www.iFourWinns.com

Yes. You have air entering the system and that will reduce water flow

Most likely not, you really can't run a Volvo in a tub like that because unless the impeller is in perfect condition, the impeller is not going to prime. Think about it, the drive is way back on the stern, the impeller is up on the engine, the water intake line is like close to 4 feet long, and full of air.The best way to run an I/O on land is with water muffs, the water pressure of the hose will help pressurize the water and allow the impeller to suck the water up that distance. Even an Alpha or a Cobra drive which has the impeller in the drive, may not prime in a tub, unless the water is up to the top of the drive. It needs the pressure of the water against the water intakes, for the impeller to be able to pull that water up that distance.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

To add to this, you ran the impella dry then. You may have damaged it.

Very possibly true, I'd take it out and inspect, replace if there is any doubt. Volvo says to replace every 2 years anyway.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

That makes sense, I will use the muffs from now on. However, isn't the fact tha water was getting to the circulation pump mean that the empeller was pulling the water up and not running dry?

I must be missing something.

How is having the drive in a tub o' water with the intakes properly covered, any different than the boat sitting at the dock in the water?

Greg

ps

the air pump on the Mercruiser drain system only actuates the drain valves, it does not pump any air into the cooling system.

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2008 210SS 6.2L DTS Bravo 1 Now featuring MercMonitor w/SmartTow

After researching it a bit, it seems that when the boat is in the water the water pump is below the water line, thus allowing the water to be forced to the pump?

Maybe...

Any other ideas?

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2008 210SS 6.2L DTS Bravo 1 Now featuring MercMonitor w/SmartTow

When the boat is in the water, the outdrive and transom assembly is essentially completely under water; that can't happen when the outdrive is in a tub of water; it's only the lower unit that is. So, there is a greater static pressure at the inlet due to the head of water above the inlet. Also, the whole water inlet hose is below the water line, so that hose will tend to be always full of water (the impellor/ housing is not airtight, so any air in the line on/ after launching will be forced out by the static water pressure) . For an outboard or a Mercruiser Alpha in a tub of water, with their pumps in the lower unit, the pump does get sufficient head of water to allow it to pump water.

Well, when you put it like that...

Thanks for the very complete explanation.

I will continue to use the muffs. The one time I used the tub method I kept a close watch with an external digital thermometer and the exhaust manifolds did stay cold. But better safe than sorry.

Greg

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2008 210SS 6.2L DTS Bravo 1 Now featuring MercMonitor w/SmartTow

I learned about priming etc when trying to use one of those big tanks you can use to suck up AF to winterize. Which is a bad idea for 2 reasons, one, you will not always get AF throughout the engine because the thermo may not open all the way, and even with the tank sitting on the swim platform above the drive, it still may not prime because there is not enough pressure. Impellers are designed to suck water not air, so you want that raw water intake line full of water. I actually thought of using a bilge pump to pressurize the flow from the tank, but I'd only use that on an engine with closed cooling for winterizing.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Just wanted to thank everyone for your help and advice. I was able to replace the circulation pump without the assistance of an overpriced boat shop. I am happy to report that everything turned out as planned and with my newfound confidence I replaced spark plugs, water fuel separator and cleaned the carburetor. I can't thank you all enough and truly believe this forum is a invaluable asset to any boater as a result of your knowledge and kind nature.

Thanks Ben

I will be replacing my circulation pump this spring. Glad to hear it is not too difficult.

Glad to hear it, you CAN do it, that is one of nice things about the old tech engines (ha ha, that's for you ric) they are SIMPLE and CHEAP for a do it yourselfer to work on. Changing the circulation pump is an easy job and the parts cost is minimal.

Any future questions that anyone has, post away, because whatever it is, one of us has done it.
Another great forum are the I/O forums at
http://www.iboatscom. There are some real pros there.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

When you change it, check the pulley alignment; the front flange on which the pulley mounts is pressed onto the shaft. There can be some variation in how far it has been pressed on.