bypass tensioner

406jim · Post by **406jim** » 16 Dec 2010, 09:14

hi all, new to the site, got a question about my 1997 406 2.1, the aux belt tensioner snapped a couple of months ago and chewed the belt in the pulleys, driving to work this morning and it went again, the question is, can i buy a shorter belt and bybass the tensioner pulley altogether, just want to know if anyone has done this before and how much shorter i should go, thanks in advance jim

Post by **CitroJim** » 16 Dec 2010, 09:29

Hi Jim and welcome...

No, the tensioners are essential to keep the belt under correct tension. The only bypass that's acceptable is to use a shorter belt to bypass a seized aircon compressor.

The root of your problem is most likely to be failure of the bearings in the automatic tensioner and or its spring.

This causes the tensioner jockey wheel top run at an angle and throw the belt. Replacement is the only answer. You may be able to see the wheel cocked up at an angle if you sight it.

A belt that's being regularly thrown is very dangerous as it can go through the can covers and end up tangling with the cambelt with expensive results. Many engines have been damaged as a result of this.

Here is a guide to replacing the tensioner. It's based on a 2.1TD Xantia but it applies equally to a 406.

406jim · Post by **406jim** » 16 Dec 2010, 09:36

thanks, i know how to change it as ive already changed at a cost of £80, the car was a cat c repair when i bought it and the damage was the front right wing, any tensioner i fit doesn't seem to sit properly, resulting in it throwing the belt, surely with a perfect size belt i could get the correct tension

panason1c · Post by **panason1c** » 16 Dec 2010, 14:20

406jim wrote: surely with a perfect size belt i could get the correct tension

In the absence of the tensioner, it would be very difficult to fit a 'correctly tensioned' belt over the pulleys ......by the time you fit a belt that can be levered over the pulleys it would very likely be too slack and slip under load.

406jim · Post by **406jim** » 16 Dec 2010, 14:28

ive found that the tension has never been right, i think the crash has damaged the mounting. i have just bought a belt 78mm shorter and managed to slide it on whilst rotating the pulley, its running the best it ever has and the tension seems perfect, the steering is really smooth even to full lock both sides, thanks for the input guys

panason1c · Post by **panason1c** » 16 Dec 2010, 14:30

406jim wrote:ive found that the tension has never been right, i think the crash has damaged the mounting. i have just bought a belt 78mm shorter and managed to slide it on whilst rotating the pulley, its running the best it ever has and the tension seems perfect, the steering is really smooth even to full lock both sides, thanks for the input guys

'Nothing ventured nothing gained'...............well done!

Post by **CitroJim** » 17 Dec 2010, 09:02

Well, that's good Jim, at least it's all working again now.

One known problem on the 2.1TD Xantia is that there are two sizes of belts depending on the make of A/C Compressor fitted. Use the wrong one and the belt will never tension correctly.

I have no idea if this applies to the 406 but it's worth a look...