1GM Overheating, the Saga continues

[Bill]

Hi to all, we here in Oklahoma had a glorious sail today!

Okay, in July I did the following:

Replaced the thermastat,

removed and checked the mixing elbow

check the impeller

the engine did not overheat for sever operating hours, and then Friday, is happened again. I have however noticed that the TONE of the exhaust changes from time to time and that there is no water being pumped when this occurs! That should at least tell me that there is a cooling water problem. However, since it goes for long periods of time between occurances, that should rule out the impeller SHOULDNT IT????

Which would leave the water pump, or the muffler!

Can the muffler cause a problem on this manner?

How would the water pump be sooo intermintent (sp) as to cause the problem?

Thanks in advance for you comments/suggestions.

Bill



cd25d@rhapsodysails.com

[Jerry]

Hi to all, we here in Oklahoma had a glorious sail today!

Okay, in July I did the following:

Replaced the thermastat,

removed and checked the mixing elbow

check the impeller

the engine did not overheat for sever operating hours, and then Friday, is happened again. I have however noticed that the TONE of the exhaust changes from time to time and that there is no water being pumped when this occurs! That should at least tell me that there is a cooling water problem. However, since it goes for long periods of time between occurances, that should rule out the impeller SHOULDNT IT????

Which would leave the water pump, or the muffler!

Can the muffler cause a problem on this manner?

How would the water pump be sooo intermintent (sp) as to cause the problem?

Thanks in advance for you comments/suggestions.

Bill

Take a close look at the impeller. I have had two that looked great but center had come loose from the impeller. It may be turning intermitently.



jlecocq@milehigh.net

[Mike Greenberg]

How long have you owned your boat? Do you have a heat exchanger?



mikegre@idt.net

[Bill]

How long have you owned your boat?

Two years

Do you have a heat exchanger?

(Stupid me) I dont think so, unless the high lift muffler severs as an exchanger!

All hoses have been checked for blockage!

Am going to replace impeller, and if that doesnt work, I'm going to do the pump.

BS



cd25d@rhapsodysails.com

[Lee H. Hodsdon]

Bill,

the engine did not overheat for sever operating hours, and then Friday, is happened again. I have however noticed that the TONE of the exhaust changes from time to time and that there is no water being pumped when this occurs! That should at least tell me that there is a cooling water problem. However, since it goes for long periods of time between occurances, that should rule out the impeller SHOULDNT IT????

I certainly sounds like the water pump to me. Decreased flow through the system causes just the symptoms above, overheating and increased exhaust note.

How many hours on the water pump? Wear can occur in the impeller, the cam at the top of the pump and the fit of the cover plate. Any of these three will decrease the water flow through your engine. The cam is easy to replace, one screw at the top. Though expensive, a new pump may be the ticket.

Could also be the pump is loosing its' prime. Is the intake clear of all debris, growth and other stuff (technical term)?

I can not see the muffler causing any problems. I have a 1GM Manual at home from a seminar at Hansen. I'll look at it and see what they recommend, though I suspect you have already done the same.

Best of Luck,

Lee



lhodsdon@nh.ultranet.com

[Matt Cawthorne]

Bill,
The change in tone of the exhaust is due to there being no water in the muffler. When no cooling water enters, the muffler is not as effective. I think the defective impeller is a good place to start, but there is yet another theory.
My brother had overheating problems on a raw water cooled volvo. It was caused by a tiny air leak in the strainer that allowed air to get in. He would then loose the prime and the engine would overheat. The air leaked through an old gasket in the top of the unit. His strainer was above the waterline. The gasket was only a few dollars and the problem was solved.

Good luck,
Matt

Hi to all, we here in Oklahoma had a glorious sail today!

Okay, in July I did the following:

Replaced the thermastat,

removed and checked the mixing elbow

check the impeller

the engine did not overheat for sever operating hours, and then Friday, is happened again. I have however noticed that the TONE of the exhaust changes from time to time and that there is no water being pumped when this occurs! That should at least tell me that there is a cooling water problem. However, since it goes for long periods of time between occurances, that should rule out the impeller SHOULDNT IT????

Which would leave the water pump, or the muffler!

Can the muffler cause a problem on this manner?

How would the water pump be sooo intermintent (sp) as to cause the problem?

Thanks in advance for you comments/suggestions.

Bill

mcawthor@bellatlantic.net

[M. R. Bober]

It's worth a look.
Shaft



thebobers@erols.com

[Bill]

My brother had overheating problems on a raw water cooled volvo. It was caused by a tiny air leak in the strainer that allowed air to get in. He would then loose the prime and the engine would overheat. The air leaked through an old gasket in the top of the unit. His strainer was above the waterline. The gasket was only a few dollars and the problem was solved.

Good luck,
Matt

Matt,

Once you lose prime, can it be recovered just by sitting and the engine cool off. After the engine cools, I start her up, and she may run fine for a month or more (or longer). Does the lose of prime self-correct in a relatively short time (albiet not permentantly self-corrected)?


BTW, my water intake comes straight form the thru-hull into the pump, no stainer. It there is an air leak it is in the hose or pump itself.

thanks
Bill



cd25d@rhapsodysails.com

[Bill]

It's worth a look.
Shaft

Yes, I have removed the elbow. Very clean. By shaft do you mean the pump shaft??? If so, no I have not checked that yet and trying to exhaust all cheaper possibilities first.

thanks

BS



cd25d@rhapsodysails.com

[Mike Greenberg]

Do you have a heat exchanger?

(Stupid me) I dont think so, unless the high lift muffler severs as an exchanger!

Bill:

If you can make hot water by running your engine, then you do have a heat exchanger.

So, do you? I have a reason for asking.



mikegre@idt.net

[bill]

Do you have a heat exchanger?

(Stupid me) I dont think so, unless the high lift muffler severs as an exchanger!

Bill:

If you can make hot water by running your engine, then you do have a heat exchanger.

So, do you? I have a reason for asking.

I have no exchanger!

BS



cd25d@rhapsodysails.com