We consider the LPW one the Lister "throw-away" engines... lots of problems early in their production life. I think most issues have been solved though. Lister lost their market share (at least in the oilfield) to Isuzu and Kubota and a few others during the early 90's.
These models were used in a number of military applications as well and are just now coming into the marketplace from surplus. There are large numbers of them and the prices have been driven to the basement as a result. Parts are easy to source and not as expensive as most other Lister models.
The LPW will make a fine emergency genset for temporary and fairly short run-times. They are just not quite so great at continuous duty as their predecessors are. The problems generally do not come around for quite a few thousand hours... water pumps recommended at 6,000 hours, typical 10,000 hour decarb - rings and valves. Just general numbers - your results may vary. We saw a lot of them fail at 300 hours in the very early versions.
dieselgman