Hi there, I've been experiencing a screeching noise from the front of the vehicle (1984 240 GL Estate) over the last few months. I've replaced the two matched alternator/water-pump belts and the power steering belt with zero change in the situation. I deglazed the pulleys and checked tension and adjusted alignment with zero effect. The noise has been gradually getting a little louder and more prolonged as time has gone on and I've been too busy to look into it further.

I've just changed both front engine mounts as I discovered they had sheared off whilst doing an oil change - the oil filter was a lot harder to undo than normal and then I realised it was sitting on the buggered mount! Anyway, I thought that finally doing this bit of work to the car would have made a difference but the sound is still there and I'm completely at a loss to know what's going on. The noise is there from start-up and comes and goes intermittently at low speeds and disappears completely at highway speeds, it doesn't seem to relate to cornering or clutch in/out but definitely does to revs/road speed, anyone care to put me out of my misery? (and please don't tell me my power steering pump is knackered....)
Without hearing its difficult but would pay to check can belt tensioner those can sieze and make plenty of noise
A cat is stuck under there somewhere.
Get some soapy water and spritz the belts with it while the engine is running. If the noise disappears, you know it's belt related.

Next check the harmonic balancer. You'll need to use whiteout or something to mark the outer edge and centre of it, either side of the rubber bushing. If the marks move relative to one another, it's dead.

Next check the accessories. Disconnect them one at a time (by removing their belts) and see if the noise persists.

If you STILL can't find the source, it's probably the crank bearings.
Garth;97191 wroteWithout hearing its difficult but would pay to check can belt tensioner those can sieze and make plenty of noise
The car's due for a timing belt change so I guess that can be investigated once the cover's pulled off, I've already got the belt (genuine Volvo) and the seals etc as it's leaking oil like crazy but haven't bought the tensioner as yet, maybe I should just buy one and anticipate changing it whilst I'm in there...

jamesinc;97193 wroteGet some soapy water and spritz the belts with it while the engine is running. If the noise disappears, you know it's belt related.

Next check the harmonic balancer. You'll need to use whiteout or something to mark the outer edge and centre of it, either side of the rubber bushing. If the marks move relative to one another, it's dead.

Next check the accessories. Disconnect them one at a time (by removing their belts) and see if the noise persists.

If you STILL can't find the source, it's probably the crank bearings.
Thanks for the detailed response, I've had the alternator reconditioned only a couple of months back hoping that replacing the bearings might get rid of the problems (it was failing anyway) but again zilch at the time. I'm going to follow your trouble-shooting regimen and see what happens, just on the spritzing I had read about this on Youtube already but have only seen it with straight H2O, I was guessing that the water made the belt grab and thereby eliminate the issue, but am wondering if the soap would lubricate the pulley and cause it to slip?
Just had a quick look around online and read that Volvo only fitted harmonic balancers to 85' and onwards, mine's an 84' but I suppose I can get a torch tomorrow and see externally whether it's fully cast or with the rubber?
@Porkchop yeah actually, plain water would be fine. I don't know why I said soapy, I think because you use soapy water for finding boost leaks. Just grab a bottle of water and pour some on the belts while the motor's running, if it's the belts it'll stop squealing near instantly.

You're right, 1984 is probably a B23 motor and therefore no harmonic balancer.
At least that's one thing probably eliminated! :)
Could be power steering pump bracket bushes have failed/worn and kicked the pump out of alignment.
Hi Ash and thanks for the comments, I replaced all accessory bushings with poly a year or so ago and have checked alignment across pulley faces etc but no cigar! I've just done an 'isolation' test and removed belt from the PS, again zero change in noise so at least that's out of the equation. I've just removed the two matched belts from alternator/water pump and surprise surprise no more noise! Not sure now how I isolate one from the other (alt from water pump)? I've got one of those endless-chain style v-belts at work that I could bring home to try running each accessory individually as I could vary it's length (I hope) to run straight across from the crankshaft pulley, is this the way to go?? cheers....
Any play in the water pump pulley?
Haven't checked it yet but will pop down and have a go at it, what would you consider acceptable?
Just checked, seems to move freely and minimal play that I can detect...
I'm guessing that the noise doesn't relate to the cooling fan clutch by any chance, I've not had any issues with over-heating etc but I'm clutching at straws here!
How about the water pump bearing??????
The fan... either unbolt it and test (don't forget to put the nuts back on or the water pulley will fall off), or lock the blades to the hub using a cable tie or something, to stop the viscous coupling from moving. Not sure if there's a good spot to fix everything together though, removing the fan may be the only way to test.
TerryA;97260 wroteHow about the water pump bearing??????
Thanks Terry, I'm guessing that's what James is talking about when checking play in the water pump pulley....
jamesinc;97265 wroteThe fan... either unbolt it and test (don't forget to put the nuts back on or the water pulley will fall off), or lock the blades to the hub using a cable tie or something, to stop the viscous coupling from moving. Not sure if there's a good spot to fix everything together though, removing the fan may be the only way to test.
OK, I might go for the individual accessory testing first as I think that might be the only definitive way to eliminate either the alternator or water pump, if neither make any noise then the next step will be the fan...
Just remove fan alternator belt and start the engine as you sad recoed alternator I'd be surprised if that's the source of the noise
Not a big job to remove upper cam belt cover you could take a quick look in there too
Too many folk replace cam belt and forget the tensioner in truth they're near stuffed at belt replacement time
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