Can someone answer this question for me

[slickster2]

Gonna try to explain this and hope it makes sence a boat motors impeller has to be pumping water all the time to keep the motor cool whether In reverse or when going forward so why is there only one way the impeller fins go and would they not bend on there own depending which way the boat motor shaft turns do to the woodruff key holding the impeller from moving freely CAN any one answer this thanks

 

[Haffiman]

Re: Can someone answer this question for me

The driveshaft with the impeller turns the same way no matter in forward or reverse. Only the prop shaft changes direction.

 

[F_R]

Re: Can someone answer this question for me

Which is why the water pump was put on the drive shaft when they started making gearshift motors. Many motors built before that had the pump on the propeller shaft.

The gears that select the direction are in the lower unit, below the drive shaft and pump.

 

[aerobat]

Re: Can someone answer this question for me

Which is why the water pump was put on the drive shaft when they started making gearshift motors. Many motors built before that had the pump on the propeller shaft.

sure, because otherwise the pump would stop when idling at the dock in neutral- building it on the propshaft could only work in direct driven engines without neutral or reverse.

 

[Haffiman]

Re: Can someone answer this question for me

Back in the late 70's just before Volvo Penta closed shop with their outboards, they had a new series from 6 to 30 Hp ready to launch. On that line the impeller was down in front, and driven by the forward gear which always rotate same direction, neutral-forward or reverse.
As I worked in the R&D department at that time, I'm quite familiar with it.
The advantage was a more efficient pump making it possible to reduce impeller size, but the main disadvantage was sealing problems and water intrusion.
Personally I would say it was fortunate it never went into production!

 

[ohioriverat]

Re: Can someone answer this question for me

I guess, why do they always try to improve something that works so well with some crazy idea that just makes service work harder, like pulling the powerhead to unhook shift linkage

 

[Sprky]

Re: Can someone answer this question for me

On which motor do you have to remove the powerhead to get at the shift linkage?

 

[kfa4303]

Re: Can someone answer this question for me

some of the old 50's model 5.5-7.5 hp OMC motors require you to remove the power head to get to the shiftlinkage and other bits, but most larger/newer OMC motors have an access panel on the side. Thakf ully removing the power head really isn't that hard. There are only about 6-7 screws that you have to remove, but that's it. There's a vid on you tube that can show you the whole process.

 

[F_R]

Re: Can someone answer this question for me

Having to remove that powerhead was a blessing. It forced you to deal with the lower crankshaft seal which would fall apart if only the lower unit was removed. If that seal fails, it will slowly, but surely, destroy the powerhead bearings.

Of course, later models were redesigned to hold the seal captive. OK, I reckon, but I don't trust them. I still remove the powerhead for a looksee if it hasn't been sericed in a long while.

Back to the pump on the driveshaft---remember the Mercury Dockbusters? Pump on the drive shaft, which rotated both directions.

Champion motors was way ahead of Volvo with the pump driven by the forward gear. New ideas aren't always as new as they seem.

 

[wilde1j]

Re: Can someone answer this question for me

Champion motors was way ahead of Volvo with the pump driven by the forward gear. New ideas aren't always as new as they seem.

Truth is there are very few new ideas, period. You just have to look far enough, sometimes.

 

[Haffiman]

Re: Can someone answer this question for me

The head of the group was a rather interesting guy. The Swedes at Archimedes Penta inherited him from the bombed out factories of the German Heinkel aircraft after WW II.
His masterpiece was an inboard/outboard, even available with a two speed gearbox!

 

[slickster2]

Re: Can someone answer this question for me

ok can you point me in the right direction as to the way the fins on the water pump should be facing do to me doing them clock wise and no water pumping as well as counter clock wise with still no water pumping but all looks good in the pump no nicks or cracks in seals but water in bottom gear case thanks

 

[F_R]

Re: Can someone answer this question for me

The shaft turns clockwise. The impeller blades trail back. Think about it---it would be difficult to expect them to point forward and stay that way.

 

[lindy46]

Re: Can someone answer this question for me

Is the pin installed on the driveshaft which turns the impeller? Is the water tube in the grommet on top of the water pump housing?