RCE wrote:
wrote in message
ps.com...


Sounds like you've been reading David Pascoe's website. He places the
life expectancy of most diesel engines somewhere near 1,000 hours,
IIRC. We need to get the word out to thousands of people well beyond
1500 hours on their Yanmars that they are overdue for a major overhaul.
I do agree that these engines are unlikely to ever see the 5000 or 6000
hours often achieved with older, lower RPM engines like a Ford Lehman,
my original Perkins (that died only due to a manifold failure around
4000 hours), etc. But to predict they won't even survive as long as a
well maintained marinized automobile gas engine is far too negative,
IMO. Did you know that Yanmar scored better than Volvo, Perkins, and
some other top names in a survey of actual diesel engine owners in the
Jan 2006 issue of Cruising World?


I think (simply my opinion) that a modern diesel boat engine's lifespan is
inversely proportional to it's horsepower. I know a guy that's been through
3 engine rebuilds or replacements of both Yanmar 600 hp engines on his boat
in 6 years. He did a lot of fishing trips and never got much over 1000 hours
on any of them.

RCE

I wish I could recall where to find it, but there has been a study
conducted and a theory advanced that there's a direct relationship
between the amount of fuel a diesel engine consumes and its life
expectancy. The theory bases life expectancy on gallons consumed,
rather than on hours operated. Under such a premise, any fuel
consumption chart for a high HP diesel engine will reveal just how
costly pushing the engine beyond
the most efficient point in the curve can be, in terms of engine life
expectancy as well as the fuel bill. I wonder what your acquaintance's
experience would have been at just a few hundred RPM slower, where his
fuel consumption might have been substantially less. If he's wearing
out a diesel in 1000 hours, he's got the wrong engines for his
application or he's pushing them way too hard, IMO.

Relevant aside: I was just aboard a new Silverton with Yanmars, and
learned that the factory *recommends* that the engines be cruised at
within 200 RPM of WOT and *recommends* that they run totally wide open
for up to 30% of total operating time.
Interesting recommendations, to say the least.