wrote in message
oups.com...

Dream on. The only way to realize 10,000 - 20,000 or even many more
hours from a marine diesel would be to run it almost continuously. The
average intermittent use pleasure boater will be very lucky to get
5,000 hours from a diesel, and even then it will need to be one of the
slower turning models.
You even find some old trawlers with hours up in the 6-7K range, but
10,000 or more is almost unheard of. Cripes, it would take the average
pleasure boater 50-100 years to do 10,000 hours and by that time the
darn thing would simply rust apart. :-)


Chuck,

I realize your post is related to the boating time required to acquire over
10,000 engine hours but, in terms of engine longevity, you might be
interested in the following email response I received from Bob Smith at
American Diesel Corp. American Diesel sells replacement engines and
components and owns the inventory and intellectual property of the former
Leyman Ford.

I had posed a question regarding service life of the Leyman Ford, 120 hp
diesel in Mrs. E's Grand Banks because the engine meter showed 6800 hours.
His response was as follows:

===================================
Dear Richard,

You can expect between 20,000 - 25,000 hours before wear might require
a rebuild. At 6,800 hours it is just starting to run at it's best.
Maintain the bolt on items is the important thing. We have various upgrades
and
improvements for the 120, but you will probably find them already
installed.

What is the boat and owners name? Maybe I know the boat.

We can supply you the latest (current production) Ford engine with all
new marine equipment for about $12,000. Fits in same bolt holes. But
you will not need it.

Check out the transmission. Have oil sample done on the transmission
oil. It is probably a Borg Warner 1013-000-003 CR2 unit.

Best regards,
Bob Smith

================================================== ==========

Although I think he may be a little optimistic, Bob Smith enjoys a excellent
reputation for his knowledge and honesty. I mentioned this to the surveyor
who inspected my wife's boat and is also a Grand Banks owner and he agreed
with what Bob had said.

In my opinion the newer turbocharged diesels that are tweaking lots of
horsepower at high RPM out of small packages have a much shorter service
life. In this case however, the normally aspirated Leyman Ford is physically
almost the same size of the Volvo engines in my Navigator that produce over
three times the hp.

One final note. I have a friend who just completed his first east coast
trip from MA to Florida in his '72 Hat. with normally aspirated DD 671's.
Both engines have well over 10,000 hours as the boat has been regularly used
for fishing. They both run fine, although the port engine has some minor
scouring on one cylinder wall. The diesel mechanic that inspected it told
him not to worry about it, he still had a few thousand hours left before a
rebuild would be required.

Eisboch

On Wednesday 05 January 2005 8:53 am in rec.boats Eisboch wrote:

In my opinion the newer turbocharged diesels that are tweaking lots of
horsepower at high RPM out of small packages have a much shorter service
life. In this case however, the normally aspirated Leyman Ford is
physically almost the same size of the Volvo engines in my Navigator that
produce over three times the hp.

This is correct, wear is caused by friction and friction is
proportional to the square of velocity.

One of the main reasons that diesels last longer is that they
run more slowly, producing max power at around 2000 RPM or less.


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Chuck,

I realize your post is related to the boating time required to acquire over
10,000 engine hours but, in terms of engine longevity, you might be
interested in the following email response I received from Bob Smith at
American Diesel Corp. American Diesel sells replacement engines and
components and owns the inventory and intellectual property of the former
Leyman Ford.

I actually had the Ford Lehman in mind when I noted that some older trawlers
can be found with 6000-7000 hours. Big block per HP to create an ample heat
sink, slow rev, naturally aspirated, etc.

A friend of mine is a marine surveyor, and previously worked as an engineer for
one of the major diesel mfgrs. He is one of the few guys really qualified to do
mechanical and hull surveys at the same time. Jay has told me, (and he recently
wrote a magazine article reiterating the point), that
he is always doing surveys for people who
are buying a used boat with 3,000 - 4,000 hours on a marine diesel. He will say
that most of the buyers are very optimistic that they will get several thousand
more hours of service- even when he finds a few problems or the oil analysis is
very discouraging. The "diesels are immortal"
legend seems to fuel the optimistic fire.
My friend the Perkins dealer reports that
many well-cared-for engines simply wander off to the elephant graveyard before
they ever see 5,000 hours, and the only engines he is familar with that do
10,000 or more are in commercial fishboats, etc.

My previous engine went TU right around 4000 hours. I religiously change the
oil every 50 hours, and almost overmaintain an engine. In my case, it was a
physical failure of a peripheral part, rather than a loss of useable
compression, that caused a hydrolock and sudden failure. It's true that my
engine didn't "wear out", but it was broken beyond practical repair (unless the
Cheap and Dirty crew were hired for the job) in any case.

In about 40-years of servicing marine diesels, the Perkins dealer has arrived
at the conclusion that the most frequent cause of diesel failure in a pleasure
boat is a worn-out oil cooler. (My failure was due to a failed solder joint in
the turbo aftercooler)

The 120HP Lehman was originally conceived as a farm tractor engine, IIRC.
When run almost non-stop, they can last enormous amounts of time. I once saw a
maintenance manual for similar engines used to generate electricity at North
Slope oil field camps. There were a series of maintenance tasks to perform
"every 10,000 hours", and some major refits due
at the 50,000 and 100,000 hour marks.

I have lost track of the source, but there is a chart kicking around that
demonstrates the number of gallons of fuel that can typically be burned in a
diesel cylinder before excessive scoring and ring wear begins. A 6-cylinder
Lehman will burn about 1/3 gallon per cylinder, per hour, at cruising speed. In
6,000 hours, each cylinder will have burned about 2,000 gallons of fuel.
Compare that to some of the higher HP 6-cylinders that burn several gallons per
cylinder, per hour- and it helps to substantiate the observation that the high
revving, light weight, stressed-out "modern" diesels being asked to behave more
like gasoline engines than traditional marine diesels will also behave more
like gasoline engines when it comes to life expectancy.

I remain at odds with the statement that one can routinely nurse a pleasure
boat diesel to the 10,000 or 20,000 hour mark, (the number of years required to
do so notwithstanding). All the miraculous exceptions, and notoriously durable
engines like the small Lehman, simply prove the rule. The 10,000 hour pleasure
service diesel is probably about as rare as the 2700-hour gas engine: I
wouldn't say they don't exist, but neither would I count on typically getting
that sort of service.

"Gould 0738" wrote in message
...

I have lost track of the source, but there is a chart kicking around that
demonstrates the number of gallons of fuel that can typically be burned in
a
diesel cylinder before excessive scoring and ring wear begins. A
6-cylinder
Lehman will burn about 1/3 gallon per cylinder, per hour, at cruising
speed. In
6,000 hours, each cylinder will have burned about 2,000 gallons of fuel.
Compare that to some of the higher HP 6-cylinders that burn several
gallons per
cylinder, per hour- and it helps to substantiate the observation that the
high
revving, light weight, stressed-out "modern" diesels being asked to behave
more
like gasoline engines than traditional marine diesels will also behave
more
like gasoline engines when it comes to life expectancy.

I remain at odds with the statement that one can routinely nurse a
pleasure
boat diesel to the 10,000 or 20,000 hour mark, (the number of years
required to
do so notwithstanding). All the miraculous exceptions, and notoriously
durable
engines like the small Lehman, simply prove the rule. The 10,000 hour
pleasure
service diesel is probably about as rare as the 2700-hour gas engine: I
wouldn't say they don't exist, but neither would I count on typically
getting
that sort of service.

The fuel burned analysis is interesting and, the more I think about it,
makes a lot of sense.
I agree 100% that 10,000 hours or more is optimistic in a marine application
and even Bob Smith was careful to qualify his statement with "failure due to
wear" and advised to watch and maintain the bolt-ons.

Eisboch