My '24 Touring has always had a disconcerting knock ever since I bought it. I believe that it's from excessive camshaft endplay, but I would like to see what you all think. Of course, it's very difficult to describe an engine knock, but I'll do my best.
The sound is loudest when its cold, and its more like a loud tapping/clacking sound.
It is very inconsistent as the engine is idling.
Lowering the throttle seems to help at idle. The knock also gets quieter when I'm driving it.
The noise disappears at 15-30 mph, and accelerating or decelerating doesn't cause it to reappear.
Shorting out any one of the spark plugs does not change it.
Now for things that I've replaced. The crank pulley is nice and tight on the crankshaft. I installed new bushings in the fan pulley, and that eliminated a separate knock that I was having. The generator gear is also good and tight on the generator shaft.
Cameron, I had one that knocked like that and it ended up being the shaft on the brake drum was broke but the way it was broke it could not slip past each other drove me nuts to find it?
Mine does that with the aluminum cam gear, has gotten worse as I drive it more , presently near 40 k on this overhaul. Notice I said overhaul, not rebuild. KGB
How are your cam bearings? My 26 makes a similar noise as yours. It has aluminum cam gear and the cam bearings are very loose. I can grab the end of the cam and wiggle it probably 1/16" back and forth. It runs great but replacing the cam bearings is on my to do list.
How's the pin through the front pulley? I had one with a loud tapping at idle, but at faster speeds it would disappear. It turned out to be the pin moving up and down as the crankshaft rotated, but when it got going fast it would not move up and down. I put a crimp right in the center of the pin and re-installed it. That fixed the problem for me.
Also another knock which is louder when the engine is cold is loose aluminum pistons. They slap back and forth at slow speeds when pulling. After the engine warms up and the oil gets splashed up around the pistons and the pistons expand with the heat, the noise either disappears or gets much quieter.
Norman - That last paragraph of yours leads right into previous discussions we've had on the forum about why aluminum pistons are "cam-ground", right Norm?