I have a 98 E300 turbo diesel.

There was a chirping sound from the engine area. The engine has 199K on it and the belt has 96K on it (ie this is the 2nd belt).

I replaced the belt. The chirping sound was still there.

Last night, going home, when the air conditioner was on, a squeeling noise was coming from the engine. When I turned the air off, the sound went away.

This morning, I started the engine and left the air off. Whenever I reved the engine, the squeeling sound was there.

I would like to get some ideas on how to trouble shoot.

Thanks

Drop the belt on a COLD engine and then run it for 30 seconds. That will tell you if the noise is from one of the accessories the belt drives or if is elsewhere.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Also, how's your power steering fluid level? Those pumps can make some pretty bizarre noises on cars if they are sucking air. Also, once air gets in there, it can sometimes take a while (and some lock-to-lock turning) to bleed the air back out of the system.

Terry's suggestion is better -- start with the belt itself, then move down to checking the accessories like a PS pump. Just don't run for very long without the belt on!

Cheers, John

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'98 E300TD (W210) | Sold 6/09 with 205k and counting
'04 VW Touareg V10TDI

I checked the power steering level several months ago and added a bit a fluid.

Do you have experience taking the idler pulley off (ie the one in the center of all the pulleys)? Does the fan need to come off to take the idler off. I was going to loosen the serpertine and turn the idler to see if it was bad.

I appreciate your advice and will try it.

The key is to remove the belt, see if the noise is gone and if so, check every pulley by hand.

The idler pulley can be removed if the tenison on the belt is released. Is a 10 minute job.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

I was going to short cut it. I will take your advice and remove the belt and see what I get.

Thanks for letting me know that the idler pulley removal is a 10 minute job.

The one item you cant check by hand is the tensioner pivot arm that the tensioner spring and damper shock attach to.

It has no bearings, rather a sacrificial sleeve insert that rides the 17mm hex head pin attached through the pivot arm into the timing chain cover.

The sleeve wears out eventually and can squeak; or wobble and cause vibration at the spring/shock. The easiest way to replace it is to pull the radiator. If you have small hands AND dont mind losing some skin IT IS possible to do so by pulling sheet metal crossmemebr and pulling the rad forward and only removing the shroud and fan itself.

Sounds like you need tto pay special attention to your AC clutch.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Well once I though about this, I had a direction.

The squeeling started when I changed the fan belt. I went down to my MB dealer, paid 20% more for a fan belt and presto, problem went away. The Continental belt I bought from Performance Product 4 Benz was bad. I looked at the belt and it looked fine. For me, the belt will be a part I buy from the dealer.

steve, my 98 mercedes developed a similar problem at just over 100,000 miles. it took me a while to hunt down the culprit, even though I am a above average mechanic. I determined it was my serpentine belt tensioner vibrating, thus making the belt chirp. I ordered a new style tensioner And installed the new style tensioner vibration damper. ( a small stabilus/bilstein shock absorber) my old tensioner didn't have the mount for the damper. the other end of the damper connects near the thormosat housing on my car. i took photos while doing the job if you want to see them. anyway the end result- no more vibration, therefore no more chirping.