A stupid question.

[Yellow 13]

There are no stupid questions. But there are alot of inquisitive idiots...

Moving on.

Is it possible to have rodknock through only a certain RPM range?
My car would have a light tapping noise through the 2500-3200 RPM range and would go away after that. I was running with out a KS for awhile since the plug broke off.

 

[92Turbo]

Usually rodknock will go through the rpm's and stay at the speed of the motor, but anything is possidle. It could bent valve or something though...

 

[IJ.]

Yes there seems to be a range where it's more pronounced early on.

I think when it goes away above a certain engine speed what's happening is the Oil Pump is supplying enough pressure/volume so you have a wedge of oil between the loose bearing and the crank preventing contact/noise.

When it is quiet below a certain engine speed there isn't enough load to displace the Oil wedge.

 

[Yellow 13]

Thanks, I think Im just gonna go ahead and replace the rod bearings while the engines broken down then.