In article ,
Stephen Trapani wrote:

Jere Lull wrote:

The hard starts could also be from undersized battery or cables,

Yes, I have a low battery bank. Old batteries and it turns over
fairly slowly. Once the engine is warm, it starts in a second or two
every time.

Work on that in any case. I would make sure the battery was well
charged and the connections clean and tight before at least one cold
start, to eliminate (or confirm) the starting circuit as a problem.

A warm engine will usually start more easily than a cold one, and a low
battery's charge will improve quickly. Thus, an easy warm start doesn't
help diagnose the problem much.

The drastic power decrease after a few minutes could be a
mostly-blocked fuel filter, fuel tank pickup or vent. Change
filters, clean the bowls and see if it still happens.

I did this all once. Maybe the Racor needs changing? I had the tank
all the way out and cleaned by two mechanic friends.

The one time I had critter problems, it didn't clear up until I'd
changed the filter twice and brushed off my last one once or twice.
Even then, we couldn't pull full power until we'd motored a few hours at
low power. Lots of critter corpses fell to the bottom of the bowl as
we slowly bounced along.

I'd also suspect overheating at full power, except that the alarms
aren't going off. Any change in the reservoir level, day to day?

Reservoir?

Sorry, I forgot that the 2QM15 was raw-water. I was trying to
figure out whether you might be overheating without the alarm going
off. You have water coming out the exhaust from your other posts,
so I tend to assume you aren't overheating in 10 minutes. Any sign/smell
of overheating as you lose power? Any little things that might not seem
important?

If those steps don't solve it, I'm afraid you're looking at a
rebuild, but don't start worrying until you've exhausted
alternatives, as that's a remarkable engine from what I've heard.

Would a diesel needing a rebuild run hard for ten minutes, then lose
RPM and pushing power?

I don't believe so. Most of the time, they seem to get cranky about
everything.

What you're describing sounds consistent and repeatable. What happens if
you're not pulling high power? Do you have a drop-off if you motor at
200, 400, ... fewer RPMs? If you do, does it take longer?

And about that drop-off: Does the engine die, or will it continue to run
at the lower power for a long time? How high is that lower power? For
that matter, what are the RPMs at high power?

As I write, I also wonder: Is the stuffing box hot when you get the
drop-off?

I still primarily suspect fuel delivery. If it's not the filter, than
possibly something that's binding when the engine gets up to operating
temperature.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
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