Re: Universal 5424 Diesel
Gee, for a 33 year old boat, 2,440 hours doesn't seem very high...maybe even a little light? 2440/33=75 hours per year, huh? Check to make sure the hourmeter is actually working. Realistically at that age the kind of use it's received is probably way more important than the number of hours...how does it look? Original or sixth owner? Decent engine maintenance logs or none? I have a 5444 with over 3,000 hours, and just finished redoing the cylinder head, replacing the "water flange" that the thermostat sits in, overhauling the heat exchanger, and replacing the gauges in my instrument panel.
I think the Kubota's are good little engines, and the Universal marinization bits seem okay too. That said, you have to be ready to do a little detective work figuring out the Universal/Kubota parts cross reference - search Google for "Kubota parts" and you'll get a bunch of hits (Kumar Brothers sells a lot of aftermarket stuff). Shops & mechanics used to working on Yanmars, Perkins and Volvos may not be enthusiastic to work on it, but they are pretty simple engines. How much of a DIY'er are you? I replaced three gauges in my panel with nice new Teleflex gauges that are nicer than the originals for $160, and it took maybe a day all told, including changing a bit of wiring.
One thing I learned is that compression and leakdown tests can tell you a lot. OTOH, my understanding is that the real value of oil analysis is tracking changes, so a one time test isn't all that informative. SOME of the marinization parts on these engines are getting pretty scarce (like exhaust manifolds), and even finding these parts used can be tough, but I think most things could be MacGyvered. Good luck!