hustlerguy

I have a newly purchased boat with staggered merc 700's about 190-195 hrs on them, smartcraft shows over 100 hrs below 1500 and less than 2.5 hrs above 3500 rpm. Did leakdowns on motors came out good, Pressure checked headers and thats all good.
What can some of you tell me about your experience with these motors as far as reliability, attention needed, valve train lasting, misc. other things to watch and what kind of rebuild times are most seeing and expecting.
Are the week links on these motors the valve train (rocker arms, valve springs) or??
I assume the bottom ends are pretty well built for this kind of HP range?

Pismo10

Since it is all about how they were driven, it seems this boat was driven very gently. If 125 hours were above 5000rpm, that would be a different story. Bottom are great I am sure, valve train will be the issue but not yet. Great find.

39 Unlimited

Mercury Racing suggested the rebuild is same as the 525. If engine is 2010 or newer (better rockers) your good for 350 hrs. After that I would do springs and rockers. As long as you follow the maintenance schedule (including using Kendall GT-1 20/50 no exceptions period) you're good for 500 hrs.

I have a 2011 Cigarette 39 Top Gun w/700's - zero problems. The Mercury 700 package is awesome, you'll love it.

SkiDoc

iTrader: (4)

[ATTACH=CONFIG]534619[/ATTACH][ATTACH=CONFIG]534620[/ATTACH]39 I can't remember, did you replace the original Merc headers? I have a new to me boat with 2007 137 hr 700SCI's and I am contemplating just replacing the headers so I don't have to worry about it. I have not pressure checked them yet......They are in cat and not long tails, freshwater.

39 Unlimited

I did not replace the headers. Sent port side (staggered) back to CMI at 150 hrs they said header was perfect, polished and sent it back. If you don't run in salt water and engine has new style CMI's (see below) your in good shape. If your headers have a slight brown tint to them I would replace. This generally means they got hot which tends to make them brittle.

SkiDoc

iTrader: (4)

[ATTACH=CONFIG]534622[/ATTACH]
I[ATTACH=CONFIG]534622[/ATTACH]
I think these may be the newer style. I noticed one on the starboard side of starboard engine is discolored. Newer style or not

F-2 Speedy

iTrader: (6)

Yes, they are the newer style

39 Unlimited

Yes sir they are the newer style. Some discoloration will happen, generally this happens at the top of the headers not by the head. When they get a brown/purple look, time to send back to CMI. They can test and polish back to new. Great people to work with.

SkiDoc

iTrader: (4)

Thanks for the information. What kind of spark plug socket do you guys use to pull the plugs? I tried my Craftsman and the O.D. of the socket would not fit in the head recess. I thought I might just take it to the grinder?

Kelly O

Seems like I just grab a 5/8" 12 point deep well socket.