Volvo 940 - belt whistle/whine

[cjboddy]

Hi,

I did read Lee's findings and note the bracket issue. I am puzzled though as to why lubricating the pulley on my PAS pump does ease the noise for a few days. If the bracket was worn / miss-aligned then surely a spray of oil on the pulley wouldn't affect that??

My thoughts are leaning more to the PAS pump been the issue and some bearings dried out possibly on it?

Thanks
Craig

[ericbeaumont]

I reckon that the bracket mis-alignment spins the the pulley at a slight angle and causes the belt or pulley to rub something theyw shouldn't.

The fact that it stops instantly when I throw water at the belt and pulley suggests that it's an exterior belt/pulley issue. Surely water couldn't get into a bearing that quickly?

Road side spanner work will have to wait for warmer weather. In the meantime, I'm going to track down some of Alisdair's belt dressing.

[RollingThunder]

I've had the same issue for several months now - as intimated in earlier explanations, the cause is that the belt isn't running 'true' in the groove of the pulley, so as the pulley rotates, taking the belt with it, the belt isn't sitting flat in the groove and it rides up/down the side of the groove - this movement of the belt is the squealing that you can hear.

I've found a small tube of silicon grease in Maplins (£5 a tube so not cheap, but if it cures that incessant squealling!!!) so I'll be trying that this afternoon. I think a tiny smear of the stuff will do the job - its very sticky and waterproof so it'll stay put on the pulley, but hopefully won't affect the drag on the belts too much. It'll either work, or I'll need all new belts and a thorough cleaning of the pulleys lol.

[Michaeleff]

Always well worth ensuring that the belts are within tolerance on external size and profile.

Far too many generic parts simply are not.

Good knowledge starting point here:

See Here:

(P.S. I use them to supply Kevlar driving belts for lawn tractor and they are very helpful and obliging. Far cheaper too!)

[RollingThunder]

Having started the car from cold a few times (which is when the belt screeching is worst), I can say that the silicon grease trick is a ... success!

The belts are genuine Volvo ones and correctly tensioned, but they still screeched all the time, only slightly quietening down when the engine was hot, but now they're quiet all the time. Bliss !!! Well worth a fiver

[Michaeleff]

Originally Posted by cjboddy

Hi,

I did read Lee's findings and note the bracket issue. I am puzzled though as to why lubricating the pulley on my PAS pump does ease the noise for a few days. If the bracket was worn / miss-aligned then surely a spray of oil on the pulley wouldn't affect that??

My thoughts are leaning more to the PAS pump been the issue and some bearings dried out possibly on it?

Thanks
Craig

Useful tech info here from Gates, who of course manufacture a wide range of belts including toothed timing belts.

Here:

[ericbeaumont]

Had a look at the Gates link for a 230FK https://www.fcpeuro.com/products/vol...conti-119x1013 and came away confused: they say PAS belt is 11.9 x 1010. http://www.swedishautoparts.com/940/...&-pulleys.html list belts of different lengths from Gates, and https://www.fcpeuro.com/products/vol...conti-119x1013 came up with something different again.

After that quick google I found this http://www.volvoforums.org.uk/showthread.php?t=120652c which mixed the options even further.

No wonder it's easy to fit the wrong size belt. Is there an authentic, genuine, correct list of belt specs. available for AC and non-AC engines?

[Michaeleff]

Well, having faced this problem some years back, Eric, with my lawn tractor in France, as I always tend to do, I reverted to first principles.

Core problem was it was sold retail in France: but manufactured in the USA by American Yard Products (AYP); who had been hoovered up as have so many leading agricultural and garden power tools by the dreaded Electrolux Corp in Sweden!

Who are perhaps the most unhelpful company on this globe and are utterly uninterested in service assistance and technical support on any item more than a year or two old...

Thus I measured the pulleys; overall diameter; internal diameter; exact V or B or A profile; depth of belt; etc. And finally measured the total working size between drive and slave pulleys (and drive, idler and clutch pulleys) with a stout piece of non-stretching nylon cord!

Ponder this: Variant possibilities!

Wedge Belts: SPZ, SPZX, SPC sections:

V Belts: A, B, Z sections:

Double Sided Hex Belts: AA, BB section, etc.

The problem to my mind has been the vast proliferation of all basic car model variants: and the different design specs of each and every variant!

The Automotive Pattern Part (Generics) industry has mushroomed with ubiquitous car ownership; and all too often a part is sold as suitable, only because its specification is nearly correct.

Unfortunately, "Nearly correct" with a drive pulley and the torque involved (PAS belt particularly) is simply not good enough. If the belt sits above the pulley profile, or beneath it, then its load bearing surface is insufficient and the belt overheats, decomposes, glazes, frays, slips etc.

Belt lubricant merely masks the underlying problem/s.

Misalignment (twisted pulley; bent bracket; incorrectly placed component mounting holes in bracket, etc.).

I underwent a refresher course in torque transmission by belts, when I started playing lawn tractors circa 14 years ago!

If the belts (One to drive the cutter deck; One to drive the 4 speed transaxle)) are too long, wrong profile, whatever, then a nasty burning rubber smell rises up from underneath!

And the damned Kevlar belts are bloody expensive.

[lnparry]

Just some feedback on earlier posts:

I can certainly say that my squeaky steering pump belt was definitely due to pulley misalignment (due to worn brackets). The belt was so misaligned it wore a grove in the plastic timing belt cover! Fortunately not all the way through though.

Like Rolling Thunder the silicone grease seems to have done the trick for me as well. Now to find another noise to worry about!

Cheers all,

LeeP

[ericbeaumont]

When warm weather arrives I'll take of the PAS bracket, check it for wear; if good, replace and fit Volvo OE belts (surely they must get it right).