Expected life of Mercruiser 8.1 Horizon

[Rogers]

I am in the market for a '04 - '06 Sun Dancer 340. Seems most if not all of these boats are equipped with gasoline Mercruiser 8.1 Horizon engines. And the model year boats I'm looking at range in engine hours from roughly 300 to roughly 650. Roughly speaking, how many hours can I expect out of these engines before a rebuild or major repair will be needed?
TIA.

 

[Saverio]

If its well taken care of and fresh water cooled you can get anywhere from 800-1300 hours on average for a inboard. not to say people hit over 2k its all on how its taken care of

 

[RollerCoastr]

(oh no, another opportunity to put Rollercoastr on his rant about how useless hour meters are....!)

I have a boat with twin's with under 300 hours. I don't expect the starboard engine to begin this season, not to mention complete the season.

I have another boat, 2 years older with twins with 1,300 hours. They run like new.

Check maintenance records, look for corrosion, check compression, analyze oil and consider the hour meters LAST in your investigation.

 

[Jimmy Buoy]

These engines are really quite advanced in the Marine world. They are "detuned" and capable of much higher hp ratings, but that would reduce their lifespan. Their real achilles heel was the use of aluminum exhaust manifolds, but I think they went cast iron by the year of manufacture that you are looking at. Bottom line as has been said, maintenance is the key. As long as cooling water hasn't been allowed into the exhaust valve area via corroded/leaking manifolds the engine should last 2000hrs or more. Usage plays a part as well and you can have a computer hooked up to the engine and actually see how much of the running time has been used at various rpm ranges. That will tell you if has been abused by the operator.

Great engines with lots of useable torque compared to the 454's + many areas of advancement with engine efficiency and protection too. Good luck!

 

[FootballFan]

If its well taken care of and fresh water cooled you can get anywhere from 800-1300 hours on average for a inboard. not to say people hit over 2k its all on how its taken care of

Agree.

Also if you haven't already, look at the 340 Sundancer threads on this site. Great information.

I used to have a 340 on Lewisville. Fantastic boat.

 

[northern]

Go fast get new engine soon. Go slow last a long time.
We have twin 454 with 2300 hours. Used 1/2 QT every 100 hours. Boat has same power it did when it had 600 hours. We go at 1200 to 1400 RPM 95% of the time. Go fast 454 according to those I know last 1000 hours before they think of replacing them and at 1200 hours they get rebuilt one.

 

[Converse48]

Ask mistercomputerman.

 

[Billfletcher]

There are a lot of people on this board who have them. I don't recall hearing much negative publicity. Our past boat had them and over 3 seasons of fairly heavy use, I had to replace one water pressure sensor. I am not an engine expert, but I don't think there is a better, gas, marine engine out there.

 

[pvan]

A great way to confirm internal health of an engine regardless of hours is by testing both the compression and what is called a leak down test. Marine repair shops charge about $250 per engine for these two tests. Actual hours on the meter is only one part of the puzzle