2003 Volvo Penta 3.0 with SX overheating - perplexed

cattouchard

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Joined
Jun 17, 2020
Messages
1
Just about a boat with the Volvo Penta engine. Went out on water and boat overheated. So far I have changed the thermostat and impeller. When I drop the lower unit in a very large bucket of water and run it I get no water out of the exhaust and it runs hot. BUT when I force feed it with fresh water via hose it runs cool. What does this tell you? Anything? The only other thing I can thing about is the pump itself.
 

Pavpav

Cadet
Joined
Jun 19, 2020
Messages
19
Check your hose between stern and hull, also the hose between the hull and water pump, also the hose for flushing and make sure the cap is on tight. The other thing to check is the internal circ pump. There's no much else to it.
 

GA_Boater

Honorary Moderator Emeritus
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May 24, 2011
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49,038
When I drop the lower unit in a very large bucket of water and run it I get no water out of the exhaust and it runs hot. BUT when I force feed it with fresh water via hose it runs cool. What does this tell you? Anything? The only other thing I can thing about is the pump itself.

Welcome aboard.

What it tells you is the bucket isn't big enough and deep enough. Water level must be well above the inlets on the side of the lower unit. The water pump impeller is above the inlets and the pump must be submerged. Water should be over the av plate.



vpsxlu.png
 

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
71,283
Just about a boat with the Volvo Penta engine. Went out on water and boat overheated. So far I have changed the thermostat and impeller. When I drop the lower unit in a very large bucket of water and run it I get no water out of the exhaust and it runs hot. BUT when I force feed it with fresh water via hose it runs cool. What does this tell you? Anything? The only other thing I can thing about is the pump itself.


Ayuh,...... Welcome Aboard,...... I/Os won't suck water from a bucket, get a set of muffs to run it on a hose,......
 

Geeski

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Joined
Jun 21, 2020
Messages
2
when my impeller failed it left tiny little rubber fins everywhere restricting water flow. and definitely get some water muffs
 

Lou C

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Nov 10, 2002
Messages
13,317
The impeller on a Volvo Penta is about 8-12” above the height of the water intakes but as far as 4’ forward because it’s mounted low on the front of the engine. There is NO WAY it will prime in a bucket or trough! In fact you need the best fitting muffs that you can get because impellers do not suck air only water....
in fact a sure fire way to get it to prime is to hook up the muffs. Then go up to the front of the engine and disconnect the water feed hose from the transom to the impeller. Hold it up and fill that hose with water. Then reconnect the hose and turn on the water.
When the boats in the water, due to the fact that this hose is below the water line static water pressure forces water in this hose. On land you need the water pressure of the hose to do this but if your muffs don’t seal well you will have trouble getting it to prime..remember impellers can move only water not air!
 
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