YELLAHEEP
NAXJA Forum User
- Location
- Littleton, Colorado
'89 Comanche, 2.5L, 2wd, 5 speed 170K+ miles.
Engine seems to run pretty good, with a bit of a "rythmic miss" in the exhaust but really loud under/around the valve cover - sounds just like a 4cyl diesel injection pump rattling away.
Pulling the spark plug wires one at a time didn't affect the noise at all.
Higher RPM's make the noise almost go away.
I removed the valve cover and there's plenty of oil getting to the valvetrain. Nice and wet under there - and surprisingly clean too.
Noise seems to be loudest toward the front/top of the engine but hard to tell - it's friggin' noisy at idle.
I removed the rocker arms, push rods and lifters from cylinder #1 and I don't see any unusual wear to any of the surfaces. Looked down at the cam lobes and they appear fine as well. When tightened down and rotating the crank, all 4 cylinders appear to have good open/close motion at the rockers/springs. The rocker arms are pretty tight - hard to get them to "wiggle" at all even when at the low part of the lobe. Push rods are snug, but will spin by hand until loaded.
Read a thread over on Comanche Club forums that the "diesel" noise has been found to be a loose timing chain? Anyone else had this experience? Maybe my valvetrain is fine and the "rythmic miss" I'm hearing is actually some poor valve timing caused by the loose chain?
Thanks in advance!
Engine seems to run pretty good, with a bit of a "rythmic miss" in the exhaust but really loud under/around the valve cover - sounds just like a 4cyl diesel injection pump rattling away.
Pulling the spark plug wires one at a time didn't affect the noise at all.
Higher RPM's make the noise almost go away.
I removed the valve cover and there's plenty of oil getting to the valvetrain. Nice and wet under there - and surprisingly clean too.
Noise seems to be loudest toward the front/top of the engine but hard to tell - it's friggin' noisy at idle.
I removed the rocker arms, push rods and lifters from cylinder #1 and I don't see any unusual wear to any of the surfaces. Looked down at the cam lobes and they appear fine as well. When tightened down and rotating the crank, all 4 cylinders appear to have good open/close motion at the rockers/springs. The rocker arms are pretty tight - hard to get them to "wiggle" at all even when at the low part of the lobe. Push rods are snug, but will spin by hand until loaded.
Read a thread over on Comanche Club forums that the "diesel" noise has been found to be a loose timing chain? Anyone else had this experience? Maybe my valvetrain is fine and the "rythmic miss" I'm hearing is actually some poor valve timing caused by the loose chain?
Thanks in advance!