an attachment:

Reference page 2 figure 10.

Sam

sda1030

I see in the previous owner's records that the belt tensioner and shock were replaced twice - once in 01 at 89k miles, and again in 04 at 104k. I don't see an item listed for the bushing. Why wouldn't that be replaced as well?

shdoug: The sound is somewhere between a whirring and rattly rhythmic sound. It's not a diesel, and this sound reminds me of the whiny power steering pump on the 1978 Ford Granada my mother had when I was in high school (and beyond). I thought the mechanic said injection pump, but it was 7am and I am sure I misunderstood!

shdoug

It could be the shock/damper. I hear they frequently make noise and need replaced, but somewhere in this forum there is a thread about it (I think the title was "Damn Rattling") and it describes a fix for this. If it's that other noise, I never did figure out where it came from. I assumed it was the power steering pump as it got quieter as it warmed up and never seemed to worsen. It does give the car a Ford-like sound that is somewhat objectionable.

sda1030

I know I'm not really describing this accurately. It's not a rattling sound - that is, it does not sound like somethin loose that is banging against something when the motor vibrates. It's definitely a mechanical whirring sound, and I hear when I'm driving the car as well. Not exactly a "tapping" sound - the closest thing I can compare it to is the model airplane engine.

I'm going to display my ignorance here - could this be feul injector/cam/valve related, do you think? The sound is definitely originating from the top/center of the motor. If I took off the cover, would I be able to see something?

This noise totally ruining my enjoyment of this fine ride, as it completely distracts from the silky "Mercedes-ness". Based on driving other W124s that did not have it, I have a hard time accepting it as normal.

jgajito

I have the same thing on my '94 E320, almost sounds like a turbo whinning...(I wish...)

shdoug

Record it and upload to YouTube. We'll have listen.

sda1030

I've managed to make some technology useful. (It's only how I've made a living for 20 yrs - I should be able to figure something out)

http://www.youtube.com/watch?v=hBK_tpY3ZNA

The video starts right after I the engine starts, just after the buzzer stops sounding. You can hear how loud it is intially, then after about 10 secs it gets lower as the idle slows down to normal. When I step on the gas the noise gets louder as the engine revs up - you can hear as I maintain the engine speed for a few seconds. It might be slightly less obnoxious as the engine warms up more, but it never goes completely away.

shdoug

Sounds just like mine did. I just assumed it was normal for the M104 engine.

How long has yours sounded like this? If it always has, it's probably normal. Maybe it's related to the valve timing mechanism. That is the only thing I can think of that's at the top of the engine where you say it's coming from.

Bigpete123

My car sounds like that as well. Is your car idling at high RPMs at first?

To me, it just sounds like an engine idling at high RPM. I don't hear any rythmic clicking noises so maybe I'm missing something.

Arnie

I have the same noise on the cold engine since I bought the car is 1999. Since then I put amost 100K miles on it, still humms when cold. The best guess I could come up with was power steering pump. There is no noise with the serpantine belt off, which rules out the internal components.