13 replies to this topic

[FZE]

I've had a squeak in my engine bay for a while now, and to put my mind at ease today I removed the serpentine belt and started the engine, it was indeed the source of the noise. I was told by someone that I may be able to apply a conditioning solution to the belt to stop the squeaking, but a little research tells me it could also be either the tensioner or idler pulley making this noise.

How can I determine which is the problem without buying them all one by one? Apparently the only thing to be replaced for the idler pulley is the roller, but on offer are the tensioner pulley and two different (1, 2) tensioner assemblies.

[prasamin]

does it happen at idle, or when accelerating?

you can try conditioner to see if it's the actual belt...if the noise persists, then i'd put money on the tensioner....but always a good idea to replace the pulley, tensioner and belt at the same time.

[ping23]

do you have an ac compressor? compressor could be on its way out and about to seize.

[FZE]

I do have a compressor, I haven't engaged it since Summer 2009 since my condenser got punctured. Can the compressor be left out of the serpentine route or will that put too much slack in the belt?

Oh, and the noise is while idling.

[bergmjs]

Go buy one of these: http://www.harborfre...cope-41966.html

Start the car and start poking things running off the accessory belt.

I thought my squeak was the tensioner before I used the stethoscope, replaced it, still squeaked. Got the scope and found it to be the AC compressor.

[Gilhuly]

Spray some wd40 on the belt while running. If the noise magically disappears the belt simply needs to be replaced. If not then its something else and i would use a mechanics stethoscope or a long screwdriver to try and isolate the sound.

[FZE]

Well, WD40 on the belt made the noise disappear for about 30 seconds, so I'm guessing that's the problem. I'm looking at some replacement belts and apparently there are two different belt routings one can use, and two lengths of belt depending on which? My belt goes in front of the alternator, behind the idler pulley, and in front of the compressor, would I benefit from buying the longer belt and using the "new" routing that places the idler between the PS pump and alternator?

[bergmjs]

Pretty sure if you order the belt for your car it will be the newer one unless you specifically hunt down the old one. The routing was modified by Volvo to get more belt wrap over the alternator, you should probably just buy the new belt.

[Kiss4aFrog]

You've already found the problem but the other thing to do any time you replace a belt or are trying to track down an accessory drive noise is loosen or remove the belt and physically use your hand to feel for play on all the pulleys and idlers and spin anything you can to see if it makes noise. You can have more than one problem and it's a pain when your new belt gets taken out by a bad tensioner, idler, WP or ..... five hundred miles down the road.

[FZE]

I took the tensioner off yesterday and spun it by hand, it does indeed have a sort of rattle to it that I think might be causing another noise, and it appeared to be totally caked in rubber dust. I cleaned off what I could and lubricated it, but it still rattles to an extent, so I'll be replacing it. More worryingly, however, is when I spin the compressor wheel, it gives off an awful slow grinding noise, so I'm afraid it's about to go. I can apparently bypass it with a 49.5" belt, but if I want defrosting this winter that might not be an option. Is there a good compressor replacement write-up?

[Kiss4aFrog]

I don't know about the compressor write up but remember you might be able to get away with just the clutch bearing !! That way you might be able to do it on the car and not even break open the lines. Haven't done one on a 850 so don't know if there's room but it's something to look into to save you a couple hundred. It makes a difference if you're spinning the belt pulley, it rides on the bearing or if you are on the very end clutch plate which is attached solid to the shaft running into the guts of the compressor. The pulley should spin freely but the clutch plate end won't spin but you can turn it to feel any binding or roughness.

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[bergmjs]

FZE, on 21 November 2011 - 02:57 PM, said:

I took the tensioner off yesterday and spun it by hand, it does indeed have a sort of rattle to it that I think might be causing another noise, and it appeared to be totally caked in rubber dust. I cleaned off what I could and lubricated it, but it still rattles to an extent, so I'll be replacing it. More worryingly, however, is when I spin the compressor wheel, it gives off an awful slow grinding noise, so I'm afraid it's about to go. I can apparently bypass it with a 49.5" belt, but if I want defrosting this winter that might not be an option. Is there a good compressor replacement write-up?

Why would the AC compressor affect your defroster?

[Kiss4aFrog]

Almost all cars with AC run the AC system when switched into defrost. First it runs through the heater core to warm the air up and then across the evaporator to pull out moisture so the air is dryer when it hits the windshield. It defrosts quicker and more thoroughly. It's why it's so hard to defog your windshield when it's 85 degrees out and raining if you don't have working AC. The air is so loaded with moisture it can't pick it up off the windshield.

[rocketman4321]

Also remember to check the idler pulley as well as the tensioner. Don't just spin it--put some side load on it with your hand, like the tensioned belt does. Mine spun quietly but felt rough when loaded.