944 Timing Belt change - strange noise...

[suckmyrockets]

Hi All

I have recently changed the timing belt on my 944 S2 and ever since doing so a noise has developed. It's an aftermarket rather than Porsche OEM belt and the reason I'm suspecting the belt is that the teeth appeared ever so slightly different to the belt removed although the ovrall dimensions are the same.

Has anyone suffered a similar problem by any chance?

Thanks in advance

[softinthehead]

erm.... fairly hard to reply to this, depends what you mean "strange noise". is it a whistling, or high pitched, or whirring, or grinding or a low moan or a rasping sound or what?

my 968 always sounds a bit different after a belt change. has a sort of electric whirring noise, sounds great, like some infernal, giant dyson.

BTW can we reply without being obliged to suck your rocket? its not really my thing (despite being a cab owner)

[johnmaddox]

If the belts make a whirring noise it is usually because they are too tight.

[Boosted Ls1]

Maybe give it 1/2" slack on the longest length and try again.

Boosted.

[hartech]

It has been reported before that some aftermarket belts - particularly with a shapr at the tip of the teeth that makes it look like a double tooth - can create windage noises as the gap closes in on the sprocket.

I cannot verify this but if everything else checks out - it could be the reason for the noise.

Another possibility comes from a new belt being stiffer than an old belt and therefore although the linear tension may be set right the load put on old rollers from the stiffer belt being forced around in curves as it passes round the rollers - could make an old roller sound more noisy - if so the noise should recede with time or a new roller is needed.

If a new cam belt is changed the same applies to the water pump as this also forms a roller and sometimes this explains why a new belt can quickly kill of an old water pump.

Baz

[suckmyrockets]

Thanks for the prompt responses Everyone. Much appreciated. In response to "what sort of noise?" this is always difficult to answer as it's entirely subjective.

Put it this way, I fitted a complete cambelt kit including a new water pump (£ouch!) and when the 'noise' first developed, I suspected it was a water pump bearing on the new pump. Stripped, inspected (water pump was fine) and re-fitted, but the 'noise' remained.

Closer inspection of the belt does indeed show that although the dimensions are exactly the same, the teeth do appear slightly different - I will try an OEM belt & see what happens.

Thanks again.

[tr7v8]

New belts do make a whirring for a while after changing. It's not too tight don't retension it, if you're that concerned take it to a decent specialist to check.
It should be retensioned after 1000-2000 miles anyway.