"akheel" wrote in message
...
FWIW,
I have the same engine and it started to diesel on a trip to Lake Mojave
after always running perfectly. There had been no recent work done on the
engine and I was pretty sure the gas was OK. Well, dummy me was not paying
attention to the temp gauge. When I finally looked down at the gauge, it
was way in the red. At the time I was idling in an inlet waiting for my
wife to back the trailer down the ramp. So I shut it down until my wife
arrived and started it long enough to get the boat on the trailer. I
pulled
the raw water pump apart and sure enough about the half the vanes had come
off the impeller. Replaced the impeller (made sure to remove the T-stat
housing and hunted down all of the little pieces, I hope). The next day
and
thereafter, it ran perfectly. I guess I was lucky. No sign of ill
effects,
such as warped head or other parts, cracked stuff, etc. Moral of the
story:
If it diesels, check your temp and then check your raw water pump; its
real
easy on a Volvo (engine mounted) and always carry a spare impeller(I was
lucky to find one where I was; if anyone needs a Volvo raw water impeller
in or around Bullhead City Arizona, check with Jake's Marine, up the hill
past the turn-off to Katherine's landing). About the only smart thing I
did
that trip was to buy two impellers so I now have a spare. BTW, anyone know
the easiest, least expensive install for a temp alarm on this engine?


"John" wrote in
om:

The two bolts holding the starter to the block actually snapped. There
are no traces of rust on either bolt. The hole to outer most edge of
the block actually had a chunk of the block come off with it, that has
to be welded back on. I do have some experience with older car engines
and understand the basics of dieseling. The boat mechanic mentioned
hydrolock, but at the time the engine wasn't locked. I carry a small
tool kit onboard was able to turn the engine via all of the belt
pulleys a full revolution with a small ratchet wrench. Idle speed per
the tach was about 750-800 rpm. As far as the gas, I've only used
Citgo 89 octane, all from the same station right near where I launch.
The owners manual does specify a minimum of 89 octane. After the
engine shut down, even after dieseling, I never had any problem
starting it, and it didn't diesel every time it shut down which if it
was bad gas I assume it would. I do think the are trying to place the
blame on the gas which would make it a non warranty issue. I also know
once this is resolved I will find another Volvo/Penta repair facility
to take it to

"Rod McInnis" wrote in message
...

"John" wrote in message
. com...
Its in the shop right
now because the starter basically blew off the block a few weeks
ago.

I am having a hard time picturing what happened. The starter ripped
off
the engine?


The
mechanics are telling me there are traces of water in the cylinders
and
that
is what is causing the problem.

Water in the cylinders would certainly make the starter work extra
hard to overcome the added compression. Too much water and the engine
"hydrolocks" and it can't be turned over at all. I would expect such
a problem to
cause
the starter to burn out or struggle, not "blow off the block". If
the starter came loose, then the bolts weren't tight enough!

. Apparently when an engine diesels the pistons go in reverse
which
sucks water in through the exhaust riser (not covered by the
warranty).

That is a common form of "dieseling". It is also possible that
engine continues to "diesel" in the normal rotation. A reverse
direction of dieseling is very short duration as it can't continue to
get a supply of gasoline to keep it going.
If it does run backwards, however, it will definately suck water back
up
the
exhaust. This is very, very bad! Cold water hitting hot exhaust
valves
and
pistons can cause things to crack. Water left in the cylinders will
make
it
harder (maybe even impossible) to start the next time.


When
I asked what cause the dieseling, they said probably bad gas (water
in
the
gas).

Not water in the gas. Too low of an ocatne gas yes. Check the
owners manual on the engine and see what octane rating it requires.
I wouldn't expect a 4.3 L to require high octane gas, but I could be
surprised.

Talking to a car mechanic, he said the primary causes of dieseling
are incorrect timing, of the carburetor being set too rich or lean.

Not too rich, but too lean for sure. I would be surprised, however,
if
your
carburetor had an adjustment for the main jet mixture.

An engine diesels because the temperature inside the cylinder is too
hot. You can have this condition even if the engine isn't
overheating. The timing being off is a good possibility. Another
possibility is that a
vacuum
leak is causing the mixture to lean out.

This hit me
funny because this same dealership did a 50 hour tune up on the
boat in November. I have maybe 20 - 40 hours on it since the tune
up.


Well, it may be too late now, but I would have taken the boat back to
the dealer the first time it dieseled and make them fix it! To have
an engine diesel after a tune up means that they did something wrong!
If your
dealer
is trying to duck the issue and blame other things then I would find
a new dealer!

They could argue that water in the cylinders isn't covered, but I
would argue back that the water got their because they screwed up the
engine and caused it to diesel. Their fault.


Rod McInnis









West Marine sells a temp alarm kit. Or make your own, with a overtemp idiot
light sender from any autoparts store and a light and alarm.
Bill