What is typical hour mark to require a rebuild on a 502 magnum?? Average cost to do a rebuild? Also, if Im lookin at a used boat with these motors. What should I look for problemwise? Thanks for any help.

I'd go more on leakdown. The top end should be done at the 350/400 mark but if you've got low leakage and an even balance and ther oil pressure is good I wouldn't be worried at all. I might freshen the top end, put a dial indicator on the cam and just keep running it.

Depends on how those engines were driven. Those engines have a thousand potential hours, but not at 5000 rpms. If you are looking at a boat with these motors, should need to take in the whole picture.

Would these motors have been underpowered in this boat? Thus requiring them to have the (rap beat out of them on a regular basis. Does it look like the previous owner took care of them?

These are really the same questions on any used power boat.

What are you looking at buying?

Good luck with your hunting.

If you really are worried, then use the Sunkin technique also.

Whenever I buy a boat, I try to make sure that it is priced ASSUMING that I need a new engine or 2

The current front runner is a 35 Fountain. Its located a couple states away from me so I wanna try to get as much info as possible before I would take a trip to see it. The current motors are listed at about 625 hours. I would definately have a survey done prior to buying any big purchase item.

I appreciate the info guys.

625 is close if not there. You'd have to look at the numbers assuming rebuilds. Maybe not today, but in the very near future

I agree on it's close....but depending on how they were run..I ran a pair of non-magnums over 1000 hours and pulled them apart, looked like they had 100 on them, but they were run fairly easy RPM wise but in a heavy boat and ran royal purple oil for the last 5 years....just no cystal ball yo can peer into..and about the only thing a surveyor can do is a compression test...and from there ????? Rob

The stock valve springs are prone to getting weak at around 300 to 350 hours. When we looked at ours during that time frame everything looked fine but we had lost about 450 rpm on top,,,, valve float according to the engine builder. When you freshen the top end you should go ahead and get a first class valve job with the good parts and if your budget allows go ahead and put in some Crane roller rockers. This gave us the rpm back and only cost about $1800.

And if there is 625 on the motors there will be the same on the drives. I would also be worried about them. just my .02 good luck Jeff

Thats kinda my concern. I know Im not getting a pristine boat for the price. But Im not reallly looking to get a project boat. Id rather spend my money on gas. lol

You could get lucky, you could get crushed. Sometimes there's no way to know.

There's a magic point that the absolute best time to sell a boat occurs. That's the point where it still looks and runs good but it's also fairly close to needing a total refit. At this point, one of three things happens;

1- the boat gets sold;
2- the boat gets a total re-do;
3- the boat begins the beginning of the end- it gets a continual dose of "good enough" patches as it slowly deteroirates into a POS.

#3 often happens right after #1- a bargain shopper gets in over his head and can't afford to do anything the right way.