hours?

Some 120 Lehmans are equipped with rather strange exhaust systems, and
some of these systems can allow water to run back into the exhaust
manifold and into a cylinder if the interior components of the riser
muffler, water-jacketed elbow, etc. rust out or develop leaks.  So that
could be one cause of the early demise of a Lehman.

Lehmans are pretty low-tech, low-performance engines.  I'm told by
people who know a lot about these things that an engine like a Lehman is
happiest running along at 1,500 to 1,800 rpm.  Running them consistently
at higher rpms can accelerate wear fairly dramatically (I'm told) and
will subject the engine to higher heat levels than the components,
gaskets, etc. really like.  This is one reason the engine proved
unsuitable for its original intent, which was heavy-duty truck use in
the 1950s.  The engine is strong and (for its day) very reliable, but it
didn't do well under the higher power and rpm loads required for hauling
semi-trailers and heavy loads on the highway (remember, in the 1950s,
semi-trailers were not very big).  Plus the power output of the engine
was not really sufficient for this kind of work, especially as road
speeds and truck weights began to go up dramatically.

Where the engine proved very successful was in relatively low-power,
constant-rpm applications.  So the Lehman (called the Dorsett by the
manufacturer, Ford of England), proved extremely well suited for
tractors, generators, cranes, and other industrial applications.  The
demands of a marine diesel, at least in the 1960s and 70s, were similar,
which is why the Dorsett was so successful in its Lehman
marine-conversion form.

BUT... if an owner today is in more of a hurry than his 1960 counterpart
and consistently runs his Lehman-equipped boat at higher power settings,
say 2,000 rpm and above, this could take a toll on the longevity of the
engine, particularly if it develops a problem with the raw water or
coolant circulation systems.

Also....the 120 Lehman's Simms injector pump is separately lubricated--
it has its own little oil sump.  Because of the possibility of oil
dilution from fuel leaking past the injector pump pistons, it's VERY
important that the oil in the pump be changed every 50 hours.  As the
oil dilutes, its lubricating properties are reduced, and wear on the
pump's components goes up.  I know, there are people who say, "I change
the pump oil every 200 hours or 500 hours and I've never had a problem
since Moses did his thing with the Red Sea."  Well, they've been REALLY
lucky.  Not only does the operation manual stress the importance of
changing the pump oil every 50 hours, but so do people like Bob Smith at
American Diesel, who probably knows more about the care and feeding of
Lehmans than anyone else around today.  I'm told that the injector pump
is the single most expensive and critical item on the engine.  If wear
or mis-adjustment causes the pump timing to be off, this can result in
Bad Things happening inside the cylinders, which in turn can affect the
heat being developed as well as the buildup of deposits on valves,
pistons, etc.  So if the injector pump on the engine you're inquiring
about is bad, this could cause problems that eventually require an
overhaul.

And...the valves on a 120 Lehman require adjustment periodically.  Here
the operator's manual and the opinion of experienced mechanics can
differ.  I believe the manual wants the valves adjusted every 200 hours,
or perhaps it's 500 hours.  But I recall Bob telling me that the valves
shouldn't need to be adjusted but every 2,000 hours (don't quote me on
that, I may be mis-remembering his figure, so check with him).  So it's
possible that one or more valves on the engine in question drifted out
of adjustment but the valve clearances were never checked.  If the
clearance opens up, the result will be that the pushrod follower will
start hammering on the cam lobe and gradually flatten it down to the
point where it's no longer possible to adjust the valve clearance to
specifications.  The cure is to replace the camshaft or chrome it back
to tolerance if that's even possible, both of which require taking it
out.  If the clearance tightness up (usually not likely), the result
will be the valve can't close all the way, which in the case of an
exhaust valve will burn it sooner rather than later, and in the case of
an intake valve will result in poor compression and incomplete ignition
of the fuel/air charge.  The cure is to overhaul the head to replace the
burned valves.

One other possibility is that the hour meters were replaced at some
point for some reason, so the total number of hours on the engine is
actually greater than 855.  The meters on our boat, for example, were
replaced when the engines had about 1,200 hours on them.  So when we
bought the boat, the meters showed about 250 hours.  I was skeptical of
the 1,200 hour claim on a 25-year old boat, but when I divided the total
nautical mile readout on the boat's original knotmeter (a figure that
could not be reset other than by taking the instrument apart) by the
average speed of the boat, the result was close enough to 1,200 hours to
make that figure believable.  That and the fact that the boat had spent
all its 25 years in San Francisco Bay, where I'm told by boaters from
there that the relatively short cruise distances can easily result in an
old boat having fairly low engine hours even when the boat is used
regularly.

C. Marin Faure
GB36-403 "La Perouse"
Bellingham, Washington

From: "Ron Rogers" rcrogers6@comcast.net
To: "Faure, Marin" marin.faure@boeing.com;

Well there must be something wrong with my Ford Lehman. I bought the boat
new in 1981 and I still have her and the damn Ford Lehman just keeps on
running just like the Energizer Bunny. Yea I change the oil and make sure
the fuel is clean and I even change the injector oil for the winter lay-up
not quite sure this qualifies for high maintenance. I've even run the boat
above 2000 rpms too. Even if I could put four engines in my boat, I'd still
probably only go a couple of knots faster maybe, but I'd sure burn alot more
fuel.
And I'm not sure I understand how a Ford Lehman is the cause of a boat being
badly rolled by passing powerboats? The Ford Lehman is like any other
engine, you take care of it and it will always bring you back to port.
Maybe I'm spending to much time up here in Maine, AYUP!
Mike Gladwin
S. Bristol ME

When I took Bob Smith's diesel class, he said to adjust the valve clearance
between 500 and 1000 hrs. For a 120, you need to retorque the head bolts in
a specific pattern as well. I'm sure if you call American Diesel, they'll
send you the pattern and torque specifications, if they're not in the 120
manual.

Keith
__
Backup not found. [A]bort, [R]etry, [P]anic...
----- Original Message -----
From: "Faure, Marin" marin.faure@boeing.com

Ron et al,

As a former owner of a KK42, let me throw in my 2 cents.  Firstly, without
a significant current boost, a KK42 will never see 10 kts.  The hull speed
is around 8.6 kts and even at that speed the stern is squatting.  While the
KK42 hull does provide good form stabilization, this is not dependent on
going as fast as you can.  We were always comfortable in ours, even without
stabilizers, unless some unthinking cowboys blew past us too close and/or
too fast.

On the Ford Lehman engine - given that there are thousands of these engines
pushing trawlers all over the world, I think that you will find that most
owners feel that they have a die hard, true friend powering away down in
the engine room.  These things run forever with just basic care.  Add to
that the excellent support provided by American Diesel and you have a
package that allows you to cruise world wide with confidence.

John Tegtmeyer

At 09:53 PM 3/12/2004 -0500, you wrote:

John Tegtmeyer jet2@principia.edu
At 09:57 AM 3/13/04 -0500, you wrote:

Another 2 cents.
The Non Turbo Lehman is pretty reliable. The comments posted by others are
pretty right in that the engines require a fair amount of maintenance. I
might add that the raw water pumps are prone to bearing failure. Carry a
spare pump, not just the impeller.

The one major source of serious damage to these engines has not been
mentioned. There is a petcock at the front end of the engine, located over
the exhaust manifold. This is located at the high end of the engine and is
intended for bleeding. I think the air bleeding has been mentioned. What
has not been mentioned is that the bleeding is intended to prevent an air
bubble from forming behind the last cylinder, number 6. If you leave air
there it will create a hot spot. In itself this may or may not cause any
damage, but if you overheat the engine generally while there is a air
pocket behind number 6, you will almost certainly damage the head and
block. The damage may not be apparent at the time. But, the head will most
likely be warped and pretty soon you will be headed for a major rebuild.

It only takes ONE single instance of this and the cost to repair is on the
order of thousands of dollars.

Mike

Capt. Mike Maurice
Wilsonville, Oregon (Portland).