Question about Water level for water impeller to function.

[tumblebug1949]

First off, let me identify my engine. It is a 1999, 40hp, two cylinder Force motor. It does not have a tale tell water stream that shows you the impeller is pumping and water is circulating but instead has a small spout on the top cylinder which a hose connects to going to a pressure gauge on the instrument panel. I may in the future split this line to provide a tale tell stream.

I bought this pontoon during the winter and put it in a large tub of water today before I trailered it to the lake for the first time. I wanted to get it in the water and run the motor some to just get used to how it handled. Before I went, I decided to put it in a trashcan full of water and start the motor before I hauled it all the way to the lake. I put it in water and the water level was well over the water intake holes. I removed the cowling and cut the small hose leading to the pressure gauge. That way I would have water squirting out if the pump was working. I started the motor and let it idle but there was no water coming from the small outlet. I let it run for a couple of minutes until the cylinder head was warm to the touch but you could still lay your hand on it. Still no water. Then I shut it off.

Here is my question. Is it possible that I did not have the motor low enough in the water. The water level was right at the cavitation plate. On this motor, there are exhaust slots just above the cavitation plate right above the small trim tab.
These were not in the water. I think I did not have the motor down in the water enough. I think the water level needs to be a few inches above the cavitation plate for the water to reach the pump housing. (((Let me know if this thought is correct.)))

I am sure the impeller needed to be replaced anyway but if I ran it with out water getting to the pump housing, I would need to be rebuilt even if it had been new.

The seller told me he bought the pontoon from his brother who bought it new in 1999. He said he did not think the impeller had ever been changed so I had already bought a pump rebuild kit so I was going to change it anyway. I just wanted to put it into the lake for a quick test to make sure everything worked. Well, I did not get to the lake but will now be replacing the impeller first.

Any constructive comments would be appreciated.

Tom

 

[wickware]

Re: Question about Water level for water impeller to function.

My 1970 35 HP Chrysler has to be deep in a deep barrel Basically Emulating the lake?s level on the motor for it to pump instantly and well. It blew my mind when it would not pump instantly 2? higher due to being on jack stands.

Plus, I feel muffs are forcing cooling water through the engine vs the impeller pumping the water, Correct? Finally, I like the solid stream of cooling water from the Tell Tale due to no exhaust mixed with the stream (attached).

 

[Nordin]

Re: Question about Water level for water impeller to function.

The waterlevel need to be minimum just above the waterimpellerhousing and it is just at the split lowerunit/motorleg.
Waterimpellerpumps on OB are not self-priming they need to have water in the housing when it starts to pump.
Anyway replace the impeller because it is normal maintenance and you do not know it?s condition.

 

[jerryjerry05]

Re: Question about Water level for water impeller to function.

The pump needs to be underwater to function. It's possible it might pick up at a lower level,but not likley.
If you split the hose from the pressure guage,it won't work as your cutting the supply.
It will indicate there is water pumping but thats all.
The muffs are for a system that you know works.
The hose will supply enough water for slow speed operation but thats all.
Never walk away from a motor running on a hose.
Never start without muffs.Make sure the muffs fit tight.

 

[Alwhite00]

Re: Question about Water level for water impeller to function.

If you do end up splitting it I don't believe the gauge would register any more as the pressure would be bled off, Correct?

LK

 

[tumblebug1949]

Re: Question about Water level for water impeller to function.

Thanks everyone for your response. I am sure I did not have the water level high enough to be above the pump housing. I had not considered the pump not being self priming and thought (wrongly) that if the water inlet holes were covered that I was ok. I will never make that mistake again. At least I was going to replace the impeller anyway although I really do hate to make dumb mistakes. I will get that taken care of this afternoon. And because I was checking to see if the impeller was pumping water anyway, I was making sure the motor did not get too hot.

I do have a set of muffs that I have never used. I had thought it would push water through the motor thus not give me an accurate indication of what condition the impeller was in. For me, I know the condition of the impeller now. Fried. At least I did it with out hurting anything else.

As far as splitting the water between the gauge and a tell tail. I have been led to believe that if I use a small diameter tip for the water outlet that I will have the tell tail and still get a small reading on the gauge to show the pump is working.

Is this correct or am I better leaving the system the way it was designed. This is a pontoon with a railing all the way around so I will not be able to see it while setting at the steering wheel. I was just a little worried about trusting the gauge.

Thanks again to all that commented on my question.

Tom

 

[jerryjerry05]

Re: Question about Water level for water impeller to function.

Don't splice it.
Make sure the hose is clear.
Learn to trust it.
You sure the overheat alarm works?
Key on.
Ground out the temp sending unit.
That should make the buzzer sound off.

 

[tumblebug1949]

Re: Question about Water level for water impeller to function.

Thanks JJ,

I will check temp sending unit.

I put the new impeller in yesterday and was happily surprised. First I checked out a video on youtube and will say it was very detailed and hugh help. Then I changed the impeller and to my amazement, it went like clockwork. Every step was was simple and the parts fit perfectly. I am not used to that.

The old impeller was actually not in bad shape. All the paddles were there with just slight wear but I could see slight cracks in the rubber from age.

Now the impeller is new and I have no problem trusting it.

While trying to get the lower unit (drive shaft and shifter rod) back into the motor housing, it was difficult to get the shifter rod through the small hole it need to fit through. After several tries with no luck, I went to the garage and got a 4 inch length of a clean plastic drinking straw. I pushed the section of straw through the hole from the top so it was sticking down into the inner housing. Then when I slid the drive shaft and shift rod back into the housing I could see it and I stuck the end of the shift rod right into the open end of the straw. That little piece of plastic slid up as the lower unit moved up and it guided the shift rod right through the hole.

While I had the lower unit out, I noticed a slight amount of oil around the oil vent plug. After the lower unit was installed, I checked the threaded vent plug out. I found that the oil was new which I expected because the prior owner told me he had changed the oil. But the top plug did not have a gasket on it and was the plug with the magnet. So, the plugs had been switched and were in the wrong place plus the magnetic plug had no gasket on it. I think with getting warm and cooling during operation, it would have drawn in water. Really glad I checked it. I already had the new fiber gasket here to fix the problem.

Ok, hope everyone has a good year.

Tom