2007 Mazda bt50 3lt turbo diesel squealing fan belts?

[Troy381]

Hey just wondering if anyone has an explanation. I have a mazda bt50 and one of the duel fanbelts snapped the other day, so replaced the matched pair but ever since replacing there has been a squealing noise when the engine is under load. Tried re-tentioning the belts and this hasnt worked it seems to only squeal when accelerating. Could the fanbelts still be slipping even though they are tensioned? Any help would be greatly appreciated. Cheers Troy

[Peter Aawen]

If you've only replaced one belt then the noise is most likely because you've got one new belt & one old belt so the tension on the belts is not identical, so at least one of them is loose enough to squeal under load. I've been told more than once that those dual belt outfits need to be replaced as a matched set at the same time.... If you've replaced both of the matched set at the same time, then it might just take a few re-tightenings to get all the 'stretch' out of them before they settle...

[chris_stoffa]

Troy,

The Bravo WLT has the same system and it gave me grief also, once you change the pair of belts they will stretch for a little while and will require a few retensionings until they settle. And you will have to overtighten them to a degree otherwise they will just keep screaming

Once they have finished stretching they is then all good

I changed a set when I first got the unit @ 50K , then another when I cracked a head at 130K and they did it both times.
And I reckon when I change them again at about 250k they will do it all over again

Oh, and the only belts I have used is Gates

[Jimmy Wood]

Does it do it if you just rev it in neutral? If so, its the fan belts. If not, it could be escaping air from the turbo (if it has one).

[Troy381]

Ok thanks, ill have to keep an eye on it.. only does it under load it doesnt do it in neutral revs. Im unaware if it done it last belt change or not. As they were only replaced less than 40,000ks ago just under 12 months.

[Jimmy Wood]

It may be the clutch fan kicking in and locking up due to extra heat when under load, and making the belt squeal.

Next time it does it, straight away, put your foot on the clutch and give it a sharp hard rev, if it squeals, its the fan / AC / PS belt. Test which one by turning stuff on and off and holding the wheel at full lock.

If it doesn't do it, then its NOT your belts, so may be an air leak in the turbo ducting. Should be easy enough to find. Look for damp oil patches on the intake system.