Chuff...chuff...chuff...

[Vos]

Hey all, I have been trying to diagnose a strange sound coming from my '99 S70 T5 for a few weeks, and I am at a loss... The car runs great, and nothing is "apparent" as far everything works and there are no codes or anything, but there is a sound which sound like "chuff...chuff...chuff...chuff..." coming from either the timing belt area or the back of the block. It is RPM relative, and it only makes it when the engine is cold (the sound is not present once everything is hot).

I inspected the timing belt, it looks fine (it only has 25K on it), no cracks or anything, and I changed the accessory belt with a new one (also only 25k on it): no change. The sound is definitely not coming from any of the accessories driven by the accessory belt either (I listened with a probe).

Maybe its just the timing belt with a rough spot on it that I can't see, but maybe its something else? Anyone else ever have this happen?

Thanks for any and all input,

Vos

[turboV70]

try some belt dressing on it. maybe that'll help.

[Bay13]

might be the cover rubbing, I know the 1999 and on are hard to get on right without them rubbing. When you did the timing belt did you also replace the manual tensioner?

[Vos]

Both turboV70 and Bay13Admin, thanks for the tips!

I will get some belt dressing and give it a try... Regarding the belt cover, I could not really tell if it was rubbing, but I put about 20K on the belt before the sound started, but perhaps the cover has shifted recently and just started rubbing? I will check. On the tensioner, I did replace it last go round, but who knows, things like that have failed before!

I think my current plan of attack is [1] try the belt dressing, if it does not solve it [2] put a new t-belt on with a new tensioner, if that does not work, scratch head and take another look at it

Thanks for the advice!