"Roger Long" wrote in news:459ea606$0$18859
:

I've never had the opportunity to see the inside of an abused diesel
cylinder at overhaul

Has nothing to do with boats, but my 1973 Mercedes naturally-aspirated
2.2L 4-stroke 4-cylinder that spent the first 23 years of its life
driving across Charleston City traffic, owned by a retired Navy captain
and his wife, is probably a pretty good example of an abused diesel. 23
years is the point at which I did a 4-hole overhaul on it, somewhere in
the 330,000 mile area, but we're not sure how many times it went around
its 99999 mile odometer before I got it. The Captain couldn't honestly
remember when I bought it from him. It sat idling in the awful city
traffic most of its life before I got it....and since I overhauled it.

One cylinder was lower in compression than the others, so my mechanic,
Stephan Reinhardt, a German who worked at the main engine factory before
coming to the US to start his own Mercedes shop, Star Motor Service,
decided to pull it apart. One of the compression rings was cracked and
he made me a great price on doing a full overhaul, restoring the little
diesel to new condition. I was amazed how little carbon and deposits
were in the cylinders and in the pre-combustion chambers in the head
where the injector and glow plug reside. Every time I run it, I'm still
in awe that the explosion in the pre-combustion chamber flows down the
tiny hole through 5 little ports into the main cylinder without just
blowing it all to hell. You could see the trail of the explosions as
they came out into the cylinder along the head in a 5 pointed star
pattern. I still have a "souvenir piston" of the original 23-year-old
set Stephan presented me, leaving its original piston pin pressed into
one side of the piston, but sticking out so you can see the fine machine
work and quality. The pin has the polish of a fine precision mirror and
you CANNOT run your fingers across its surface and define where the
connecting rod bearing bore the brunt of the blast and moved back and
forth across its surface for 23 years of use. That pin is a true trophy.
The piston top is black, but shows no carbon buildup on it...even not
along the tracks made by the 5 holes blowing out sideways against it
during the "main bang" as it passed TDC...over and over.

The bearings in the bottom were "ok" but I wanted them all replaced.
Stephan started to put the old 23-year-old double-row overhead camshaft
roller chain back against its original tensioning shoe. I said "replace
it, it's old and has gotta be tired by now". Even the shoe, which was a
brown fiber material was just fine! 5 links from that chain were in the
"trophy box". Before his death in a terrible motorcycle accident, he
never let me live down replacing a perfectly good chain...(c;

It sits outside waiting to go any time you're ready. If we're going to
California, I'd like to take it by the shop for an oil change and filter
before we leave. It runs on 20W-50 Rotella T, just like the big boys
rigs. I bought it its 12th monster starting battery 3 weeks ago. Cranks
much easier when all the plates don't have holes in them....(c;

Stick your finger in its exhaust gook and you'll never get it to come
clean. It's always like a greasy lamp black....even before I started
running it on 80% old frying oil and 20% regular gas...which cranks fine
but it hasn't gotten cold in SC at all this year. By Summer, I hope to
be running it on 90/10 with even less thinning gas in it...in the heat.