Got the noise to go away this afternoon. It has been a loud mechanical
tapping noise at idle.
Last weekend, I poured about a pint of Marvel Msytery Oil on the rocker shaft
with the engine at idle and down all of the pushrod holes and let it run for a
few minutes with no change in the noise.
This afternoon, while doing some checks, I remembered that someone asked if
the noise changed with RPM. I had not run it above idle so far as I didn't
want to do any damage. But, I decided to run it at higher RPM anyway to see
what happened. The frequency of the noise did increase with increased rpm. I
gave it several hard raps of the throttle and the noise went away. Gave it
several more raps and it came back to various degrees with more or less noise
and a little rough running of the engine, and I got the noise to stop again.
I stopped the engine, added the rest of the pint can of Marvel and added about
1/2 quart of oil and ran it with no noise for about 10 minutes at idle. Ran
it a little higher in rpm (2,000) a few times and no noise.
When I checked it with a stethescope last weekend, the noise appeared to
coming from the #2 cylinder cam/lifter area.
I suspect I had a sticking lifter (tappet), and since the noise went away it
wouldn't be something more serious like a wristpin or connecting rod bearing.
I think I will change all 6 tappets. If I don't change the tappets and it
sticks again I sure wouldn't want to do any damage at highway rpms.
Does it sound like I am on the right track?
Thanks,
Frank
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