Urgent - Raw Water Pump Not Working!

[Vyndance]

Are the strainer and pump below the water line?

[colemj]

Originally Posted by Ex-Calif

One thing for sure is it has to be something!

"It's always something" - Roseanne Roseannadanna

[Don1500]

Originally Posted by bill352

Not exactly sure of the sequence of things, but if you installed the impeller with the vanes in the wrong direction, then ran the engine, then found the vanes still the wrong way, it is possible the shaft is not turning the impeller. They will usually straighten out on their own after a couple of turns.

OK. I thought the pump would correct any discrepancy in the vane direction but I wasn't sure. If you say it will I am happy.

For everyone else: I have checked the pump rotation (turned the motor over with the cover off), spins correctly, that's how I determined spin direction.

It is now 6:45 and I am getting set for another day wrapped around the engine. My hands are bruised and cut up from the hose clamps. My fingers are sore from turning the thumb screws holding the pump cover on. And I am just about ready to call a mechanic. But right now I probably know more about this system than he does. Yet somehow everything works but it doesn't pump.

[Wotname]

Hang in there, keep rational and don't assume anything and good luck tomorrow. On the plus side, you have a whole word full of engineering and fixers right by your virtual side.
Oh and look after those fingers

[cheoah]

Don, been there, it is frustrating. It will make the victory sweeter when you get back on the ICW. Still darkish up here in western NC in the mountains, hope it is a nice sunrise down there south of Cape Fear. Looks like small craft advisories for you there today anyway so maybe a good day for repair.

If you have water to the pump....and the path is clear to the outlet for sure, then it does seem like the pump is not pumping. As others have suggested, I would make sure the pump is all air tight. You might try the soap in a spray bottle trick to find an air leak in pump/hoses -while it is running. Since the engine is cold, you can run it longer getting it to prime or troubleshooting it. Good luck and safe travels. You'll be in Charleston before you know it, and will enjoy the Waccamaw.

Chase

[skipmac]

Had a similar, frustrating problem with getting air into my fuel system. Tried this and that for three days and could not get it to work. Finally solved the problem by eliminating ALL but one part of the system and putting parts back in one at a time. After reading all of your steps so far I would do this.

1. Get two, new short pieces of hose to fit your water pump (eliminates the possibility of the existing hoses collapsing internally).

2. Disconnect existing hoses on the water pump, in and out sides, and connect the two new hoses.

3. Stick the two new hoses into a bucket of water and crank engine. If water circulates in the bucket then the pump is working.

4. If water is not circulating time to rebuild something.

5. If water is circulating then connect the original output hose but leave the intake side in the bucket and crank again. If water is sucked out of the bucket and spray comes out of the exhaust then that sides of the system is good and not blocked.

6. If outlet side works then reconnect the intake side hose and see what happens.

This will at least isolate the problem to one of three areas: pump, intake, outlet.

Report back and move to the next step.

[Noname]

Same thing happened to me when I changed impeller on my 3gm30 a while ago; no water coming out of the exhaust. I closed the inlet thru-hull, disconnected the raw water hose from the strainer and forced water into the line with my garden hose, reconnected the raw water hose quickly to the strainer and then started the engine again. I pumped water almost immediately. Even though the raw water impeller pump should be self-priming--it wasn't in my case. By the way, I found the garden hose is the easiest way for me to re-prime my air conditioning water pump in case is loses its prime. Its worth a try.

[unbusted67]

Originally Posted by Seaduction

Same thing happened to me when I changed impeller on my 3gm30 a while ago; no water coming out of the exhaust. I closed the inlet thru-hull, disconnected the raw water hose from the strainer and forced water into the line with my garden hose, reconnected the raw water hose quickly to the strainer and then started the engine again. I pumped water almost immediately. Even though the raw water impeller pump should be self-priming--it wasn't in my case. By the way, I found the garden hose is the easiest way for me to re-prime my air conditioning water pump in case is loses its prime. Its worth a try.

Isn't that is a dangerous move though because you can get vapor lock in your exhaust system?

[Play Actor]

I had a recurring problem exactly like this for several years.

In my case, the the culprit was an airlock. You probably sucked air into the system on the violent roll. If the raw water line has a high spot in the wrong place, you can get air trapped in there, and you'll shut off the flow. I would just burp the sysytem and go on, once I learned where the airlock occurred, until I finally got tired and replumbed it.

This is common if the intake line from the seacock to the pump has a high spot -- higher than the pump, and especially if it's higher than the waterline. When you disconnect the intake hose from the raw water pump, assuming the pump end of the hose is below the water line, you should get a continuous, steady flow of water from the hose, not just a trickle, but enough to worry you. Hold it over a bucket. If you don't have that, then trace the hose back to the seacock. If any portion of the run is above the waterline, it's prone to airlock, even with an impeller pump. Open the joints until you find water.

Once you have a gusher from the end of the hose, put it back on the pump, and disconnect the discharge hose from the pump. Put another hose on the discharge and run it to your bucket. Start the engine. You shoud have a flow of 3 plus gpm, depending on the engine. If you don't have that, and you have plenty of water getting to them pump, you have a pump problem, but it sounds like you've overhauled the pump. If you have that, put it back together and try again. If you don't have water coming out of the exhaust at a 3 plus gpm rate (You can hang your bucket under the exhaust) then keep following that discharge hose, disconnecting each joint, to the heat exchanger input and output and beyond, running the engineat each step, and looking for the flow rate. If you get as far as the exhaust elbow and you have water flow, you should be fixed. If not, you probably have an exhaust elbow problem.

Airlock rarely happens on the discharge side of an impeller pump, but it's fairly common with centrifugal pumps mounted right at the waterline (maybe your heater problem.) The long term solution is to replumb to eliminate the high spot.

Based on the coincidence of your problem with the violent roll, airlock is my bet. I used to have the probelm every time I started the engine after a wild offshore passge.

Good luck.

[psneeld]

If you sucked in air just from a wake, I would be suprised. How close to the keel is your intake and do you really think it sucked enough air to air lock it?

Next...stop jumping around based on suggestions...you have enough to go through the system and specifically eliminate possibilities from intake seacock to exhaust. The only failure that I could see easily skipping over is a delaminated suppy hose that will collapse under suction but seems fine when you blow through it or let water flow though it...those can be aggravating but like someone suggested...another piece of hose in a bucket eliminated that.

And for those who say your pump may not self prime...if it doesn't it's time for a new one or a rebuild if possible...if it doesn't self prime it's worthless on an engine as I would consider that a safety issue (assuming you consider the immediate use of an engine as a safety issue).

[Don1500]

FIXED!!!! Clog on the output of the heat exchanger! I took of the hose from the pump to the HE and ran a new piece to a bucket, the pump pumped. Then I hooked up the new hose to the heat exchanger and blew through it, hard at first but then I had bubbles. hooked everything back up and she pumped like normal!! I feel like hooking up the output of my water maker to the pump to make sure I always have clean water going through! In any event I am going to look for a better strainer. The installed one is a small piece of plastic not a nice big glass and brass, like my heater strainer that also got clogged. I continue my trip to Florida tomorrow, this is now a day of rest (After I clean everything up.)

[atoll]

well done,you have learnt a valuable lesson,about the elimination prosess,when fault finding on a boat!

[Noname]

Originally Posted by Don1500

FIXED!!!! Clog on the output of the heat exchanger! I took of the hose from the pump to the HE and ran a new piece to a bucket, the pump pumped. Then I hooked up the new hose to the heat exchanger and blew through it, hard at first but then I had bubbles. hooked everything back up and she pumped like normal!! I feel like hooking up the output of my water maker to the pump to make sure I always have clean water going through! In any event I am going to look for a better strainer. The installed one is a small piece of plastic not a nice big glass and brass, like my heater strainer that also got clogged. I continue my trip to Florida tomorrow, this is now a day of rest (After I clean everything up.)

Don,
I like my new Groco strainer.
Easy to install, etc. I put 2 of them in this summer.

[Noname]

Originally Posted by unbusted67

Isn't that is a dangerous move though because you can get vapor lock in your exhaust system?

Not a problem because the garden hose stream only got to the impeller and couldn't flow beyond that point, but it did prime the pump. My line does have a high spot in it that can air-lock. Its new hose but it is extra long in case I have to cut a bit off the end where its clamped onto the raw water pump.

[cal40john]

I thought you did this back on post #31. Do you know what the difference was? Didn't run it long enough?

John

Originally Posted by Don1500

Ran for 30 seconds with the output hose disconnected, no water in bilge. It's not pumping. I am going to remove the input again and see if I can blow to the strainer.

Originally Posted by Don1500

FIXED!!!! Clog on the output of the heat exchanger! I took of the hose from the pump to the HE and ran a new piece to a bucket, the pump pumped. Then I hooked up the new hose to the heat exchanger and blew through it, hard at first but then I had bubbles. hooked everything back up and she pumped like normal!! I feel like hooking up the output of my water maker to the pump to make sure I always have clean water going through! In any event I am going to look for a better strainer. The installed one is a small piece of plastic not a nice big glass and brass, like my heater strainer that also got clogged. I continue my trip to Florida tomorrow, this is now a day of rest (After I clean everything up.)