I have a TS100 with an Alamo boom mower and about 1200 hours on it. It's an open station so I wear hearing protectors. This summer while mowing, I adjusted my hearing protectors and noticed the engine had a pretty loud rattle. Shut it off, checked the water pump, checked the drive to the front-mounted engine-driven hydraulic pump and all was good. Started it a couple weeks later and same issue. Went back several weeks after that and the engine wouldn't turn either direction when putting a pipe wrench on the front pump driveshaft. Finally got around to looking at it more today, and after a good tug on the pump shaft the engine turned backwards but will only go 3/4 turn before it sounds like something hits inside the engine. I can turn it now the same 3/4 turn before it stops. I can't believe it is an internal failure as it was running fine (other than the rattle) the last time we ran it. Pulled the starter and no issues with the starter drive. I read that a leaky injector could cause an engine to rattle due to preignition, but is it possible it could leak enough while sitting to hydrolock the engine? I find it hard to believe it could leak that much through the injection pump, especially with the fuel tank mounted low but figured I'd ask. Next step I guess is to pull the injectors, but even that is quite a project since the mower blocks most of the access to the engine.