belt squeel after jet wash. W124

[tpv01]

took the car to the jet wash last night and stupidly gave it a spray through the grill without thinking and also quickly the underside of car.

I know have belt squeel. It only went after a long drive when engine was hot and weather was warm, although i was in a traffic jam a long time when the belt is not under tension i guess.

it was there again this morning to my annoyance but went quite quickly then came back again as i reversed into a parking space at work!

will it eventually dry out of is there a simple may to tighten it up by adjusting a pulley (OM606 E300d engine with no A/C)? the belt did look a bit slack with it giving a small but notice able ripple when rev'ed slightly from idle.

 

[grober]

What you could be hearing is the alternator under load as it charges the battery- this can lead to a squealing sound when you first start off. Alternatively you could have a belt tensioner problem allowing the belt to squeal under load-it could be wrongly adjusted ,although many are self tensioning - the pulley bearing could be noisy or very worn,-they do wear out after many miles. Or it could be your water pump? You need to take the belt off to check these different components individually for wear. Your poly V belt should not "flap" if its correctly tensioned. if this problem has only occurred since the car wash I suppose you may have got some detergent on the belt which is causing it to slip but this should clear up in the next few days, otherwise its maybe highlighting an existing fault.

 

[tpv01]

alot to go on. yes this noise has only come about since the jet wash. Before that it was as quite as can be. the waterpump was changed very recently so i dont think it is that and presumably the belt would be adjusted to correct tension then.

I am hoping it goes away soon and really suprised it hasnt as it was only the quickest of sprays and i would of thought a heavy rainstorm of driving on a wet road would of let more water through the grill.

what should i check first if it doesnt go away?

 

[Matt45]

I shouldn't worry. I bet that water has got onto the pully wheel and is causing it to slip. What you're hearing is the slipping as the power is overcoming the grip of the belt. Best just let it dry out and I reckon the noise will go away.
I've done the same thing in the past with a number of cars; Jetted the engine and gained a squeel. They go soon enough although I'm surprised that with all this hot dry weather it hasn't gone by now.

 

[tpv01]

They go soon enough although I'm surprised that with all this hot dry weather it hasn't gone by now.

exactly!

when it has cooled down i will go out and have a look at the belt. are there any guide lines about how tight it should be? not being able to twist it through more than 90° is a method i have seen for other cars but not sure it would apply to a long V belt.

 

[Matt45]

I think on Mercs the tension is set up by the belt tensioner to a set tourque but in the old days you could guage it by stretching the longest length no more than half an inch. Does that make sense? take the longest part between 2 pulleys and move it up and down; the max movement should be no more that half an inch at the extreems. I'm sure there are some experts that will give you the proper dimensions, but as I said, I bet it goes away.
By the way, do you leave it out at night? If so any condensation in the air, made worse by the hosing, will linger on the rubber and make the noise in the cold mornings. Try leaving the bonnet open in the sun. Matt

 

[SilverSaloon]

yeah i would say let it dry out. Maybe with the bonnet left up as above to aid it.

 

[Number_Cruncher]

Your belt is tensioned automatically by the spiring that is fixed on the front of the cylinder head. The only things that stop this workiing are;

- the spring is broken!
- the tensioner pivot is siezed up
- the poly v belt has worn badly, and is sitting too low in the puley grooves

There's no adjustment you can make.

 

[Ade B]

there are different sorts of belt tensioner depending on engine and age.

I believe the later cars are simpler and self set up, I think the earlier ones (which I have) are a bit more fiddly.


Ade

 

[tpv01]

ok just been out to check and the belt is very loose. i could quite easily pull it off the the right pulley (power steeering?) surely that is not right!!!

the belt looks in good nick and not stretched. maybe it is the wrong belt (maybe for A/C cars but there is no THAT much slack).

 

[Number_Cruncher]

>>there are different sorts of belt tensioner depending on engine and age.

It's a spring setup, as I described. It's just visible in the piccies posted about the manifold job.

 

[Matt45]

It should be tight so sounds like you may have a problem. All of mine have been so tight you couldn't pull them off.

 

[Uberwagon]

Just get a new standard belt, I had exactly the same symptoms. My tensioner has a small arrow on it and it shows when it hjas run out of adjustment, when this happens the belt loosens and slips.

Dave!

 

[tpv01]

ok just been out there to check again and number cruncher is right it looks like the tensioner assembly.

I saw a mini shock absorber type thing attached to the head and pushed it out/lengthened it and it tightened the belt up. I thought that there must be a spring inside that stretches it out to the correct tension that has broken but coming back in to look at the diagram i found this

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=124131&M=606%2E910&GA=722%2E435&GM=717%2E433&CT=M&cat=19T&SID=20&SGR=045&SGN=03

not sure if i saw the spring marked #107 so that could explain it. Will have to go out again and check it is there or not. a new one is £16 from MB which is pretty pricey for a small spring but i suppose it has to be done. could just use an old bed spring!

 

[Number_Cruncher]

Look very carefully at the spring. The fact that you can move the pivotting tensioner arm by hand suggests that the spring is the problem.

Make sure that it is engaged at both ends - at the top, it fastens into the plastic block, and at the lower end, it hooks into the tensioner.

Also, check that the spring itself isn't broken. As the spring is sheathed with a rubber tube, a break may not be obvious - pull the rubber back and have a look.

The damper is just that, a damper, it doesn't apply any tension to the belt - the spring is responsible for the tensioning force.

 

[Number_Cruncher]

>> not sure if i saw the spring marked #107 so that could explain it.

It was there when you were doing your manifold job! Although, there's nothing to stop it having broken off in the interim.

 

[tpv01]

you must know exactly what you are looking for and have good eyes becasue i cant see it in my pics. Has it got the rubber sheath around it which would explain why i didnt see it?

 

[Number_Cruncher]

It's in the second piccie - the one where the crossover pipe and black plastic cover are off. At the lower edge of the photo, find the top hose. Then, going left, you see the small vac pipe coming up from the vacuum pump. Then, just to the left of that, you can (just!) see the spring & rubber sheath.

 

[tpv01]

you are 100% spot on number cruncher. superb observational skills!

went to look at it again and the spring was missing. looked down and it was lying on the undertray. Dont know how long it had been off but sometime in the last week since the manifold off job. it is a miricale that it didnt fall out of the undertray. seems to be in good working order. will put it back on this afternoon and make sure it is held in securely.

another fixed in a day job thanks to you guys!

 

[tpv01]

actually a couple of further questions while i am on this point:

1/ will anything need to be readjusted if my belt has been slipping off the the pulleys? i am guessing not as it just drives the fan, power steering and stuff but its worth double checking

2/ the famous v-belt tensioner i have heard spoken about must be in this area. where abouts is it exaclty now i am familiar with the spring and damper?