I’ve posted this over on the French Car Forum too.

2002 C5 2.0hdi

The serpentine/alternator belt stripped. I’ve replaced it with a new one, but there’s a problem.

I’ve checked the alignment of the belt around each pulley. When I start it up the belt around the hydraulic pulley is derailed by a couple of teeth. No mater what I’ve tried it still skips out of the pulley groove.

Could the tensioner immediately before the hydraulic pump be misaligned causing the belt to skip?

The hydraulic pump is at the upper right, the tensioner is to its left.

is the auto tensioner free (thats teh top one in the middle)- stick your long 15mm on there there and move it about a bit – it should return of its own free fill

failing that is the baring on that idler ok – the middle small one

is the surface on that idler flat – these wear at an angle and throw the belt once too worn.

start the car and watch the auto tensioner – does it jump up and down . if so check your crank pulley for occilation ,many pugs have a damper rubber in the crank pully that breaks up.

Thanks Terry, the auto tensioner is at the middle pressing down on the belt. It returns well and is tensioning the belt.

I need to check the surface of the idler pulley and the crankshaft pulley. I’ll get back on this.

The main pulley is two part with a rubberband joining the two. I’ve seen the outer start to seperate and start to work its way off putting the belt out of line.

yeah thats the damper feature ….

do also check that the 4 bolts holding the crank shaft pulley are tight / there is no movement in the pulley.

Trail Rat wins the coconut.

Sure enough the tensioner pulley was worn. I nipped down to the motor factors, they had one in stock. That was the easy bit.

Who ever designed the engine bay needs a foot up le arse. There was no space to remove the tensioner between the body and the engine. Eventually I had to pull the alternator to get it out.

All back in, running sweet again.

Pours a celebratory dram. 🙂