Tappet(lifter) Noise
 

Have a 28 AA that I just got back running after around 40 years of sitting. Ran when parked, just got parked and forgot about! Been in family for 70+ years. So once I got it running it ran pretty good, ran it it shop multiple times with good results. After maybe 2-3 hours of run time I have developed a knock or clicking sound. After some trouble shooting I have found the noise. Its coming from the tappet on cylinder #2 intake side. Still has the non adjustable tappets. While turning engine over with hand crank the noise comes when the #2 intake tappet just starts to rotate and lift. If I turn engine over real slow it won't do it, the faster it turns over the loader it gets. With tappet in relaxed position i can rotate the tappet with ease so don't think it's stuck. Any thoughts on this.

Can someone school me a little more on how and why the tappet rotates? Is the valve also supposed to rotate?

Re: Tappet(lifter) Noise
 

The tappets should rotate, the valves not usually in the a, how much clearance between the tapper and valve--- if yo put a feeler gauge in to take up the space does the noise go away---- when it is running and shorting out #2 spark plug does noise change

Re: Tappet(lifter) Noise
 

The tappet and cam follower are the same thing on a side valve motor. The cam follower rotates to avoid the flat face which contacts the camshaft suffering undue wear. Without rotation, it would quite quickly develop a groove where the cam presses. The rotating tappet also causes the valve to rotate, thus keeping wear at the valve seat uniform.
Hope that helps.

Re: Tappet(lifter) Noise
 

Noise does not seem to change when shorting out that cylinder. Haven't checked the gap yet. If i put a little pressure down on top of valve while hand cranking it over the noise goes away.

Re: Tappet(lifter) Noise
 

Thanks for the info. I kinda thought the valve would rotate also for seat wear. But I really couldn't see any of the valves rotate while turning engine over. You could see them maybe try but they moved very little.

Re: Tappet(lifter) Noise
 

Here's a short video. If it works!

It would be the valve right in front of the distributor.

https://photos.app.goo.gl/VEfpaUu2vwAiLFHj6

Re: Tappet(lifter) Noise
 

The video doesn't seem to show anything out of the ordinary. It shouldn't make any noise turning over that slowly and it doesn't look as anything is sticking. What is the clearance ? That is the biggest question right now. Anything over about .017" will make a little noise while running, very little noise.

Re: Tappet(lifter) Noise
 

Check for a broken spring when you get in there to measure the gap.

Re: Tappet(lifter) Noise
 

Yeah its a little hard to hear in the video, but it's a pretty load snapping sound each time that intake valve starts to rotate and rise. First couple revolution of cranking it didn't make any noise until i picked up some speed cranking. Tomorrow Ill check the gap. Thanks

Re: Tappet(lifter) Noise
 

The valve spring on the valve in question looks different than the others, more coils and the way it sits on the keeper.

Re: Tappet(lifter) Noise
 

That's what I noticed first. Maybe weaker spring???



TOB

Re: Tappet(lifter) Noise
 

Weak spring is something I thought of also. Specially after I would put a little pressure on the top of valve and noise would stop.

Re: Tappet(lifter) Noise
 

Perhaps a sticky valve?. The motor sat for a long time. Try running some Marvel Mystery oil in the gas and the oil

Re: Tappet(lifter) Noise
 

I've ran it in the gas sense start up but not in the oil.

Re: Tappet(lifter) Noise
 

Perhaps a worn valve guide so that the valve doe not contact the seat on center? Or worn timing gear? During part of one revolution of the camshaft, 1/2 the valves are being pushed open by the cam lobes, then for part of the revolution 1/2 the valves are closing, and spring pressure pushing on the cam lobes pushes the cam gear ahead of the crank gear. When the gear teeth are worn, the cam actually snaps back and forth, causing a clicking noise.

Re: Tappet(lifter) Noise
 

I say a sticking valve, slow to close. Try some marvel mystery oil in the gas. this happens to a engine that sits a long time. Or if you have the head off try oil on the valve stem.

Re: Tappet(lifter) Noise
 

Cams are ground on a slight taper to induce tappet rotation, the valve does not rotate unless special spring retainers have been installed, as on some heavy-duty truck engines. If your valve clearance is within specs, I would think as George does, a sticky valve. If the valve is the cause of the problem, it won't hurt to drive the truck.

Re: Tappet(lifter) Noise
 

.012" clearance on the valve. Removed the valve spring, it looks good. Probably put a new spring back in just because. After spring was out, valve spun and went up and down free. Tappet moved free. Really didn't find any smoken guns!

Took the side cover off the timing gear and it looked and felt good.

Re: Tappet(lifter) Noise
 

There is a good chance that you are hearing the valves beginning to stick. If you ran any old fuel thru it the valves will start to stick. I'd run a tank of fuel thru the engine while driving it with about 10 ounces of Marvel Mystery oil in it. If the valves are starting to stick this should free them up. Normally I run about 4 ounces of MM when I fill up.

Re: Tappet(lifter) Noise
 

I didn't see much wrong from the video, but,,,,, its hard to tell much from it.
.012" is fine and it looked as though the valves were working freely. I'm wondering if there may be a lot of guide wear. That might be something to check before putting it back together.