96 E300 belts chirp/squeak. Replaced everything. Still chirps.
 

I've tried everything.
new belt and tensioner pulley.
I used a parts store belt and that screeched like hell.
So I bought the contitech belt.
That stopped the screech.
After a few days it developed a chirp.
This chirp is present at start, idle and throttle. It only stops after the car has been running for about 30 minutes.... sometimes.

So I put some belt dressing on it.
That stopped the chirp for a few minutes.
I stopped the car let it sit a minute.
When I started it up.
The screech was back worse than before.
So I sprayed more on and let it run as the instructions on the bottle say.
I pressed down on the engine damper there and no difference
I added some tension by pulling the tensioner pivot arm (top of tensioner spring) a little bit and no difference.
The belt feels tight.

Looking through old reciepts I replaced the damper a few years back.. less than 15,000 miles ago.

What am I missing?

Chris, remove the drive belt and check the condition of the fan clutch bearing bracket. I suspect it may have excess play due to worn/failing ball bearings. You can buy a reconditioned fan clutch bearing bracket at your local MB dealer, but need to turn in the old one to avoid paying the core charge.

I agree with fan clutch pulley.. my 94 has play in the fan clutch pulley. It chirps / squeals until warm

The fan is off the car right now. Still squeaking.

I was just about to click "PAY" and buy a new URO fan clutch, but figured I would try a little penetrating oil on the bearing first.
When I had it off I decided to see if the chirp stopped with it off and it is still there.

Is this the part you are talking about?
Fan Clutch 6032000022 - Uro Parts - Mercedes-Benz - 603-200-00-22 | Pelican Parts

What size alternator do you have? I would install an overrunning alternator pulley.

I'm thinking I will go buy a new belt and this time strip the paint off the belt tensioner pulley.
Is that crazy?

Yes.

When you remove the belt, can you spin every pulley by hand freely? Is your belt tensioner spring stretched beyond spec?

Also, when you buy a belt, make sure it the belt length corresponds to the size if your water pump pulley. There are 2 different sizes.

This information also applies to the OM606.
http://www.peachparts.com/shopforum/...3.970-belt.png

http://www.peachparts.com/shopforum/...olant-pump.png

The longer belt length is 2145mm.

Pulley PNs:
#6032050110, 138mm diameter
#6032050210, 157mm diameter

If you have the small pulley get the short belt, if you have the large pulley get the long belt.

"When you remove the belt, can you spin every pulley by hand freely? Is your belt tensioner spring stretched beyond spec?"

I don't know, but the tensioner spring is what came on the car when I bought it.

As far as the belt...



My alternator is a valeo. ( I found that out after I ordered the bosch voltage regulator)

I just found the receipt for the belt and pulley that was on there from 2014 from pelican parts (did not squak for a few years). had I known that I would not have replaced the pulley, trying to think if I threw the pulley out or not... .
Sales slip (pelican parts) says 6k x 2140 010-997-79-92
The one I have on the car says 6PK 2140

I looked online and they are the same as far as I can tell.

I measure the cooling pump pulley and it is 157 MM.

It sounds like I have the correct belt.

I cleaned the gunk out of the pulley grooves before installing the new one. Would that make a difference?

I had a similar situation recently. Replaced everything in the belt tensioning system - belt, shock, spring, tensioner arm, tensioner pulley, etc. - didn't fix the problem. Belt chirp & squeal that only happened when car was first started and first few minutes of driving, but went away once engine was warmed up. Here's my thread: http://www.peachparts.com/shopforum/diesel-discussion/386613-606-crank-pulley.html See post #6 from Murkybenz, he was right on the money.

The problem on my car was the water pump. Water pump bearings had gone bad, causing drag on the pulley and squeals and chirps from the belt. When I replaced the water pump, I found it was the almost twenty year old original from 1998. As soon as I replaced the water pump, the noise was completely gone!

I'm fixing to be there with my 98 E300 at 198k miles. Mine squeaks/squeals once it hits about 2800 rpm.

Belt dressing won't help, ever. It is too sticky at first then drys to a hard slick finish.

The source of flat belt noise is the back of belt is sliding front to back across the flat pulleys making the chirp. ( not a slipping in rotation problem )

First, clean all of the dressing off the pulleys, this will be difficult and time consuming.

Sand the flat pulleys in a cross hatch pattern with 80 grit paper leaving them slightly rough. Paint isn't an issue as bare steel can be noisy as well.

Lightly sand the label on the belt, just take off the slick shiny surface, no need to remove the numbers. This is the source of a cyclic chirp.

The goal is for the pulley to grip the belt rather than letting is slide front to back across the surface.

As stated above, never use belt dressing.

Chris.

Not sure if you did this or not. I just thought that I would mention it.

When changing the idle arm pulley. I believe that one is supposed to add grease if I am not mistaken.

Regards.


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ok. I'm gonna try to clean the pulleys cross sand the tensioner pulley before I go replacing the water pump. Can I clean the pulleys with brake cleaner? carb cleaner is less corrosive.


There is a hole in the top of the water pump housing.
Can I add a drop or two of 2-1 oil?

I did not grease the tensioner puller. I guess I should do that.

Is the water pump a big job? I already have the fan off and fan shroud off.

Water pump replacement is real ez with fan/fan clutch off. Turn the water pump shaft and see how it "feels". Any roughness, hard to turn?

That is the weep hole. Coolant will come out of it when the water pump seal does not work anymore.

Most any solvent will work. Brake clean is generally softer than carb cleaner, mineral spirits will work too.

Not really, the seal has a rubber bellows that will be deteriorated by the oil. This rubber bellows is what usually fails when a water pump starts to leak.

Have a look at my post 3 and 4 http://www.peachparts.com/shopforum/vintage-mercedes/372819-4-5-water-pump-durability.html

In the old days, 50's and prior, some water pumps had a grease fitting or oil cup for the bearings but not the seal.

I'll pull the belt, rotate all the pulleys to see if they go smooth.
Clean the belt, clean the pulleys, cross sand the tensioner pulley. Grease the tensioner pulley shaft, and take the gloss off the back side of the belt.

get back to you later.

While you're in there, I would take a close look at the belt tensioner spring. They do occasionally fail or over stretch.

Since this is a serpentine belt setup, grab your various pulleys and tensioners and see if there is any "slop" in the shafts. If there is, it can cause the pulley to be very slightly out of alignment when the belt is tensioned. The result is usually squealing or chirping. Tight/stiff pulleys due to failing bearings are another frequent cause of squeals on a serpentine setup, you're looking for something that's causing drag.

How do I tell if its stretched.

I will post a pic.

the belt does sit a little close to the outside edge of the tensioner pulley.
I'll take a pic and post.


I think I got that pulley just off the shelf at local parts place(commercial place not pep boys).
If I can find the old pulley should I put it back on? I bought that one from Pelican in January 2014?

Honestly. this might have been my only initial problem..

OK. First off. The belt on the tension sits positioned toward the front of the pulley. It actually extends over the edge by the width of less than a penny.
But it looks like it did that on the original pulley which I found and it shows a grease line where the belt sat. .
Here is a picture. The first two are the Flennor one installed. The third picture is the one I replaced, bought from pelican parts in jan 2014 shows how belt sat on that.
http://www.peachparts.com/shopforum/...?dl=1508518369

http://www.peachparts.com/shopforum/...?dl=1508518254

http://www.peachparts.com/shopforum/...?dl=1508518369

Here is a pic of my spring on a measuring tape. It is MB original. Is it correct length? Roughly 8 1/4 inches
http://www.peachparts.com/shopforum/...?dl=1508518254

Can should I space the tensioner pulley outward to cover that 1/8 of an inch overhang
 

Can should I space the tensioner pulley outward to cover that 1/8 of an inch overhang?

OK. I pulled the new Fenner tensioner pulley and compared to the INA one I took off a few months back.
they are the exact same thickness. The new one spins more freely. The old one spins a few times when I roll it. the New one 4 or five times.
I think I'm gonna go with the new one unless someone has a better idea.

There is no slop in any of the pulleys. they all spin freely but the engine pulley.
the alternator makes a very slight squeak, but spins freely other wise.
The water pump pulley made a slight scraping noise that sounded like it was from where the pulley contact the pump. I cleaned that off and gave it a squirt of oil. (NOT IN THE HOLE) and the scraping sound went away. It turns a revolution of two when I spin it.

A good bearing on a pulley will NOT freewheel. It should feel smooth and "creamy" and make no noise, but if spun, should stop pretty well immediately. If it keeps on coasting, the bearing is toast. Something like an alternator that has some mass to it is another story, but a tensioner pulley should NOT freewheel.

Chris, the link in your Post #4 is for the fan clutch, not the fan clutch bearing bracket to which the fan clutch attaches. By the way never buy any URO parts because they are Chinese junk. Grab the fan clutch and check for excess play or wobble in the fan clutch bearing bracket.

There is no play anywhere. Not on the fan clutch pulley. Nothing really freewheels.
The two tensioner pulleys are about the same. The one that was in there no spins the same as the one I took off a month ago.
I washed the belt and cleaned all the pulleys as best I can with a little of this and that and finished off with a wire brush and carb cleaner.
I think I done good.
Moment of truth.

Well now I'm not sure which pulley to use...

the Pulley on there turns about 1/2 turn when I spin it. (Fenner from the parts store)
The one I took off that is from 2014 Turns like a quarter turn when I spin it. (INA from Pelican parts.)
Both look pretty good.

I guess I'll try it with the one I just cleaned and put back on and if it chirps I'll swap them out.

INA is probably a more reputable brand. If it has a smooth feeling to it, I'd reuse it. It never squeaked with it installed right?

It squeaked with it installed, but the car had been sitting for a year and a few months at that point.

I'll put it on.

I cleaned it and scuffed it.

This is not on a Benz, but this worked for me on the AC belt of a Nissan Hardbody which are notoriously picky with V belts. All belts were new and tension was good. What you're going to read seems counter intuitive, but it if you're going to change the belt anyway, which is where I was, you've got nothing to lose.

I saw a video on the YouTubes where a guy said to spray the belt with 303.

https://www.youtube.com/watch?v=_8RE8p_m8bA

I couldn't find my bottle of 303, so I used Mother's VLR which is similar and smells the same with more cleaning ability. Squirted a good bit on all sides of the belt with the motor running and the AC off. When I turned on the AC it was improved considerably, but would squawk for about half second when the compressor kicked on. The following day, DEAD SILENT. This lasted for about a month until I noticed a little chirping at idle. Sprayed some more product on it and it quieted down again.

OK. What's this fan clutch bearing?

I put it together and it didn't screech.

I put the fan on it started to screech.

I took the fan off and it still screeched.

My car does not have a fan clutch bearing bracket. There is no such part listed for a diesel.
There is for an E320.
Just not for a diesel.

The pulley behind the fan is connected to the water pump.

I tried the water test and it is the belt.
Stops for a few seconds with water.

Ugh.. New belt again.

I've got a new water pump coming:).

Fingers crossed that I don't need one. :undecided


Got the fan back on. Drove for half an hour and now we are back to a pleasant chirp. I'll live with the dang chirp.

When water spray makes it quiet, that isn't a water pump issue.

The pulleys might need cleaned again. Did the label get lightly sanded?

Chris, I read your Post#27 again and it's not normal for the water pump to make a scraping sound when you turn the pulley. How old is the water pump? It's possible the water pump is starting to fail and needs replacement. If so, best to buy a remanufactured one from your local MB dealer. Turn in the old one to avoid paying the core charge.

Water pumps will have a slightly dragging, rubbery feel due to seal friction.