VAroute66
Well-known member
I have a ZZ502 that was broken in but has never been in a car. I am able to run it in on a test stand. There is a rapping noise that comes from cylinder number 8 best I can tell from the the head. Its hard to tell if its coming from the upper head or the noise is being transmitted from the piston through the cylinder.
- The noise is not present at idle
- It does not change with temperature (Pretty sure not piston slap)
- most prevalent during rapid changes in RPM. If I bring it up slowly, it will not make the noise. Quickly, it will. Backing off can hear but then sounds more like a lifter noise.
- Next test will be to remove coil from that cylinder to see if noise changes and check valve adjustments.
Is rod knock always present at idle even in its early stages.
Any thoughts/advice/condolensces before I start tearing it apart? Thanks for your thoughts.
Route66
- The noise is not present at idle
- It does not change with temperature (Pretty sure not piston slap)
- most prevalent during rapid changes in RPM. If I bring it up slowly, it will not make the noise. Quickly, it will. Backing off can hear but then sounds more like a lifter noise.
- Next test will be to remove coil from that cylinder to see if noise changes and check valve adjustments.
Is rod knock always present at idle even in its early stages.
Any thoughts/advice/condolensces before I start tearing it apart? Thanks for your thoughts.
Route66