Rattle at idle

Kowalski · Post by **Kowalski** » 14 Sep 2006, 17:17

My Xantia has a bit of a nasty rattle at idle, a bit like a top end knock. It appears to come from the top end of then engine, rocker cover area. I've had a metal bar on to listen, and it can be heard on every part of the engine.

The thing is, when you rev the engine up to 1200rpm or so, the noise disappears completely, its only there at idle, hot or cold. I've had a look at the obvious things, e.g. exhaust, aux belt, crank pulley, and nothing seems to be wrong there.

Its not clutch or gearbox related, putting the car in gear and slipping the clutch has no effect, it doesn't appear to be related to throttle position either.

Any ideas?

AndersDK · Post by **AndersDK** » 14 Sep 2006, 21:32

Have you tried removing (not just looking at) the aux belt and run the engine ?
This will immediately narrow in on your problem search.

Post by **RichardW** » 15 Sep 2006, 21:17

Mine is doing this too - and is worse since fitting a new aux belt last week. I think the spring is knackered in the automatic tensioner, and the belt is whipping, which is causing the the automatic tensioner to bottom out causing the metallic clank. I doubt mine is getting changed, since it is dealer only, costs about £80 and takes about 4 hours to change (done one before!). I've slacked the belt off a bit which helps, but that makes it slip when using the PAS at idle after a cold start with A/C etc on. Can't win really

Kowalski · Post by **Kowalski** » 17 Sep 2006, 09:36

I found out what my rattle was....

After cracking each injector union, thinking maybe a dodgy injector was the cause, it turned out that they were all fine. So, next I took the drivers side wheel off, and had a look at the belt, all looked fine. I then tried turning the engine over to watch the belt, I did this with my ratchet on the crank pulley bolt. The bolt turned rather than the engine turning over, almost a full turn of slack on the bolt before it was tight enough to turn over the engine. So, I've now tightened that bolt in the way that Haynes says (which felt excessive) and put lots of threadlock on the threads. When I had the pulley off last time, I put a little threadlock on and tightened it until I though it was tight with an 18" breaker bar. When I tried following the Haynes process (30 lb/ft then another 60 degrees) the breaker bar just would not do the job, I had to borrow a 3/4" ratchet. Its now tight and the rattly has gone.

Lots of people have posted about having big problems shifting it their crank pulley bolts, I didn't have trouble getting the pulley off my car when I did the cambelt, the pulley bolt can't have been tightened as tight as it is supposed to be!

I still find it strange that a rattle on the end of the crank sounded like it was coming from the top of the engine...

citronut · Post by **citronut** » 17 Sep 2006, 11:09

its always supprising how much a noise can trasmit,i always tighten these with just a 2' knucle bar and never have any problems,good job you found that before it came right of,and Richard just mind your tentioner dont give up as this can cause you cam belt to slip when the AUX drive belt comes of and get in under it
regards malcolm