I was on the highway boosting and then my motor sounded funny. Sounds like something is RATTLING. For example, a bracket mounted on the firewall and its loose and rattling against the firewall. I took off the valve cover. Seems as though the (not sure what they are called but the cams push on them and they push the valves) are pretty loose. I wiggled it and it makes a rattling sound. Doesn't sound like valves tapping though. Valves tapping would be "TICK TICK TICK". But this, Its just a rattling noise.

At idle, it makes a very loud rattling. And idles at 1,000 rpm then drops to 750 rpm...then it stays like taht for a little bit then it just drops down to almost stalling out then jumps back up ...then jumps down and up and dies.

But if I rev it to 3k+, the noise dissapears.

Oh yeah, it boosts FINE too.

Do you think I bent a valve? I didn't misshift or anything either. Just redlined it in 3rd and then I was cruising and heard that noise.

 

same thing happend to me

 

Maybe. No way to tell until you run a leakdown test or pull the head and liquid test it. Even with the leakdown test, it might not show anything alarming.

When I tapped a valve, there were no physical signs of it hitting the piston. No actual leakdown test with a gauge was performed, but we did pressurize the cylinder with the valves in each cylinder closed, and found nothing. No leaks could be heard.

Compression test did show a 160 point loss in compression in the one cylinder that was later found to have tapped the valve.

Forgot....course of action:
Regardless of any speculation....run a compression test and see if you lost anything or have excessive variation in compression b/w cylinders.

If no loss in compression, then re-align the cam timing and recheck the valve clearances to help that sound out.


[Modified by IN VTEC, 1:01 AM 9/5/2002]

 

BTW, the rocker arms are allowed to move up and down freely. As long as the endplay (side-to-side freeplay) isn't out of spec, then that movement is normal.

 

that is solid advice. your rockers could have come loose, hopfully everything will come together for ya. do what he said

can you hear the rattle only at 3K, maybe if you zap the throttle quickly but WOT it goes away? Hmmm... that sounds like it could be a rodbearing. this is what mine did when it began to spin. WOT the sound was transparent but narrow throttle and a quick ZAP of the throttle under 4K would reveal its ugly head. a knackaknacka like as if there were marbles in my engine...

 

found out what happened...I cranked the motor by hand and what do you know, the timing belt is skipping. Tensioner somehow got loose.

I set everything back to TDC and retorqued it to 40 ft-lbs+

Hopefully this wont happen again!

 

whew...!