Exhaust rattle, help needed

[Awretham]

Ok Im at my wits end now, I really need help/input from others.

Basically my car has developed the most annoying rattle! Though it only happens between 1900-2000 rpm when accelerating meduim - heavy, and doesn't happen in 1st that I have heard, only in 2nd and above.. Also it sounds like its coming from just below the driver/passenger, but I have removed the system and can't see any problems with the center section silencer/baffles.. Im at a total loss with what the problem could be, and ANY input/ideas would be very helpful. I was also wondering, there have been references made to the bolts & springs which hold the cat to the manifold down pipe, could this rattle or ping when over tightened?! Cheers all

[SaxoAL]

possibly yes, as when it heats up it expands doesnt it, the idea of those bolts with the springs between them and the spring cup is so that they can cater for them expanding. If they are tightened to tight then rather than the spring contracting and expanding it may be causing the exhaust to rattle where it connects with the downpipe. Thats why it is recommended when, for example replacing the cat with a decat pipe, that the bolts,spring and spring cup are replaced at that time aswell to reduce the chances of the old ones being overtightened.

[Scott]

they cant over tighten though the thread stops to stop over compressing of the springs.

From memory i already suggested the cat cover to you but you have a decat pipe. I would check the bolts are tight and visually around just in case it is in contact with something. If you cant see anything it might be time to get the front end jacked up and supported on axle stands and very carefully get a mate to run the engine while you check around for the noise

[mcneill1873]

Sounds like you've got a problem known as pinking to me. Quite common with Saxos. Run your car on Optimax for a few weeks this will clean out your system which will get rid of the rattling noise you can hear.

[Scott]

i would have said pinking if his troubles had been at the top of the rev range but that low down it really shouldnt be running lean but try the optimax and see how you get on