A friend of mine had a similar problem on his motorsailor. He had overheating
problems, so took it to the mechanics at the yard in Key Largo for its usual
bottom job and the motor work. Cored out the heat exchanger, ran through the
whole water system (has a trans cooler in line as well) and dropped it back in
the water. Ran great, great water flow at the dock, so we took it out. About a
mile out, overheating! No water. Back in, check everything again. Ran it at the
dock, great flow, put a load on it, great flow, ran for about half an hour at
cruising rpm with load, great flow. Took it back out - lasted a mile.... back
in again.
It turned out that there was a small air leak in the raw water strainer, as Bob
said. Why it would run at the dock and be OK, and not at the same rpm out in
the ocean is still a mystery, but my friend (after blowing a good sailing week)
decided a new water straining system with better gasket sealing was in order.
All is well.
Gary
----- Original Message -----
From: Robert Abbott
To: Dennis C. ; cnc-list@cnc-list.com
Sent: Thursday, May 23, 2013 10:56 PM
Subject: Stus-List Overheating 3GMD - the plot thickens
Don:
One more thing to check.....check to see that your 'o-ring seal' on your raw
water strainer is tight .....if it isn't, your water cooling system will suck
in air and not enough water to cool your engine.
If you take the top off the strainer out to clean it, you might not have put
it back together tight enough. How do I know this? Daa!
Bob Abbott
AZURA
C&C 32 - 84
Halifax, N.S.
On 2013/05/23 11:13 PM, Dennis C. wrote:
Good suggestion from Rich. Even a new impeller can spin.
Also, there may be a suction leak on the intake side of the pump.
Disconnect the discharge at the pump. Start the engine and check for flow
there. (It won't hurt the engine to run a couple minutes with no water flow.)
Try to stop the flow by blocking the hose with a rag or your hand. If the flow
and pressure are good, move downstream. If no flow or you can stop the flow
then the issue is the pump or ahead of the pump.
If the flow is good, disconnect the hose to the little elbow you cleaned.
Check for flow and pressure there.
Dennis C.
Touche' 35-1 #83
Mandeville, LA
--------------------------------------------------------------------------
From: Knowles Rich <r...@sailpower.ca>
To: "cnc-list@cnc-list.com" <cnc-list@cnc-list.com>
Sent: Thursday, May 23, 2013 8:35 PM
Subject: Re: Stus-List Overheating 3GMD - the plot thickens
Suggest checking the raw water pump impellor to make sure the bronze
insert is not spinning inside the rubber impellor. This can happen with a new
or old unit and can fool you in an inspection as the rubber vanes may look
perfect.
Rich Knowles
Indigo. LF38
Halifax
On 2013-05-23, at 22:00, "Don Jonsson" <dbjons...@shaw.ca> wrote:
Hi
I had previously sent out a message about an overheating diesel. The
culprit, so I thought, was the knuckle going into the mixing elbow, because
generally when I cleaned it, it worked again. For a while.
So I finally took of the mixing elbow and gave everything a proper
cleaning. I checked the water pump. I checked all hoses by blowing through
them and the engine.
I put it all back together and it all worked and water pumped like it is
supposed to, except the water pump leaked a bit - needed a new gasket, but I
knew that and just wanted to see if it would work. Got a new gasket and put it
on. Started up and no water.
I took out the thermostat and checked to see it worked - slightly
corroded but it worked, i.e. opened in hot water. Put everything back together
and started it up and a bit of water but too much steam. Took the thermostat
out and put it in more carefully. Tried again, water running, no steam
everything is perfect. Ran it for a while just to be sure.
Turned it off. Waited a while (an hour) and started it up again. No
water.
So the problem is not the mixing elbow (and likely never was as it wasn't
that bad). Not the pump as it looks fine. Not the thermostat - I don't think
although I will replace it.
The problem is sometimes the engine pumps water and sometimes not. And
I'm stumped.
This is a raw water cooled engine which makes things different. Has
anyone had a similar problem and ideas for a solution.
Also, it seems hard to get part numbers for a 3GMD and the local mechanic
had to go find an old book. Is there any place online to find part numbers for
that engine?
Thanks to anyone that can help.
Don
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