Help Please!!!

[Bill]

Well folks I have a question for you. In september I posted a note about the odds of a piece of debre blocking the intake for my 1GM cooling. The engine had overheated and everything looked to be in order below decks (impeller et al..) After letting it cool down, I ran it for 20-30 minutes without a problem. The consceince of this august body was that yes indeed it had probably just been temperorily blocked!

Today, (winds 20-25, temp 73) i had the same thing occur. After thinking it over, I realized that on both occasions the wind was piping up (20-25) and the waves (seas for inland lake) were from the stearn quarter.

Is there any way that the waves/seas could be blocking the exhaust (most of the time it is under water while under cruising power)? After I allowed teh engine to cool, it ran fine all the way back to the slip!!!

BTW, the engine has been run regularily since september, and probably under the same conditions as today. I cant fingure this one out!!!!

Help

Bill
S/V Rhapsody
CD25D # 148



cd25d@clnk.com

[Captian Mike]

Dear Bill: I talk to a gentleman who owned a CD28 who experienced a similiar problem. He believed the caused of his dilemia was when motor sailing the heel of the boat prevents the oil pickup in the oil pan from being submersed in oil. You may be heel over preventing the oil pickup an thus overheating the engine. The conditions that you described may produce this result. : Well folks I have a question for you. In september I posted a note about the odds of a piece of debre blocking the intake for my 1GM cooling. The engine had overheated and everything looked to be in order below decks (impeller et al..) After letting it cool down, I ran it for 20-30 minutes without a problem. The consceince of this august body was that yes indeed it had probably just been temperorily blocked!

Today, (winds 20-25, temp 73) i had the same thing occur. After thinking it over, I realized that on both occasions the wind was piping up (20-25) and the waves (seas for inland lake) were from the stearn quarter.

Is there any way that the waves/seas could be blocking the exhaust (most of the time it is under water while under cruising power)? After I allowed teh engine to cool, it ran fine all the way back to the slip!!!

BTW, the engine has been run regularily since september, and probably under the same conditions as today. I cant fingure this one out!!!!

Help

Bill
S/V Rhapsody
CD25D # 148

mattngly@concentric.net

[Bill]

Dont think so, I was under power both times. No sail! Only windage on bare poles so not that much heel!

BS

Dear Bill: I talk to a gentleman who owned a CD28 who experienced a similiar problem. He believed the caused of his dilemia was when motor sailing the heel of the boat prevents the oil pickup in the oil pan from being submersed in oil. You may be heel over preventing the oil pickup an thus overheating the engine. The conditions that you described may produce this result. : Well folks I have a question for you. In september I posted a note about the odds of a piece of debre blocking the intake for my 1GM cooling. The engine had overheated and everything looked to be in order below decks (impeller et al..) After letting it cool down, I ran it for 20-30 minutes without a problem. The consceince of this august body was that yes indeed it had probably just been temperorily blocked!

Today, (winds 20-25, temp 73) i had the same thing occur. After thinking it over, I realized that on both occasions the wind was piping up (20-25) and the waves (seas for inland lake) were from the stearn quarter.

Is there any way that the waves/seas could be blocking the exhaust (most of the time it is under water while under cruising power)? After I allowed teh engine to cool, it ran fine all the way back to the slip!!!

BTW, the engine has been run regularily since september, and probably under the same conditions as today. I cant fingure this one out!!!!

Help

Bill
S/V Rhapsody
CD25D # 148

cd25d@clnk.com

[Ed Haley]

Certainly, if I add my guess to the dilemma it could cause no harm. Depending upon how high the waves were that you were encountering during your run (I assume you were heading into or with the wind since you had no heel), the stern of the boat could rise high enough on the crest of a wave so that your engine water intake thruhull comes out of the water. In this case it will suck air. If the wavelength is long enough, the air sucked into the intake line could cause the impeller to spin without water in the housing, preventing suction. If you have even a slightly worn impeller (or one with a broken vane) the air pocket could prevent the impeller from drawing water, especially if there is a sequence of air pockets waiting their turn to get to the impeller.

In reality, you are probably getting a reduced cooling water flow to your engine. Hence overheating.



eghaley@dreamscape.com

[Bill]

Nope

I was running (or maybe off the stearn quarter) with wave no more than 2 feet (inland lake with a short fetch, at this point). There is no way IMHO that the intake could have been exposed!!! Thanks for your input however, I'm still reaching for an answer.

BS

Certainly, if I add my guess to the dilemma it could cause no harm. Depending upon how high the waves were that you were encountering during your run (I assume you were heading into or with the wind since you had no heel), the stern of the boat could rise high enough on the crest of a wave so that your engine water intake thruhull comes out of the water. In this case it will suck air. If the wavelength is long enough, the air sucked into the intake line could cause the impeller to spin without water in the housing, preventing suction. If you have even a slightly worn impeller (or one with a broken vane) the air pocket could prevent the impeller from drawing water, especially if there is a sequence of air pockets waiting their turn to get to the impeller.

In reality, you are probably getting a reduced cooling water flow to your engine. Hence overheating.

cd25d@clnkl.com

[Loren Lyndaker]

My 1GM in a 1980 CD27 used to occasionally over-rev when I was motoring or motor-sailing in rough conditions. I eventually found the problem to be caused by oil from the crankcase getting into the breather hose that runs across the front of the engine to the air intake. I cured the problem by re-routing and extending the hose and installing a container to catch the oil that got in the line so that it wouldn't get into the engine. There was a fair amount of oil intercepted whenever I motored in rough conditions.

Well folks I have a question for you. In september I posted a note about the odds of a piece of debre blocking the intake for my 1GM cooling. The engine had overheated and everything looked to be in order below decks (impeller et al..) After letting it cool down, I ran it for 20-30 minutes without a problem. The consceince of this august body was that yes indeed it had probably just been temperorily blocked!

Today, (winds 20-25, temp 73) i had the same thing occur. After thinking it over, I realized that on both occasions the wind was piping up (20-25) and the waves (seas for inland lake) were from the stearn quarter.

Is there any way that the waves/seas could be blocking the exhaust (most of the time it is under water while under cruising power)? After I allowed teh engine to cool, it ran fine all the way back to the slip!!!

BTW, the engine has been run regularily since september, and probably under the same conditions as today. I cant fingure this one out!!!!

Help

Bill
S/V Rhapsody
CD25D # 148

[Tim Pinette]

I had a similar problem with the Yanmar in my CD27 several years ago. Sometimes it would run well for quite a while, while other times it would overheat after only a few minutes. After several fruitless attempts to figure out the problem, I was referred to Orr's Island Boatworks in Harpswell Me, which I've come to learn is the epicenter of Yanmar knowledge in the northeast. They replaced the very worn cam in my 16 year old water pump, and recommended that I remove the entire drain fitting under the cylinder head--to see if there was something too big to fit through the very narrow drain spigot. (Removal of the fitting gives about a 1/2" drain hole). When I removed it, about 1/3 cup of scale and assorted other junk came out. Since then, I remove that fitting at least once per season, sometimes flushing the engine by removing the zinc plug on the top of the engine. I don't know if it was the worn cam, the junk in the cooling system, or both, but I've not had a problem since.

Tim
Pegasus
CD27 #43



tpinette@ime.net