quick lesson on volvo 305 cooling please

[pine island fred]

Just got a call from my friend broke down at marker 34 on icw. Engine shut down temp was 140 on shut down and climbed to 180 static. Said engine was hot. Removed thermostat cover, cranked on starter and got no water flow. Sea water pump replaced 1 yr. ago and has all of about 2 hrs operating time since then.<br /> Has a cabin/beer so they are good for the night as it is getting to dark for a tow. Question, what am i looking at tomarrow? Figure the sea water pump feeds the circulation pump. Would think the circulation pump has got to provide manifold cooling water all the time. Which way does the rest of the water go? Says the thermostat housing has 4 hoses atached to it. What goes where? Can someone give me a block flow discription ? It is a 290 DP with a salt water cooled small block CHEVY. Thank you very much. FRED. PS. bondo, never did put the vegatable oil in the tilt/trim! regards

 

[Don S]

Re: quick lesson on volvo 305 cooling please

What usually happens is a plastic bag gets sucked over the intake on the drive and destroys the pump impeller due to lack of water. Not sure what model Volvo 305 you have or what year, but here is a fairly common system for Volvo.<br /><br /><br />

 

[TilliamWe]

Re: quick lesson on volvo 305 cooling please

shut down at 140? Only rose to 180? That's not hot at all. But I'll have to believe you all that there was no water flow. It's the impeller in the drive. The "water pump" on the engine just circulates water in the block. It is almost unnecessary. As a matter of fact on high HP applications & fancy custom motors, they eliminate it. The boat will most likely have to be hauled out to determine exactly what is wrong. I'd double check that "no water flow" theory again.

 

[pine island fred]

Re: quick lesson on volvo 305 cooling please

Thanks don! Looks to me like the sea water pump is the one responsable for the constant cooling for the manifolds. Circulation pump cools the engine. Should be interesting tearing into. Bet you are right on the plastic bag! Oh, SEA TOW came and got him after dark. fred

 

[Don S]

Re: quick lesson on volvo 305 cooling please

Fred, the sea water pump FEEDS the engine Circulation pump. No water to the circ pump and it ain't gonna pump.<br />TW. Lots of engines overheat without the gauge showing when there is no water around the sender. They don't read air temp worth a dang.

 

[TilliamWe]

Re: quick lesson on volvo 305 cooling please

that is true don, they are not air temp guages. But doesn't it make sense that the last water that was in there was hotter than 140? And the fact that it rose to 180 tells me there was water in there. <br />When an impeller fails, does it actually "pump" air?

 

[pine island fred]

Re: quick lesson on volvo 305 cooling please

Yes, 140 did not sound like an overheat to me and cranking the motor on the starter might not have turned the pump enough to push water around. I was not there just on the phone so it is hard to tell. No pump in the leg on this one, just the engine driven pump. fred

 

[Don S]

Re: quick lesson on volvo 305 cooling please

It won't pump air so to speak, but the circ pump and the seawater pump working together drops the level of the water below the sender. That's when the overheat starts, because the water no longer ciruclates, it just sits in the block and boils. But the sender is only seeing hot air.

 

[Bondo]

Re: quick lesson on volvo 305 cooling please

Ayuh,.......<br /><br />It's My thoughts that the "Heat Sink" effect is a Steam condition,........<br />By the time the sender is out of the liquid water,... There Are hot spots in the Heads,.....<br />When the motor is shut-down Heat will migrate to the Uncooled portions of the heads,+ Cause Steam to fill the Vacant cavities........<br /><br />I Think that's Why a heat gauge will Rise when shut-down in an Over Heat situation...............