VOLVO PENTA AQ 280 NO WATER GETTING TO PUMP NARROWED DOWN

fish4boats

Seaman
Joined
Apr 26, 2016
Messages
71
Ok I think I have this narrowed down. It's a 1978 chris craft cruiser that's overheating. I unhooked the mainline to the sheerwood pump leaving only the water inlet hose to the bottom of the sheerwood. I started the boat leaving run for a very short time but no water pumped out of the pump.

What I've done and checked

1. New impeller put in. But one brand new one up already.
2. The inlet hose is fine no tears or cracks.
3. All hose clamps are tight
4. Replaced the thermostat "old one came apart

Initial problem

But started to overheat slightly then overheated unless not underway and at high rpm.

Picture inside of motor compartment shows a missing hose to rwp inlet. I just removed this hose. It was connected prior to


Questions

Does entire cooling system need connected for the suction of the water or should it pump with only lines from outdrive to raw water pump inlet. Should it pump out of the out of the rwp.
​The bottom nine pictures are the newest pictures

Any help would be immensely appreciated
 
Last edited:

72fj40

Petty Officer 2nd Class
Joined
Jul 16, 2013
Messages
142
Check the hose on the outdrive that connects to the transom plate, that is a service item along with the water neck and gasket mounted on the o/d that it attaches to. The water neck is designed to detriorate. You won't get water if it sucks air in that area. I would think the pump should pump if the out is not hooked up. Something like 9 gal a minute.

If you're running it muffs, there's a hole in the bottom of the o/d that needs to be blocked off.
 
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Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,430
Yep, check the inlet casting. Most likely it is corroded to nothing
 

fish4boats

Seaman
Joined
Apr 26, 2016
Messages
71
Do I need to pull the outdrive off. The hose from the o/d to the transom plate is fine
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,849
Your description is confusing. When does it overheat while in the water? at idle? When the boat is on plane?

But started to overheat slightly then overheated unless not underway and at high rpm.

Does this cool it down every time? running at high RPM?
 

fish4boats

Seaman
Joined
Apr 26, 2016
Messages
71
It heats up on plane and when idling. Usually cools down when running at higher rpm
 
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