Volvo Penta 5.7 cooling system malfunctioning

Onebeeg1

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Oct 14, 2009
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My '98 Volvo Penta 5.7 is overheating. I just bought the boat and changed the thermostat, and there wasn't any water in the thermostat housing. However, there was water in the block and exhaust when I removed the drain plugs. The boat is out of the water, so I can't perform pump tests. Everything is so hard to get to does anyone have any good ideas about what to check next?
 

Don S

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Aug 31, 2004
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Re: Volvo Penta 5.7 cooling system malfunctioning

Did you ever replace the raw water pump impeller? That is the first thing you check on an IO overheat. That impeller should be replaced every other year.
 

Bondo

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Apr 17, 2002
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Re: Volvo Penta 5.7 cooling system malfunctioning

Everything is so hard to get to

Ayuh,... Welcome to the Wonderful World of Wrenchin' on Boats....
 

Pondman2008

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Aug 31, 2010
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Re: Volvo Penta 5.7 cooling system malfunctioning

Did you ever replace the raw water pump impeller? That is the first thing you check on an IO overheat. That impeller should be replaced every other year.

I haven't figured out how to ask a new question as yet. Perhaps you could comment. I have 1969 Chris Craft with two Buick V6 & 280 Volvo Penta sterns. One unit works great. The other I suspect has had cooling problem for long time. When pulling water from stern, I pull half air and engine over heats. If I hook it up to the other stern, it pulls 100% water & runs cool. I added hose extension over the side & it works fine. Any idea where I draw air from the stern? I reverse the hose on the stern with overheating results. Would I danmage the stern if I finish off this summer with hose through the transum?
 
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