Troubleshooting raw water intake?

[Stamey]

I have this old Fibra boat with what I believe is an AQ200 Volvo out drive. It has a Sherwood pump mounted where you would normally see a PS pump on the 302 that's in this boat. It will not pick up water, on the muffs or in the water, out drive completely submerged. There is a transparent plastic hose running from the out drive fitting on the transom to the intake of the Sherwood pump and when running I can see the water and air in there moving a little, like it is sucking air into the pump, but does not seem to be moving the water.

In my troubleshooting steps I have done the following. Disconnected the intake hose form the Sherwood pump and connected it to the intake of a Northern Tool, fuel transfer pump, which is a positive displacement pump. Same thing occurs as with the Sherwood. I figured it was sucking air from someplace. Careful inspection of the hoses, including the hose beside the drive bellows showed no cracks or breaks in the hose. I then connected my garden hose to the water intake hose and back flushed though the out drive. I saw no leaks, so I clamped off the hose beside the bellows just before it entered the out drive, so I could pressure test the rest of the line. I did find a leak where the hose connects to the fitting at the transom, for the inside hose between the transom and Sherwood pump. I tighten a clamp to fix that.

Now, with the garden hose pressure on the line I have no leaks and reconnect it to the Northern Tool fuel transfer pump. Still does the same thing. Tried holding the muffs as tightly on the out drive as possible, to force as much water through the out drive as I can, but still not getting water up the intake hose inside the boat.

As I understand it, there is no impeller on this AQ200 out drive, so I am running out of ideas at this point and am wondering if you guys have any.

Thanks,
Chris

 

[Don S]

Re: Troubleshooting raw water intake?

Have you checked & replaced the impeller in the pump?

You mentioned it didn't work with the drive under water, did that mean the whole drive, includeing the top of the drive? Just trying to visualize how deep in the water it was and what would be under water.
The loose clamp inside will cause it to not suck water, once you burned up the impeller, it won't work after you fixed the air leak.

 

[Stamey]

Re: Troubleshooting raw water intake?

As far as I can tell, with what little info that is available on this out drive, there is no impeller in the out drive, hence the use of this Sherwood positive displacement pump. I even asked about it here before and was told they have no impeller in them. When I dunked it yesterday, the top of the out drive was about 3" under water. It almost seems like there is a blockage in the line someplace, but when back flushing it flows quite freely.

Thanks,
Chris

 

[Stamey]

Re: Troubleshooting raw water intake?

OK, dunked it again and once I revved it up quite a bit it did seem to pick up the water. Unfortunately it has now developed a carburetor issue and I'll have to fix that before I can continue with the cooling system.

Thanks,
Chris

 

[Don S]

Re: Troubleshooting raw water intake?

there is no impeller in the out drive, hence the use of this Sherwood positive displacement pump

I am aware of that. Volvo has never used a pump in the outdrive. What I am asking is have you checked the impeller since you have been having problems? it doesn't take much running with no water to damage the impeller, and from the sounds of it, you need a new one. You also need to give it a little throttle to get the water going. Usually around 1000 to 1200 rpm when starting gets water going to the pump.

 

[cr2k]

Re: Troubleshooting raw water intake?

Bypass the outdrive. Put a scupper and a seacock thru the bottom and run to your pump intake. Fixes the problem every time.

But if your impeller is toast nothing will help until it's replaced.