405 auto tension idler

Just a thought,- maybe it's the alternator bearings DaveK

My 96 405 td estate (XUD engine) used to vibrate and rattle in exactly the same way, I removed the wheel arch cover and found an adjustable pulley at the bottom of the engine, after adjusting the pulley , the vibration and noise stopped,

HTH Fitzy

I had this, and was told by the dealer that is was quite normal. Indeed the engine is still running fine 50,000 miles later. The manual tensioner on the underside can make a difference. Just tighten the belt slightly.

Brian.

in news:Jtyvd.39$ snipped-for-privacy@newsfe1-gui.ntli.net, "brian" slurred :

Thanks guys.

I don't know about the alternator bearings (davek), although the alternator isn't making any unusual noises, but I have tried altering the belt tension using the manual adjuster, as Fitzy and Brian suggested. Slackening the tensioner reduced the rpm at which the vibration occurs, whilst tightening it increased the rpm.

I've set the tension so that it only occurs at rpm just above tickover, i.e. a speed that I never drive around at. I'm sure it shouldn't happen, but at least it's not an uncommon problem!

Thanks again, Albert

Usually the only cure is a new tensioner assembly, and it is a sod of a job to change. Am I right in assuming you have air conditioning? The correct way to tension the belt is, at the rear of the tensioner you have to line up two holes and pin (special shaped long pin), fit the belt, adjust the bottom manual tensioner up till the pin can be removed (no longer held in the two holes under tension). The trouble is if you leave it, the tensioner will get worse and the wheel will rub against the cam cover, which is very noisy!! The way you have set it now gives too much slack in the belt, and there is a danger of slipping with load on the alternator and the air con on.

Good information there Nigel,, I wondered why it had a manual adjuster and a spring loaded tensioned on the same belt,,,,,,,,, Cheers Fitzy