CD Power boat engine over heating

[C. Novak]

CD 28 Open Sport Fisherman with over heating Chrysler gas engine. Symptoms, warm up engine at mooring, at low RPM when leaving harbor, temperature guage in "low green," increase speed to 2800 RPMs for ten minutes, temp guage moves to "mid green," reduce RPMs to 1000 and temp guage goes into "Red." All suggestions on fixing this problem will be greatly appreciated.

[Walt Bilofsky]

Look at the cooling water discharge and see how much water you're discharging at various speeds - that should let you know if the problem is raw water flow or something further down the line. If it's raw water, the first places to look are the strainer and the impeller.

Check the coolant level. Are any of the cooling system pumps belt driven? If so, check the condition and tension of the belt.

- Walt Bilofsky

CD 28 Open Sport Fisherman with over heating Chrysler gas engine. Symptoms, warm up engine at mooring, at low RPM when leaving harbor, temperature guage in "low green," increase speed to 2800 RPMs for ten minutes, temp guage moves to "mid green," reduce RPMs to 1000 and temp guage goes into "Red." All suggestions on fixing this problem will be greatly appreciated.

bilofsky@toolworks.com

[Bob Davee]

Is this an old problem or a new one? Some early models CD28 Power had the raw water intake too far forward so that it nearly came out of water at high speed (bow up). I know of one boat where the intake had to be moved sternward into more reliable water. If not this problem then I agree with Walt's suggestions.

Bob
CD 28 Open Sport Fisherman with over heating Chrysler gas engine. Symptoms, warm up engine at mooring, at low RPM when leaving harbor, temperature guage in "low green," increase speed to 2800 RPMs for ten minutes, temp guage moves to "mid green," reduce RPMs to 1000 and temp guage goes into "Red." All suggestions on fixing this problem will be greatly appreciated.



builder@midcoast.com

[Tony Raymond]

If you want to "shotgun" this, My guess would be the raw water circuit. The temp is ok with the rpms up because there is more water getting through. When the rpms are dropped after heating the block,there is not enough water getting through to pull the heat out.
My order of checking would be 1. the belt driving the raw water pump 2. the raw water strainer, 3. the water inlet, 4. the raw water pump impeller.

My money is on the impeller because the problem is rpm related and is also has the highest failure rate amoung the components of the cooling system. Check the belt, strainer and inlet first because they are easier.

I hope it helps. You may have to drop back and go through the raw water and then the fresh water circuits piece by piece until you find the problem. I can't help with much more specifics as I'm a Diesel guy and have never worked on that engine.

Good Luck
Tony



Tonyraymond@digital.com

[Lonnie Sigworth]

I have a boat brokerage business and one of my customers has
a 28' CD that had a Chrysler gas engine. He was having exactly the
same problem. Changes water pumps, cleaned raw water intake filter,
repalced hoses ect. Finally it turned out the heat exchanger was full
of trash reducing the water flow at higher speeds. Cleaned and that
problem was solved. However, he later replaced the gas with Cummings diesel and WHAT A DIFFERENCE !!!!!!
Hope this is of help.........LONNIE

CD 28 Open Sport Fisherman with over heating Chrysler gas engine. Symptoms, warm up engine at mooring, at low RPM when leaving harbor, temperature guage in "low green," increase speed to 2800 RPMs for ten minutes, temp guage moves to "mid green," reduce RPMs to 1000 and temp guage goes into "Red." All suggestions on fixing this problem will be greatly appreciated.

GCYB@worldnet.att.net

[C. Novak]

Thanks to everyone who offered suggestions, I really appreciate it. Hopefully I can get the problem resolved prior to launching this Spring. Chris