M18 Noisy

[RLause]

Hello. I've been lurking here for the past year when I got my first Cub, a 127. Since then I've purchased 3 more, a 125, 109 and a 1862. The 1862 had a broken rod. I found a M18 engine that the PO said was getting noisy. The noise seems to come from the lifters or valves. I checked the valve clearances and they are within spec. I have never been around a M18, but have been working on engines for 60+ years and this has me stumped. Does anyone have any suggestions? I will post some pictures soon.

Richard

[dvogtvpe]

I don't much care for any of the opposed twins, I'd be looking more at piston slap or a loose rod. flat head solid lifter engines generally don't really have valve noise

[Leadslingingdaddy]

I have read that after a 1000 plus hours the Mags start getting lifter noise from tolerance issues.

[dvogtvpe]

lifter bores in the block wear out?

[RLause]

I forgot to mention the engine has 1100 hours on it. The oil pressure at idle is 45 lb. picking to 50 lb. at high idle. The noise is definitely clicking like a valve tappet and not a loose rod. Thanks for the ideas.
Richard

[J-Mech]

Originally Posted by dvogtvpe

I don't much care for any of the opposed twins, I'd be looking more at piston slap or a loose rod. flat head solid lifter engines generally don't really have valve noise

I agree with Don.... but not about not liking the opposed twins, but about the valve train noise. Seriously, are you sure it isn't the muffler. When the insides of them start coming apart, it can sound like the noise is coming from the top end of the motor. Also, pull the tin work and see if you have a head or exhaust manifold gasket giving away.

[clint]

I have one making noise, it's hard to isolate, but mine ended up being front main bearing. Really easy to tell when turning engine over by hand using ratchet/socket at front of engine (pto end)

[RLause]

Thanks for all the replies. I think I will pull the tin and check the head gaskets.
Richard

[ol'George]

As long as the valve clearance is within spec. I'd not worry about it.
Late Kohlers tryed to address the issue with 30* valve/seats and tighter clearances.

[RLause]

Hello. I split the engine and the end play on the camshaft was .013", the max play allowed. I used a .010" shim to bring it down to the min play of .003" and it sounds like a new engine. With the Helical Gears on the camshaft, when a valve was beginning to open, the cam would slide to the one end. After the valve when over the top of the lobe, the valve was pushing on the cam, forcing it to the other end of the shaft. This caused a click every time the shaft slid back and forth. Thanks to everyone for their help. Maybe this will help someone else.