HP500 Question
 

On average (assuming good maintenance procedures) how many hours could I expect out of a Merc HP500 engine before rebuild time? (38EC)

SR-71

I would assume if they don't have the chit run out of them and were maintained 400 - 500 would be possible. Big thing with the 500's is the valve train maintence, do that and you should be fine. When I rebuilt the 500's in the last boat; due only to the broken spring and dropped valve; the rings, bearings and internals were like new at 170 +/- hours. I only did the whole deal for the peace of mind of knowing they were 100% new and they were already out of the boat. I have a friend that has a '97 35 with 500's and they have close to 400 hours and have only had oil and filters, he broke down last year and did spark plugs. But he does not run the boat very hard.