Engine lifetime
 

Hello

I'm new to this board and have been reading some post to get some knowledge as I am looking into buying a Scarab, Checkmate or similar soon. One thing that wonders me is that most boats seems to have engines that has run not more that 500 hours or has been rebuilt. Is 500 hours what you would expect of a standard mercruiser in the 6-8 liter range before rebuild ? If yes, why is this so ? compared to car engines that seems like a very short lifespan. I understand that the life on the water is a lot more rough that life on the road, but that it should translate into more internal wear ?

Thanks,

Re: Engine lifetime
 

I know of 330's and 365's that have been running since the late 80's without any problems......some people are just lucky! I shoot for 400 hours never seam to get there......

Re: Engine lifetime
 

500 hrs is getting close. Yes there are some with 7-800hrs but that is not the norm.
Compression test will give you an estimate how you're doing.

Re: Engine lifetime
 

I Was Told That 500 Hrs Is A Good Time To Rebuild For A Fairly Stock Motor .on The Other Hand Roller Cam Motors Where 2 The Replace The Lifters And Valve Springs Every 2 Seasons.the Rest Of The Motor Should Be Ok.my Boat Was Purchased In 2001 With 45 Hrs On It And To Date Just Turned 91 Hrs.more Drive Problems Than Motor.

Re: Engine lifetime
 

Thanks for the replies.. which lead me to the conclusion that I should expect to have the engine(s) rebuild soon if I buy a boat with 500 h on them.. Another thing. A boat dealer just told me that Volvo engines should have a lot more hours on them before rebuild than Mercruisers.. any one who can back this statement up ?

Re: Engine lifetime
 

Forget Volvo's. Re-sale will kill you. Dealer is just telling you so he can get rid of it.

Re: Engine lifetime
 

Volvo engines and Mercruiser engines use the same block, they will wear out the same. The life span on a boat motor is shortened because we beat the crap out of them. Just think what would happen if you drove your car like a boat, a wide open up hill full throttle blast from 0-5000 rpms while sucking dirty water thru the block for 1 or 2 days a week and then sitting in 100% humidity for 5 days. Where I live I get to boat like this for 4 months and motor sits the rest of the year (winterized but with open valves). The biggest killer of boat motors in no particular order is:

RPMs
ingesting water, humidity, internal rusting, pitting
overheating
lack of winterizing and regular maintenance

Re: Engine lifetime
 

jhnrckr is right,hook something that tows hard to the back of your car or truck,idle it for a 1/2 hour then floor board it without shifting out of first gear for 10 minutes to 3 hours at a time,you'd almost expect it to blow up after a few times. That 100,000 to 150,000 miles most automotive engines normally last would be more like 2500-5000 miles!!!! Iv'e seen guys with 600 hours on 10 y/0 boat motors but its not the norm,400-500 hours combined idleing/part throtle and w/o operation seems to be the average i hear. The guy's who hold them close to rev limiter 95% of time its more like 150-250 hours,the biggest problem is when someones selling a boat they all claim to have run it like first description!! When Crocket remapped my efi computer last time on dyno,his laptop showed how many hours run time motor actually had (NOT WHAT HOUR METER SHOWED,THEY CAN BE EASILY UNHOOKED!!) and how many hours it had been run in each rpm band (0-2000,2000-3000,3000-4000,4000-5000 etc). I don't know if mercruiser scanner also shows this but it might be worth checking on,there are ALOT of dishonest people who run there boats w/hour meters unplugged! Smitty

Re: Engine lifetime
 

I went 620's on a Merc 454 ;then sold it still ticking. (Back then: Mobil-1 15W-50; need you ask)? It was a company boat and took some abuse I am sure. Just did seasonal oil changes over about 5 years I think. Never a problem.

Re: Engine lifetime
 

Motors should last the same, but the Volvo drive will probably last 3 or 4 times as long! Too bad resale hurts them so bad.