525 EFI question?
 

Okay:

I have a single 525 EFI with about 300 hours on the engine and drive. Everything seems to run fine, with the exception of some minor part failures. At what point should I start thinking about doing something before something happens? And what should that something be?
Thanks in advance for the response(s).

Ron

Hey Ron -

I'm sure some more experienced Merc guys will chime in, but I would recommend at least a top end rebuild by now, springs and the valve train are really the only thing that should need to be addressed.

A leak down and compression check should give you an indication of the health of the engine.

Better to do the heads now than loose a spring or retianer and drop a valve. Cheap insurance.

Have a great weekend,

Kirk

Sounds like good advice to me.

Agreed also. Spend 2 grand soon to avoid a major failure later. Valve job, springs and lifters.

kirk hit the nail on the head ha ha no seriosly thats what i would do

Couln't agree more!

Ray @ Raylar

YUP, good advice!:D

Leak down & new headers.

LS

Thanks Guys...appreciate all your help. I'll get right on it.

Ron

Okay: I had a faulty crank shaft sensor and had a throttle response adjusted. Now I can't seem to get the RPM's to 5250with my 24 B1 prop where I used to almost hit the rev limiter with it before. Any quick thoughts?

Ron

throttle responce adjusted?

Have you touched the cables lately?

Make sure you are getting WOT.

Second would be make sure its the correct sensor, and check timing.

Use a scanner to check for active codes that would limit rpms and power. sounds like a reduction to 90% power level on the Guradian protection?

Good Luck,
Ray @ Raylar

Quick question on the top end rebuild that everyone suggested....should the actaul valves themselves be replaced? Does this tend to be a weak spot for the 525 as well (the valves)? What about the piston rings? When is it a good time to swap those out?

New headers??

Yes, the CMIs will likely develop a leak sometime shortly after 300 hours.

it has always been told to me that the top ends should be gone through every 2-250 hrs, headers POSSIBLY around the 350 hour mark and complete rebuild around the 450 hr mark...sound bout correct ? OF COURSE IT ALL DEPENDS ON HOW ITS BEEN MAINTAINED, AND IN WHAT CONDITIONS ITS BEEN USED etc...

How hard do you run it? A fixed number of hours until rebuild without knowing how hard it is run and in what size boat is tough to call. A 525 in a Donzi 22 that runs 95% of its life under 3000rpm will live more than twice as long as one in a heavy 30 footer driven full blast all the time.

Thanks for all your help guys. I ended up rebuilding my engine and it runs like a charm. I thought it was a wiser way to spend money. Unfortunately, I have to sell her now, so if anyone knows someone interested, please send them my way.

You guys were right on about everything. Hopefully, other people that have 525's will do the smartest thing as time goes on.

Thanks,

Ron

Another question...does it matter what type of coolant I use? I'm just looking to top off what is in there already.

Was told that I shouldn't use green colored coolant...?