Hey guys, I've got a new rattle that I'm REALLY worried about... It started at the autocross this morning, and I was able to get it to make the noise a little on the way home too... Under load in second and third gear, past 5K, I'm getting a "rattle" from under the hood... It was doing it real bad at the autocross, so I stopped running. Definitely not as bad on the way home the couple of time I could do a 2nd/3rd gear pull... Could it be detonation? I think the reason it may have been worse at the autocross was because the cornering loads placed on the car would keep the bowls from filling all the way. Opinions? Ideas? Help me diagnose this guys!!!

Dan

 

yah it could be detonation. any black smoke out back right before/during the "rattle"?

mike

 

Change your belts.

 

Belts are brand new, why would they cause this noise?I haven't seen any smoke, but that's understandable considering I was paying too much attention to the course... Do you think the rattle was from the belts slapping?

Dan

 

Make sure all belts are tightened. I had a single belt under my hood (no accessories). It was worn and slightly loose, around the RPMs you described it would sound similar to a small bell ringing, i replaced the belt and tightened it down securely, no more noise.

 

does it sound like popcorn? thats BAD

 

Not giving us much to work with. What are you mods to the car?
WHat your timing set at?

Do you still have ANY exhaust shielding on the car, had that more than once, thought the car was going to blow up.

John

 

sorry, power mods are very minor. RB air cleaner and header, Mintrain cat back exhaust... Timing is set at stock... All the heatshielding under the car is still intact. The car has been very well maintained, with all filters and fluids being changed on schedule. car currently has 67K miles.

 

I personally think it could be timing

 

Did you try tightening your belts?

 

What if your belts are a little too tight?

 

If it sounds like sand or tiny pebbles swirling around inside a tin can, then it is your timing

 

a rattle usually means something is loose....maybe a sway bar or some other suspension piece. Is the car down on power? Can you feel the rattle threw the steering wheel, brake pedal, clutch, etc?

 

Good idea, check suspension, wheel bearing and Idler arm bushing rotted, that could cause some serious knocking.

John

 

Can't feel the rattle at all... car did not feel down on power

Dan

 

um...this may be of no help what so ever, but i had a rattel for the lobgest time and could not figure out hwta it was...then one day...determined...i went under the hood and tightened every bolt i could find...then i leaned on my fender and admired my work, when i realised that my battery tie down was loose and rattling...hink small before you go to the big stuff.