700 Top End rebuild questions
11-18-2011 | 12:39 AM
#21
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From: Denmark and hopefully some place nice
Ok I just got off the phone with Bob from Merc HP on 700 top end recommended preventive maintenance. He said " at 300 hrs. pull valve covers and do valve spring, rocker arm, retainer inspection. Check for broken or damaged valve springs, retainers etc. If all looks good then do a leak down on motor. If leak down is good then run it for another 100 hrs and change the springs at 400 hrs and do another leak down. If leak down is good run it and if leak down is marginal or high do valve job." It only takes a few minutes to call and ask questions. Why would you not want to get the info from the manufacturer ? It doesn't cost anything and might save you a whole lot of money on repairs not needed, but hey I can break anything no matter what they say.
Mercury doesn't tell you everything. 400 hrs on this valve train is very optimistic. There are known rocker arm and spring failures on engines with less than 200 hrs. Drop a valve and the valve springs and rockers will be the least of your worries. Preventative maintenance is the key to not breaking engines!
I'd be very hesitant to follow the description above. As stated by Lifesaboat, if a you dump a valve ect, in vorst case it could seriously damage the engine. The "a little more, a little more and just a little more" approach, is not something I would feel safe running. I also don't really find it to be a very good description of the exact valve train life. I know there are many variables, but still it is somewhat vague.
11-18-2011 | 06:37 AM
#22
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From: clark NJ
If there are known issues with springs and lifters and rockers why not replace them all and be safe not sorry..I know its alot in the beginning but ive learned in the past its always best to do more now than be sorry and puke a engine... Its either pay alittle now or alot later..
11-18-2011 | 07:55 AM
#23
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Joined: Sep 2003
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From: Fort Erie Ontario Canada
Ok I just got off the phone with Bob from Merc HP on 700 top end recommended preventive maintenance. He said " at 300 hrs. pull valve covers and do valve spring, rocker arm, retainer inspection. Check for broken or damaged valve springs, retainers etc. If all looks good then do a leak down on motor. If leak down is good then run it for another 100 hrs and change the springs at 400 hrs and do another leak down. If leak down is good run it and if leak down is marginal or high do valve job." It only takes a few minutes to call and ask questions. Why would you not want to get the info from the manufacturer ? It doesn't cost anything and might save you a whole lot of money on repairs not needed, but hey I can break anything no matter what they say.
11-18-2011 | 11:34 AM
#24
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From: Ft.Lauderdale, Fl.
Mercury doesn't tell you everything. 400 hrs on this valve train is very optimistic. There are known rocker arm and spring failures on engines with less than 200 hrs. Drop a valve and the valve springs and rockers will be the least of your worries. Preventative maintenance is the key to not breaking engines!
11-20-2011 | 07:56 PM
#26
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From: Deatsville, AL
Thats funny, because each of the 3 times i called I got a different answer. Each of which gave me different ideas/suggestions etc. 
Although all 3 said to do a leak down and not to worry till I see like 30%. I have a dealer right now telling me $12K to do both top ends. Is that about right?
The reason I got on this trip is I have 2 friends who just lost a 700 each. Springs/rockers. Nasty damage, but with less than 225 hours.
Although all 3 said to do a leak down and not to worry till I see like 30%. I have a dealer right now telling me $12K to do both top ends. Is that about right?The reason I got on this trip is I have 2 friends who just lost a 700 each. Springs/rockers. Nasty damage, but with less than 225 hours.
