I'm hoping someone can offer me some insight because I'm afraid of running my mower, worried that I'll further damage the engine.

Some background. I have a Gravely ZT XL 48 zero turn mower with a 24 HP Kawasaki twin cylinder engine, model number FR691V-AS08.

Earlier in the season, I noticed a quiet clicking sound coming from cylinder 1. I checked the oil level, noticed it a little low, and added oil to it. The clicking didn't seem to go away, but the clicking didn't seem to bother how it ran. A couple of months later, while mowing, the clicking started getting louder. All of the sudden there was a loud clank and the engine lost nearly all power. I got it back into my garage and removed the valve cover. When I removed the cover, the exhaust valve push rod dropped out on the ground and the rocker and rocker bracket were very loose and the rocker was hanging down. I also saw that the push rod was bent. I checked the inlet valve, and, although the rocker was in place, the gap was pretty big. I decided to remove it and check it's push rod. It was also bent.

I also noticed inside the spring that the exhaust port valve guide was out of place, which I assume caused the rods to become bent. According to Kawasaki, the valve guide is an un-replaceable part, meaning I would have to replace the head. I ordered a new head, push rods, gaskets, and oil seals. I replaced the parts, lapped the valves, set the valve clearance, changed the oil and filter, changed the plugs, and fired it up (the piston looked fine, although it had some carbon on it which I cleaned off). It immediately started.

Although it seems to run fine, I can still hear clicking coming from cylinder 1. I removed the valve cover again to check everything. The rockers were still in place, the valve clearances were good, but still there was clicking (which you can hear at any throttle level). I'm wondering if its something I should worry about; if something else deeper in the engine is damaged, or, like I found on other forums, I should just try a different oil (which I'm not convinced will fix it)?

All of this caused by grass clippings and dirt thrown off the fly wheel completely packed the cooling fins on the cylinder, causing the cylinder to run way hot. All of which was hidden underneath the shroud; I never saw it. I've learned now that you definitely need to periodically remove the shroud and clean out the fins on both cylinders.

I apologize for the long message, but I thought it was necessary to offer as much information I could. If anyone has any ideas, I would greatly appreciate your opinions and assistance.

Many thanks in advance!