26sonic

hour wise what maint needs to be done on the merc 525 efi engines?

Crude Intentions

iTrader: (1)

Not sure by maintenance if you mean oil changes or actually going into it. 300 seems to be the numbers people use for top ends. Headers are notorious for problems.

Think this thread will have some 525 info

http://www.offshoreonly.com/forums/g...any-hours.html

Young Performance

If the valve springs haven't been done by 200 hours, then they need to be. They are pretty light springs to begin with. When changing the springs, we also change the retainers, locks and seals. We change out the stock 7* retainers for 10* retainers, which increases the install height by about .100. This allows you to run a much stiffer spring. You also need to check the rocker arms for signs of the poly lock hitting the rocker. If any of the poly locks are rubbing the rocker arm bodies, then it's time to replace them. Obviously, you also need to check the headers and tails.
Let me know if I can help in any way. You may wnat to read that thread as well. There is lots of good info.
Eddie

bajamann

In the process of refreshing my 525's with 300 hours. Springs were shot. Three head gaskets were about to let go. Ordered upgraded parts from Young Performance. Hope to have em running this week. Had I waited much longer I would probably be looking at some serious repairs. Took the opportunity to clean out the cooling system and pressure check the headers. Also did cmi modifications to headers and tails.

VoodooRob

I'm doing exactly the same as bajamann, I'm right at 280 hrs.

imartin

Whats the "CMI modifications to headers and tails"?

Young Performance

Remove the water hose that goes from the rear of the distribution tube to the bottom side of the tail. You can just plug off the holes. That hose will rob water from the header, which is thought to contribute to them cracking.
Eddie