Shadetreemechanic
Full Access Member
My 87 cab and chassis has had an engine tick for several years now. Motor is not original and I have no idea of miles. the tick is not consistent, sometimes loud and sometimes almost inaudible. On a couple occasions I have turned the motor off while in gear on the highway and have thought I could still hear it some so I have assumed its in the top end of the motor.
Last month after an extended interstate run the noise change and got more metallic. I got worried that something was about to let loose, so today started checking it out.
I pulled all injectors and did a compression test. Min cylinder 300, max 350. Not great, but a runner for sure. Most cylinders were around 325.
I pulled the valve covers and the rockers seem tight. I barred the motor over and checked again, and again, and again until I had run through a complete revolution. Nothing seemed out of whack. One rocker had a few thousanths of slop in it when the lobe was down, but nothing that a lifer wouldn't take care of.
I also had my son turn the motor over with the starter with injectors out and valve covers off. Everything appears tight with no odd noises.
EVERYTHING SEEMS FINE.
I was also given an injector tester recently so I tested the injectors. Only 6 would test because the PO cross threaded two, pop pressures were all over the place, as were spray patterns. Two that I could test just dribbled after 1400psi.
I had planned to pull the intake and the valley pan to double check the pushrods and inspect the lifters, but I am wondering now whether it was just injector knock the whole time.
Is there anything else I should be looking at? I am tempted to put it back together with some rebuilt injectors I have on the shelf, but I am deep enough now that I could pull the valley pan. Anyone care to advise whether its worth my effort?
Last month after an extended interstate run the noise change and got more metallic. I got worried that something was about to let loose, so today started checking it out.
I pulled all injectors and did a compression test. Min cylinder 300, max 350. Not great, but a runner for sure. Most cylinders were around 325.
I pulled the valve covers and the rockers seem tight. I barred the motor over and checked again, and again, and again until I had run through a complete revolution. Nothing seemed out of whack. One rocker had a few thousanths of slop in it when the lobe was down, but nothing that a lifer wouldn't take care of.
I also had my son turn the motor over with the starter with injectors out and valve covers off. Everything appears tight with no odd noises.
EVERYTHING SEEMS FINE.
I was also given an injector tester recently so I tested the injectors. Only 6 would test because the PO cross threaded two, pop pressures were all over the place, as were spray patterns. Two that I could test just dribbled after 1400psi.
I had planned to pull the intake and the valley pan to double check the pushrods and inspect the lifters, but I am wondering now whether it was just injector knock the whole time.
Is there anything else I should be looking at? I am tempted to put it back together with some rebuilt injectors I have on the shelf, but I am deep enough now that I could pull the valley pan. Anyone care to advise whether its worth my effort?