Squeaky V belts

[marshmat]

The problem:
A hydraulic pump (for steering assist), engine mounted, is driven by a conventional V belt.
After a cold start, this belt squeals like a banshee for the first 30 to 60 seconds. The squealing is much worse when a load is applied to the hydraulic pump.
The noise is much worse in wet/humid weather.
Once things start to warm up, it runs smooth and silent.

Already tried:
The belt is new. (About 100 hours since it was replaced; the old one had never made any sound in 500+ hours of service.)
I've already adjusted the tensioner, twice. No appreciable improvement.
There's no evidence of grease or oil on the belt or the pulleys.

Anyone know of any belt dressing compounds that actually work? Or has something obvious been missed?

[Milehog]

Is the belt really the correct size? It could have been mispackaged. There should be a part number on the belt itself to check this.
I've also gotten belts that had been sitting on some stores shelf for years that were were problematic till they died a premature, catastrophic death.
Did a pulley somehow get misaligned?
Belt dressing works but I'm sure you want to find the cause before you get some unpleasent suprise.

[marshmat]

It's an OEM belt, purchased from and installed by the OEM's authorized dealer, and the belt and pulley widths do match correctly.

Pulley alignment is, as far as I can tell, within tolerance.

[Adler]

Dear,

The applied type of belt to Hyd. transmitters is SPAX or SPBX or SPCX ,etc
and not SPA or SPB or SPC etc.
The reason is that the belt type with "X" have teeth to their body , able to fit
the cross section profile of the belt to the pulley's "V" shaped cross section
avoiding to slide , to increase the temp because of friction and finally to fit
in progress - based to known diastolic causes on the belt's mass.

Just look to the following web-address about the difference.

As you know well the torque load on Hyd. circuits is much higher comparing
to other power transmitters such as electrical (generators - alternators) or pneumatics (compressors).

http://www.bestorq.com/

[marshmat]

Yes, the belt in question is the toothed ("X") variety. The pulleys are smooth V-type, not cogged.

[Adler]

Dear,

In case that you have on the Htd circuit a pressure relief valve that oriented the
pressure's value at torque limit ones that are corresponding to the permissible
for that belt please take a note to add a belt dressing of some pine resin.
This advise is completely according to practice experience.

The real solution is to regulate the nominal pressure of the circuit and to check
specially the non return valves w/order activation that blocked the Hyd. Cylinder or the Hyd. Motor to be braked when the order valve remains to middle position (0-act).

[Frosty]

Sometime belts are old after being on the shelf, --they get hard,--especially in hot countries.

The V belt should not be touching the bottom inside of the pulley it should be riding alone on the 2 V's of the pulley. There shouldf be a healthy gap under the belt.

[michael pierzga]

Hmm... I never have talking belts and I never use belt dressing. Try a new , correctly tensioned , belt on clean pulleys and make sure that the equipment is free turning and not bogging down '

As Frosty states the belt must not touch the bottom of the pulley or it will never develop enough friction.

[CDK]

I think Frosty is right. The "new" belt may have dried out while waiting for you on the shelf. Most brands have a manufacturing date printed on it.
Buy a belt from an automotive store, they have a faster turnover and charge you less.

With the old belt removed, check that the pulley walls are shiny and the bottom isn't.

[philSweet]

something from Gates-

http://www.gates.com/brochure.cfm?br...ocation_id=540

It includes a test for distinguishing between tension slip and misalignment slip which I wish I had known about sooner.

[marshmat]

Thanks for the tips, guys.... next time I look at the thing I'll try the water spray test in the Gates link, check the mfr date, etc. and perhaps hunt for another new belt.

[powerabout]

why haven't v belts be relegated to the past like points ignition

[MechaNik]

If it's the right belt and installed correctly a bit of CRC belt grip should shut it up. It is probably a bit age hardened and softens up as it gets hotter.

[tom kane]

Don`t ignore squeaky v belts as the image shows there may be sinister problems behind the noise. This is a dynamic balancer which has separated into two parts leaving the possibility that the belt pulley could run of the engine.
Impossible to detect unless the belts are taken off and a close inspection made. A screeching noise at start-up (sometimes) was a puzzle on one of my motors. The material fusing the two pars together became unstuck. This was flat belts.

On older engines the v belts became hard and shiny and some rust made v belts squeak so cooking glycerine was used to find the noisy belt and quiet temporarly.

[marshmat]

Still squealing for the first 10 to 30 seconds after all of the above, including belt dressing (helps for two days, then back to squealing). It's winter now... we'll see if it gets better when the warm weather returns, and if not, it'll be replaced.
Thanks for the help, folks