Water pump problems

[snaiken]

I've been trying to help a buddy with his water pump problem and I can't seem to figure this one out.
It's in a universal 2 cylinder, can't think of the model. For some reason we can not figure out why it won't pump water! We have installed three different pumps, two spare ones and put in two new impellers on each one and one brand new one, still no water. Now, we have checked to make sure the valve is open and that there is nothing blocking the through hull. We have removed the intake hose from the pump and siphoned the water into the bilge and there seems to be no restrictions there. We connect the intake and disconnect the outlet from the pump, start it up for a minute or two to see if we are pumping water out directly from the pump and...nothing, nada, zippo! We've hooked it all up and primed everything as well as we could, several times and still no water, not coming out the exhaust or any exit from the pump back. This just has me baffled. I've been online looking up potential problems and for the life of me can't figure out why the pump isn't pumping.
Does any one have any ideas or had this happen to them? Thanks for any help.

[Noah]

On my old Volvo diesel the intake hose looked good, but the inner liner had actually collapsed - when the pump would suck it go no water, but otherwise it looked ok - new from the outside anyway.

There must be a blockage in the block somewhere. I had good luck flushing my engine with acid, but if there are non-metallic bits in the cooling system - shells, rubber bits from the impeller, etc it might be hard to clear.

[snaiken]

Now the inner lining is something I didn't think of and I'll check that out. I don't think it's blockage in the engine as I've taken the outlet hose directly off the pump and still no water. I can also blow through the engine and it seems to flow through fine. The inner lining though...hmmmm. Any other ideas out there?

[Peter Malcolm Jardine]

If the pump is belt driven, it may be running backwards. Orientation sometimes depended on the rotation of the engine. Check to see if the intake hose is clear... otherwise it should be at least pumping with the outlet hose off.

[Dave Davis]

Two thoughts. First, air getting in on the suction side; tight clamps, patent inside liner, no leaks in the hose. Second, impeller's not turning; missing its key, gear drive is broken (if not a belt driven pump). Ok a third, pump plate over the impeller is leaking (ok, corollary for the first thought).

[PeterSibley]

As Dave said and of course the really obvious one .........you don't have the inlet and outlet mixed up by any chance ?

[andrewe]

Re: Possible Inlet/ outlet. Mix-up. If you are looking at the pump and it rotates clock-wise the water is pumped from right to left.
Assuming a Jabsco type rubber impellor pump.
A

[Woxbox]

I've had that problem and the source was an air leak in the raw water filter. It depends on the installation, but the filter cap can suck air when the engine is on, but not leak water when the engine is not running.

Replacing the cork seal on the filter was a temporary fix, but we eventually replaced the entire filter to fix it permanently. For whatever reason, the filter cap (an old-style bronze unit) wouldn't seat properly and the air leak kept coming back.

[sv Lorelei]

If the A2 was like the A4 (which I think it was only two cylinders shorter) the water pump is gear driven through a set of gears that drive from the gear cast directly onto the rear of the crankshaft. It is possible (but not likely) that a key is sheared and a shaft worn badly enough so that the internal inertia of the pump keeps it from turning, or that a gear has thrown some teeth. Take off the pump and try turning the engine side pump drive coupling with something that fits in it. If it turns without the crankshaft moving that may be where your problem lies.

[snaiken]

You guys are great. Thanks for the responses. The pump is gear driven and I know it's turning because I've cranked it over with the cover off. No leaks around the pump that I can see, and we are on the third pump... I'm guessing that there must be air coming into the system. When my buddy first got the boat there was just a dribble coming out of the exhaust, for sure not enough. Since then we have been tinkering with it and now nothing at all comes out. We have it hooked up correctly as far as the inlet and outlet hoses. I'm going to investigate the raw water filter for air leaks. Any other suggestions? I'll report back what I find in the air leak and inner lining departments. Thanks again.

[Dave Davis]

One other thing it might be. Our old Bukh DV10 had a weep hole in the bottom of the pump assembly that served as an indicator when the o-ring sealing the gear driven pump shaft from the engine's internals was failing. Little dribble down the case was time to change out the o-ring. Might be something like that getting air in there.

[Bob Cleek]

I may not know what I'm talking about, but you mentioned "siphoning water into the bilge." Does your intake line have an above the waterline loop in it? Does it have a siphon breaking fitting at the top of the loop like in a bilge pump installation? Does your pump create enough suction to start the siphon? Is your pump sucking air through the siphon break fitting? Engine raw water intakes don't generally have anti-siphon loops in them.

BTW, your engine sounds like a Universal "Atomic 2." This is the same as the old Kermath "Sea Twin." Great little engines, but they can be tricky in their simplicity. I had one years ago that kept sucking water into the crankcase. Couldn't figure it out for the life of me. Rebuilt the engine three times! Ultimately, I discovered that the wet standpipe exhaust muffler/riser pipe INSIDE the standpipe had rusted out at the bottom. I'd rebuild the engine and it would start right up. When I turned it off, the water in the standpipe would drain back into the exhaust system and end up inside the engine! Who'd a thunk it?

[snaiken]

There is no siphon loop in the line. It will only siphon when I take the hose and put the end below the water line. The pump itself isn't below the water line. I'm out of town this week but have called my buddy with my new found info and I don't think he's made it to the boat to check it out yet.
One thought I had was to take the inlet line off the water filter and sick in in a clean bucket of water and take the outlet line off the pump and see if we can get the pump to pump out of the bucket.

[Hwyl]

There is no siphon loop in the line. It will only siphon when I take the hose and put the end below the water line. The pump itself isn't below the water line. I'm out of town this week but have called my buddy with my new found info and I don't think he's made it to the boat to check it out yet.
One thought I had was to take the inlet line off the water filter and sick in in a clean bucket of water and take the outlet line off the pump and see if we can get the pump to pump out of the bucket.

Or better still, put a hose pipe on the inlet, if water pumps through you've eliminated a lot of suspects, then try the bucket trick. I'm guessing it's a leak in your raw water strainer, try some vaseline on the impeller too, it will give the dry impeller better suction.