I know you Fastech guys must know this. I'm looking at a 370SS, 2005, with 525EFImotors. The motors were built 10/2004. They have 375 hours. Fresh water accept for , they said, a poker run in Florida. They have had regular service. Oil changes, water pump stuff. No valve checks. Original headers. What should I worry about with these motors?

Top end service highly recommended at those hours, valve springs by themselves at the bare minimum, leakdown test, etc. Pressure check headers for leaks, this is a must do. Replace impeller and housing a minimum of every year. Pop caps off the heat exchangers and clean out during the season if you do not have strainers. A cool running 525 will keep the header issues at a minimum. If headers have turned colors, they should be a polished stainless, the engine has/is running hot and headers are more likely for trouble.

If it were me, I would be budgeting for a top end overhaul. Much cheaper to do it as preventative maintenance than to wait for failure!

I will also say, a 370 with 525's is a bad azz machine. Hopefully you can make the numbers work and go through the tops. Talk about a sleeper!

Like others have mentioned, the top ends on those motors are due, and the problems involving the Mercury Racing 525EFI CMI Headers are extremely well documented on this site. Do your homework and read about the headaches that those headers can cause... My headers were fresh water use only, and failed a pressure test in 2011 with only 135 hours on them. If you can get the boat cheap enuf and budget for those issues, then the 525EFI's are otherwise a great motor and would certainly kick some cruiser ass in a 370! Good luck!

I agree, a 370 with 525s is rare and would surprise many at the next poker run! Have a survey done and let us know if you pull the trigger, curious on performance numbers.

Hi Guys, Can you please let me know whats the cost of full top end rebuild on these 525efi. Im also looking into one with this set up and 330hours. This would really help me in evaluating the fair price for this boat. Thank you!

Yes I want to know that as well.

I too, would like to hear the performance numbers.

I recently did a rebuild of my 496s (now 525s) in my 2001 370 SS, and I am just now emerging from working on all of the issues (hopefully). I had a bad experience with Raylar rebuilding my engines (maddening), and a really good experience with All American Drive Service (if anyone needs drives rebuilt you really need to talk to George at All American Drive Service - he stands by his product 100% and has helped me out greatly even when I had a drive screwed up by my local mechanic and helped me out personally later when I damaged the drives myself and the insurer refused to pay for new gears).

Regarding the performance, I have my boat loaded with stuff, including an extended swim platform and a couple of paddleboards up front that don't exactly help aerodynamics. I also haven't yet switched the Bravo 3XR 4/3 props , and I have only opened her up a couple of times. Nevertheless, I've seen 55+ mph and think she will hit 60 (maybe even a little higher)without the boards up front. My engines supposedly read about 575-580 hp on the dyno, (but I had a rocker arm break (which Raylar did fix - but left me hanging on the engine removal & shipping fees), then Raylar went out of business, then I found that they hadn't replaced the injectors, a bunch of sensors, etc. that took me a long time to track down). I will do a full write-up on my experience elsewhere.