[Doctor john]

I started my OHC6 for the first time this year and it had a loud tapping noise but ran ok. A previous owner, from what I can surmise from engine numbers, put a 1966 sprint in my 1967 LeMans. Over the winter I replaced accessory housing gasket gue to an oil leak. It's hard to see in the pictures but I think I got my accessorihoysing timing off by a tooth. Would that cause a tap/tick? Also, should the timing belt be between the lines on the rear cover? Mine is not close to those but does deflect about a half inch when I push on the long side.

[camerjeff]

I can't tell if the accessory gear timing is correct or not from the pictures. But for belt tension I always just set it so that you could twist the belt 90 degrees on the passenger side, I never used the marks on the rear belt cover.
Where is the tapping noise coming from? Cam cover, power steering pump, alternator? Try narrowing down where the noise is coming from, it could be a collapsed lash adjuster if it coming from the cam cover, Otherwise look for loose brackets ect...

Good luck and please tell use what you find,

[Doctor john]

I got the timing marks lined up and the problem persists. When I listen with an automotive stethoscope, I don't hear the noise from the power steering or alternator. I am not sure how it is supposed to sound, but when I listen over the valve cover I can hear the valves ticking but over cylinder #1, at the front, it sounds more like a clunk. Maybe collapsed lifter? What does that mean? How hard to fix? Can it be repaired or does it need replacement, and how available are replacements? I think there is a cleaning procedure I the ship manual, while I'm in there should I clean all of them? Thanks for your help!

[camerjeff]

It sounds like it probably is a collapsed lifter, but it also can be a flat cam lobe, you wont know until you pull the cam cover. Not a bad job but it requires removing the timing belt, lowering the coolant level about 1/2 way, then unbolt the cam cover. You say it is a 66 engine? If it is a 66 or 67 you may be lucky and it could be a broken can follower retainer. They are known to break (even though in 40 years of playing with these engines I have never had one break) so I don't know what it sounds like when one does break.
They are not needed, and where only installed to keep the followers in position when installing the cam and cover. They caused warranty issues and were not used on the 68/69 engines. If it is a collapsed lash adjuster (lifter) they are available both NOS and aftermarket. They also can be cleaned and reused. I have cleaned a few sets when installing good used parts in the past. It isn't hard. The couple I had collapse where in engines that were very sludged up and thin oil inlet hole became clogged.
I hope it is just a broken retainer, but you won't know until you pull the cover off unfortunately

[Doctor john]

Thanks Jeff, i will pull the cover and look. May be awhile before I get to it with work and the holiday coming up. Ill let you know what i find.

[Doctor john]

Got the cam cover off. The camshaft looks good, there are no missing clips. When I push on the HLAs, from front to back. The 1st. Second, and 4th depress easily with my finger. The others don't budge. Does that mean they are collapsed? Will cleaning them solve the problem or do they need replacement? Is there a way to bench test? The shop manual directs a bleed down test but it takes special equipment.

[Cammer-6]

your finger test has replaced that"special" equipment.
Pull those apart(do not mix parts) clean,soak in oil over night and pump up
while still in oil.
Most likely sludge is in the lash adjuster galley

[Doctor john]

So clean the ones I could easily depress, not the others? If they hold pressure with the finger test after cleaning, they should be reinstalled in the drained state, correct? Do I need to spin the oil pump after reinstalling to pump them up or is it ok to start or crank engine to pump them up?

[camerjeff]

I would just clean up the 3 you can depress, as already mentioned do not mix up the parts between them, also depending on which type are installed, original with the bleed restrictor in the top hole, or aftermarket ones without it. But seeing as you still have the retaining clips installed I suspect they are the original style. Make sure the 3 that you can push down have the small restrictor pin installed in the top hole if they are stock units.
The only other thing I would do is make sure the oil gallery hole is clear and not sludged up. I would probably pull out the other adjusters just to clean up the holes they sit in, and clean the oil supply holes. You can install them pumped up or not, it should not really matter as they should pump up in a few seconds after engine start.
Good find - if you ave a 1967 service manual it should have a very good procedure in it to clean and reassemble the adjusters.

[Doctor john]

Thanks! I have the manual and will clean per your instructions.

[Cammer-6]

overnight soak of lacquer thinner will cut most of the varnish

[Doctor john]

So I disassembled the 3 HLAs, soaked in lacquer thinner overnight, cleaned with brake cleaner, and reassembled with new, clean motor oil. They move freely and spring back. I submerged upright in clean motor oil and pumped the tops up and down repeatedly but they never firmed up. I'm not sure what that means. They cleaned up nicely, holes are open and nothing broken, so I'm not sure why they aren't pumping up or if they should in my test.

[Doctor john]

So I used a syringe to fill them with oil through the restrictor hole in the top and they firmed up after a couple pumps. I then drained some oil out so they were a little softer and reinstalled. I will clean the bores and holes in the others and reinstall cam cover when I get time. Fingers crossed.