i seemed to have narrowed it down to the head. it could be the turbho but i dont think turbos will make a knock/rattle sound if they are going bad. its a z6 in 89 si with greddy kit and zdyne gold. i took the rocker arm cover off(is that what you call it?) and i removed and checked the LMA's and they didnt seem to stick. nothing looked out of the ordinary. could valve lash be off? any ideas? i have been driving the car like this for about a week and it seems to not be getting worse. it only seems to happen when you are on the gas lightly.

 

any one?

 

Any chance it's pinging? Too much advance or lean at part throttle could cause it. If it changes with throttle position more than rpm, that would be my guess. If it was the LMA, I would expect it to change at the rpm the vtec engages. If it's anything with the valvetrain, it would change frequency along with rpm changes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mohudsolo &raquo;</TD></TR><TR><TD CLASS="quote">Any chance it's pinging? Too much advance or lean at part throttle could cause it. If it changes with throttle position more than rpm, that would be my guess. If it was the LMA, I would expect it to change at the rpm the vtec engages. If it's anything with the valvetrain, it would change frequency along with rpm changes.</TD></TR></TABLE>

it does change frequency along rpm but as the rpm goes higher the car gets louder so i cant hear it.

 

That makes it hard to guess the problem. Maybe someone nearby you will reply and can listen to it? Did the sound just start all at once or build over time? It's easy enough to check valve clearance, so I would start there.

 

happened all of a sudden

 

A valve adjuster could have come loose. Pull out the sparkplugs and make sure they look OK. If it's an internal problem, one could look burned or have a damaged electrode. Was the motor ever overrevved?

 

yes. once. to about 8k but the thing is my old ls motor was bounced off the rev limiter all the time and nothign like a bent valve ever happend to it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vetter &raquo;</TD></TR><TR><TD CLASS="quote">yes. once. to about 8k but the thing is my old ls motor was bounced off the rev limiter all the time and nothign like a bent valve ever happend to it.</TD></TR></TABLE>

Ls at 8k? wow, your lucky.

The single cam is a pretty strong motor that can take abuse. I think its piston slap. Do you have stock pistons?

 

yes i have stock pistons. read my upper post better. i revved the d series to 8k once and i dont get why it would bend a valve when id bounce the ls off the rev limiter al lthe time and nothing ever happened to it.