Stephen Trapani wrote in
:

Any ideas?

Stephen



I assume it has a heat exchanger, not raw water cooling. Fill the fresh
water side with coolant. Leave the cap off the fresh water heat exchanger.
Start the engine and idle it until it warms up a little, but not hot. A
little coolant will naturally escape as it expands. Watch the level with
the cap off. See any massive bubbling, indicating there are hot gasses
escaping from the cylinders into the cooling passages in the head and
cylinder walls? This'll tell you if the head is cracked or is warped
enough to let gasses bypass the head gasket into the cooling system. Not
rocket science, but reliable. No computer is necessary...(c;

Also, note if the engine runs smoother with the pressure cap off it.
Sometimes small quantities of pressurized coolant squeeze their way into
the cylinder as it sucks in fresh air, compress and EXPLODE INTO STEAM
inside the cylinder head as the piston comes up over TDC, making a bad
knocking sound, too! Are you losing coolant for no apparent reason? This
may be why if you are.

Flush out the bilge with fresh water after midnight when the greenies
aren't watching to get the little coolant out of the bilge...(c;

No fun....

--
Larry

Larry wrote:

Stephen Trapani wrote in
:


Any ideas?

Stephen




I assume it has a heat exchanger, not raw water cooling.

It's raw water.

Fill the fresh
water side with coolant. Leave the cap off the fresh water heat exchanger.
Start the engine and idle it until it warms up a little, but not hot. A
little coolant will naturally escape as it expands. Watch the level with
the cap off. See any massive bubbling, indicating there are hot gasses
escaping from the cylinders into the cooling passages in the head and
cylinder walls? This'll tell you if the head is cracked or is warped
enough to let gasses bypass the head gasket into the cooling system. Not
rocket science, but reliable. No computer is necessary...(c;

Also, note if the engine runs smoother with the pressure cap off it.
Sometimes small quantities of pressurized coolant squeeze their way into
the cylinder as it sucks in fresh air, compress and EXPLODE INTO STEAM
inside the cylinder head as the piston comes up over TDC, making a bad
knocking sound, too! Are you losing coolant for no apparent reason? This
may be why if you are.

Flush out the bilge with fresh water after midnight when the greenies
aren't watching to get the little coolant out of the bilge...(c;

No fun....



--
Stephen

-------

For any proposition there is always some sufficiently narrow
interpretation of its terms, such that it turns out true, and
some sufficiently wide interpretation such that it turns out
false...concept stretching will refute *any* statement, and will
leave no true statement whatsoever.
-- Imre Lakatos

Stephen Trapani wrote in
:

It's raw water.



Sorry............................Yecch.

--
Larry

Larry wrote:

Stephen Trapani wrote in
:


It's raw water.




Sorry............................Yecch.


Any water passage I've seen in the engine still looks completely uncorroded.

Stephen

Try this:

Get a plastic milk jug, cut it open so you can wipe it clean with a
rag. Put fuel in it. Get some clear tubing from Lowes or Home Depot.
Run the tubing to the fuel fitting on the inlet to your fuel pump.
Fill the tubing with fuel and allow it to siphon the fuel from the milk
jug. Start your engine. If it does not lose power as it did before,
then suspect your fuel filtration.
The Yanmar mechanical fuel pumps seem to go bad all the time. I got an
electrical pump from JC Whitney that I put in series with the
mechanical one. It is wired to the starter so it always provides low
pressure to the engine. It keeps the engine primed.
It sounds like you have both engine timing and fuel problems. Valve
timing is easy to set on this engine. Injection timing is a little
harder but a COMPETENT mechanic can do it. You can do it yourself if
you can follow the directions in the service manual.

For cold starting, use the decompression levers. Relieve compression
on one or both cylinders, get it turning then put in compression, this
will get things lubed well and moving before you are trying to work
against the compression.

You might also check your fuel return line. If it is blocked, you can
have problems. When you are priming the engine, remove it from the
fitting on the injectors, blow into it (a little diesel fuel in your
moth will not hurt you) to see if it is clear.

Take the exhaust hose off the exhaust manifold and run the exhaust into
a 5 gal bucket This will fill your cabin with smoke so be careful but
the idea is to see if your muffler is clogged..

You really need to get a service manual. Try Mastry Marine in St.
Petersburg, FL for it.

Hey, thanks for the advice! A question or two.

wrote:
Try this:

Get a plastic milk jug, cut it open so you can wipe it clean with a
rag. Put fuel in it. Get some clear tubing from Lowes or Home Depot.
Run the tubing to the fuel fitting on the inlet to your fuel pump.
Fill the tubing with fuel and allow it to siphon the fuel from the milk
jug. Start your engine. If it does not lose power as it did before,
then suspect your fuel filtration.
The Yanmar mechanical fuel pumps seem to go bad all the time. I got an
electrical pump from JC Whitney that I put in series with the
mechanical one. It is wired to the starter so it always provides low
pressure to the engine. It keeps the engine primed.
It sounds like you have both engine timing and fuel problems. Valve
timing is easy to set on this engine.

My buddy has a 2QM20 repair manual. It says the valve clearance should
be .15mm. My mechanic guy set it to that. Is that right? where can I get
the setting for the 2QM15?

Injection timing is a little
harder but a COMPETENT mechanic can do it.

We took it in to a shop who set both injectors to 100.

You can do it yourself if
you can follow the directions in the service manual.

For cold starting, use the decompression levers. Relieve compression
on one or both cylinders, get it turning then put in compression, this
will get things lubed well and moving before you are trying to work
against the compression.

You might also check your fuel return line. If it is blocked, you can
have problems. When you are priming the engine, remove it from the
fitting on the injectors, blow into it (a little diesel fuel in your
moth will not hurt you) to see if it is clear.

Take the exhaust hose off the exhaust manifold and run the exhaust into
a 5 gal bucket This will fill your cabin with smoke so be careful but
the idea is to see if your muffler is clogged..


Sorry for the dumb question, but how does this tell me if it's clogged?
Oh, it runs better after I take it off? Why in a bucket? I can see the
exhaust with water coming out below the transom.

Thanks!

--
Stephen

-------


For any proposition there is always some sufficiently narrow
interpretation of its terms, such that it turns out true, and
some sufficiently wide interpretation such that it turns out
false...concept stretching will refute *any* statement, and will
leave no true statement whatsoever.
-- Imre Lakatos