J: Its very important to 1st remove the sparkplug(s) and crank over the engine to remove any accumulated water . Next spray some wd-40 down the cylinder(s)and again slowly turn over the engine too remove any additional moisture . Next remove the coil and ignition module and any other electrical components and let air dry or put within your oven at around 100 F. for 10 minutes . Finally you should drain the oil from the crankcase and let dry out for a day or so , followed by new oil and filter . You will need to drain the fuel tank and carburator bowl along new spark plugs air filter and fresh fuel and fuel conditioner . Once you get the unit running let it get up to temp and then redrain the crankcase oil and refill . I would then go over all greasable components and inspect and regrease with a lithium or moly based grease . I suppose if you were really picky you could check the wheel bearings also , along with the transmission fluid and the battery since it also could have been contaminated. These are the basic issues that come to mind . Hopefully others will chime in for anything I have missed .

suggest another important area to clean up - electrical system.

Remove batt - have shop to LOAD test - replace if needed. M/W, clean all major elect connections to bright metal (take pix of cluster connections or make diagram of same before taking apart to aid in correct re-assembly). Pay particular attention to chassis ground connections. Be aware of potential problems inside various switches - may need replacing. May also need to remove flywheel to clean alternator components (take care when removing/replacing flywheel and retorque to proper values).

Lawn/garden tractor electrical systems in general are not designed/built to withstand liquid moisture from a flood or even a garden hose/power washer session. Connections will corrode and - over time - can cause a variety of functional problems.

IMO depends on how long it been in the flood and how long it set after the flood????? few Days maybe, month or more IMO froget it. I addition I would use pressure washer and wash it first. This will blow all the mud and crap off.

Now that you got it clean you can get to the represervation. This would be very time comsuming and worthy of the time and effort. Some of the things you may have to take apart and clean; spindles, wheel off the axles, spray all the switched and elect connections with wd40 or something that will displace the water and leave oily film, Carb., ignition, starter, also. gas tank removed and flushed and cleaned along with the hoses to the engine. draining the engine oil IMO may not be enough you would have to flush. First I would put some deisel fuel in the crank case and rock it so it splashes around to wash off internal parts fill with oil hopefully it will start run for 10 mins and drain and refill IMO

The second most important conponent! Transmission. Which IMO will probably the the hardest of all to get the water out. Also you have to ask you self it it worth it??? even with thorough cleanup and flush it still may not start or move and if it does little gremlins playing havoc down the road.

"spray all the switched and elect connections with wd40 or something that will displace the water and leave oily film"

Moser - waste of time, mho. corrosion/rust will already have started at connections. could use wd40 AFTER cleaning connection to bright metal...

Agree on tranny concern.

hmm, there's alot to think about i guess. By the time i buy a new batter, oil, trans fluid, fuel, spark plug, filters and some type of electrical connector cleaner that will be a lot to put into something that may or may not even run. It was sitting in the water for about 24 hours and it's been about a month since it happened so i may just sell it for scrap and put that towards another mower.

Settting for month IMO is the killer. Cylinder/valves or cylinders have already corroded (reaction with Carbon and water turning the carbon to white concrete)and have locked up. Even it you unlock it probably ruint rings IMO.

flood the engine with Marvel Mystery OIL after draining all fluids from everywhere. Refill with fluids and attempt to operate. Fix everything that prevents operation as it arises. You may get a reliable unit very cheap and easy or it will just be a constant struggle.

In my opinion, I would do every thing I could except spend big money. It cost nothing to thoroughly clean the tractor of mud, and the electrical components. After a thorough cleaning inside and out, fresh oil, and fresh gas, etc., I would see if I could start it. While it is possible that it is junk, it is also possible that it can be made useable with a lot of elbow grease, and little money.

To put it another way what have you to loose, if you can get it running for $50 in parts and several hours of time. You could end up with a tractor that would last for years at a minimal cost.