-
Severe tick when warm
I know online diagnosis is a crap shoot, but here goes.
I took my 54k mile 79 D-50 on a 3 hour interstate drive pushing it harder than I should (75mph). When I stopped for a snack, I noticed a bad tick that rattles when revved. Thinking cam problem/ valve adjustment I pulled the top cover to find a very loose timing chain. While changing both chains, gears, and guides, I noticed the bolt on the oil pump shaft had backed out and was grinding into the cover. Cover welded, bolt replaced, and all back together hopeful I had solved the issue. No dice. Engine is quiet when cold, but the loud tick and rattle when revved still exists when it warms up. It's hard to tell where the noise is coming from even using a stethoscope, but it seems like
Maybe in the area of the front cover/balance shaft area. I've adjusted the valves several times, and inspected the valve train and jet valves with no change. I've searched but can't find the symptoms of balance shaft bearing failure. Is there a way to check the shaft bearings? I also pulled the plug wires one at a time to isolate maybe a wrist pin or bearing issue there, but the noise is the same regardless. I've thought about deleting the shafts, but since I'm not after performance and prefer all stock I'd rather fix the problem.
-
check the oil pressure when the motor is at operating temp - there is a port on the right side of the motor by the oil filter that you can plumb in the gauge. Oil pump screen could be sludged up or a weak pump
-
Is the head mechanical or hydraulic? If it's mechanical, the tappets might need adjusting up - if they're hydraulic you can try performing an engine flush to clean out the hydraulic tappets. The valve train is the primary source for noise. If the noise still persists you may need to replace the hydraulic tappets.
-
I'll check the pressure. Judging how spotless the timing and valve cover area were, I doubt sludge
Is the issue. I had the oil pump apart during the chain swap and
It looked brand new inside. The oil light goes out the instant it starts, but the pressure still could be low I guess.
The engine was always super quiet, I'm baffled at what could have let go.
-
It's a mechanical lifter motor. Been thru the adjustment multiple times, pretty sure it's spot on. You're right the noise sounds like a loud lifter noise although the rattle as its spooling down after a rev is weird, as is the fact it's pretty quiet until warm.
-
are you sure the timing is set right? maybe the vacuum advance is sticking and the ticking is pinging or low level detonation. I was getting ticking in Geronimo and changed to e0 gas - ticking is gone - its also 89 octane instead of 87 - runs like a top with lots of power
-
Oil pressure is great. 75 cold and 50 warm. Tried pouring ATF in the carb while idling in case of a sticky valve to no avail. Looking online, seems that the tick with a rattle or double click on decel could be a wrist pin. Not sure why
That would get louder when warm though. My experience has been most loose clearance noises are worse when cold and this noise appears when warm.