This sounds majorly wrong - broken in or not, this is roughly
equivalent to 3 or so days of highway driving draining all the
oil from the car - which is well, did I say majorly wrong?

I suspect, while being a total land-lubber, that there is a
universal truth here - used boat salesmen are just nautical
used car salesmen. You mentioned Florida - not that it matters,
but at least there is some press covering Florida and boating
lemon laws - but it's not real encouraging.

http://www.boatus.com/consumer/art3.asp
http://www.findarticles.com/p/articles/mi_m0BQK/is_2_9/ai_114604627

The other universal truth may be this - not any old machine
shop can properly rebuild the MB diesels - in fact, has ANYONE
out there had a positive rebuild experience on one of the
diesel engines? I've heard a ton of scary stories. Is anyone
doing it right?

Best of luck - I'd try the BBB, your attorney, and lots of
letters to any Florida legislators you can think of. The good
news is that you can still find these engines in "gently used"
condition in vehicles that have suffered some degree of body
trauma - so all is not lost.

Conrad

An auto engine will use lube oil when it's driven hard. Automotive
diesels are high speed diesels whereas most marine diesels are
relatively low speed engines due to their constant speed use. Marine use
is substantially different from automotive use - marine use is almost
always constant speed and often at lower than designed engine operating
temperature.

IMHO, this little 76 HP high speed diesel engine should not be run at
constant speed above say 70% or max 75% of its maximum RPM (I don't know
the 240D maximum load rpm, say it's 4,500 rpm) then 70% is 3,150 rpm and
80% is 3,375 rpm.

These engines are designed to run at 80 degrees C. or about 175 degrees
F.; be sure it's running at that temperature.

A compression check will confirm the engine's internal condition better
than anything else short of  disassembly.

New car break in used to be about 2,000 miles of VARIED driving. At say,
a 30 mph average, that's about 67 hours of running, not 10 hours of
marine use.

If it were my engine I'd use Diesel grade SAE 20-50 oil - don't use gas
engine oils.

Have a friend who put a used 4-cyl MB diesel in his 40-ft trimaran and it
worked out beautifully. Only problem was the hardest part to get to on his
installation was the starter. Guess what gave him fits?

Anyway, a rebuilt engine will take some break in but stationary diesels are
broken in running at constant speeds and I'm told this is preferable to
variable rpms. A diesel of any make, certainly one of the bullet-proof
240Ds, should work fine. I'd have the compression checked both "wet" and
"dry". A mechanic will know how to do this on your engine.

On gasoline engines you remove all of the spark plugs and check the
compression of each cylinder. On diesels you remove either the injectors or
glow plugs. After each cylinder has been checked and the psi written down,
do the same again. However, this time put two or three "squirts" of oil in
each cylinder and see if the compression increases measurably. Be sure to
inject oil in the individual cylinder you're getting ready to check, not all
of them at the same time. Doing so will force a lot of the oil out the
injector port.

The reason you do this is that the oil will temporarily seal any leaking
rings and sometimes leaking valves. However, in a rebuild any compression
loss will almost certainly be rings.

As far as engine oil is concerned don't use 20-50 unless it is recommended
for diesels. This is normally reserved for engines with a lot of wear. The
preferred oil is 15-40 such as that offered by Chevron. Although the
viscosity is slightly less when the engine is at operating temperature, it
is designed for more stressful conditions, such as a diesel.

Good luck!

Thanks everyone for the excellent feedback! We did a C-check and discovered
very weak pressures in all cylinders. When we checked blow-by and blocked
off the crankcase vent we got massive oil geyser out of the dipstick tube.
Along with the oil came many small chunks of metal. My guess is that a oil
ring or two gave way. At any rate I am in the market for a reman short
block. Any leads on good sources would be appreciated. Thanks, JAB

there is a 240d motor on e-bay

ngines & Components > Complete Engines
        Mercedes Diesel Motor~150k miles~240D~1975~RUNS~4 cyl    em number:
7966508345   

J.