340 CVT belts squealing

[nomead]

Still trying to figure out that belt squeal... Now it's slowly getting worse. There's a squeal from the back that sounds like slipping belts (similar to a slipping alternator belt), and it used to come only with cold belts, and then it went away. Now it's always there, under acceleration and worst at between 30-40 km/h (at higher speeds it stops). I thought it would be due to a long overdue tension adjustment. But today I finally got under the car, and the pulley gap is a bit over 1.5 mm on both sides. I only had a 1.5mm measuring stick and it had some free space on both sides, so it's an approximate measurement. Also, the belts looked fine. No cracks whatsoever and not much wear.

The car lift I was using was a drive-on model, would this affect the pulley gap measurement i.e. do I need to lift the rear wheels off the ramp and let them roll freely to a halt?

Also the V-shaped adjuster bit between the primary and secondary units was missing a mounting nut. The other mounting nut+bolt were there but loose. Anyway this shouldn't matter during normal driving conditions because then the secondary unit is securely fastened to its mounts, but I guess I'll have to get new parts just to feel safer (it's just a M8 x 80 bolt and I thought I'd put a nylock nut there now).

[nomead]

Took a few pics and downloaded them from the camera...

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First pic, the protective undertray seems to be quite broken. I guess it's a side-effect of the Finnish winters, having lots of ice chunks on parking lots etc. Mostly snow that's melted on the surface then frozen again. 20 winters of that will do wonders to any underbody component, and plastic is extra nice because it gets fragile in the cold. Anyway, the missing front piece allows splashes of water to land directly on the belts, and actually there was a largish chunk of ice on the inside of the tray.

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Second, a pic of the adjuster as I found it. For some reason I wasn't able to get that bolt end through the corresponding hole in the adjuster bracket. Maybe my hammer was too small. (For those not familiar with the CVT adjuster layout, the large bolt in the left top center is the actual adjuster bolt; the loose bolt I'm talking about is to the upper right side of the adjuster bracket).

[morgan105]

Looking at the pic it looks like the adjuster plate is bent way out of shape, if it is you won't get the standard bolt through the hole until it is re-shaped, best to take it off and heat it up and straighten in a vice.

If they are new belts they may be of a stronger material. If they are Roulands they are tougher made on the side walls and do tend to screach for a while (wifes nagging me to change them) but sometimes a build up of material sticks to the pulleys and causes the noise but even with cleaning these it is not a guarentee the noise will stop. I cleaned them up once and they were fine for a day but back to screaching the next but once warm they do quieten down but for how long depends on the weather. Possible the belts are slightly out of allignment causing one side to rub harder on the pulley but even with the Roulands perfectly straight they do screach. Maybe some of the box oil is getting on to the belts causing them to slip at certain revs.

[volvodspec]

considering the fact that the cvt skid plate is broken, and you drive on icy roads, the conclusion seems very simple to me.

too much moisture from the ice gets on the discs of the cvt causing the belts to squeal (and wear!). you can try to run a home-made/custom aluminium cover instead of the plastic rubbish to keep the moisture from the snow away

[nomead]

Arggh, a few days ago I clipped a speed bump and now it seems that the CVT undertray is hanging half loose and is practically in pieces. Good that it isn't snow season anymore... but this calls for some inventive fabrication, as soon as possible.