Urgent - Raw Water Pump Not Working!

[Don1500]

Today (1/14/12) has gone from bad to worse! Started out aground at the dock. I waited for the tide and got away 4 hours later than I wanted.

18 miles into the trip I get swamped by a large cruiser going balls to the wall down the ICW. He was reported not only by me but three marina owners, the TowBoatsUS owner, and one home owner.

But after the rocking and rolling stopped my water pump">raw water pump wasn't pumping. I shut down as soon as the temp hit 185. (about 2 minutes) I called the Coast Guard telling them I was adrift in the ICW near G25 just before mile 365. BoatsUS heard the call and the owner knew the area was replete with rocks so he jumped into his boat and came to my rescue. I knew I was going to ground so I found a soft stretch of sand and hit it going about .1 knt. I got an anchor out to keep me from turning. BoatUS showed up and towed me to Osprey Marina, where I sit.

I checked the strainer, good, hoses, not clogged, impeller, good. But she still won't pump. I think she lost the siphon from the pump to the exhust but I don't know how to check. It was a very violent rock and roll that boat gave me. Anyone out there have an answer or something else to check? I am stuck here until I fix this.

[delmarrey]

If all parts are OK check the inlet. Plastic bags are great for getting sucked up. Also see that the strainer is not allowing air to get in, causing a air pocket.

[Don1500]

Originally Posted by delmarrey

If all parts are OK check the inlet. Plastic bags are great for getting sucked up. Also see that the strainer is not allowing air to get in, causing a air pocket.

Checked and double checked. Cleaned the clean strainer twice, opened the seacock (a very little) and water came through. I disconnected the inlet to the pump and was able to blow back to the strainer. That's why I'm thinking about a siphon loss, shouldn't there be water there? I know it's suposed to be selfpriming but it may need some back pressure to do this.

[atoll]

have you checked the impellor is not shredded

[Don1500]

Originally Posted by atoll

have you checked the impellor is not shredded

Yes, I took it out and inspected it, put it back with a new coat of impeller lube.

[atoll]

take the out let side f hose off the impellor pump and start the engine see if water flow,s if not prob is between pump and sea cock,if it does flow prob is up stream

[delmarrey]

Originally Posted by Don1500

I checked the strainer, good, hoses, not clogged, impeller, good. But she still won't pump. I think she lost the siphon from the pump to the exhust but I don't know how to check. It was a very violent rock and roll that boat gave me. Anyone out there have an answer or something else to check? I am stuck here until I fix this.

Rubber impeller pumps don't need a prime. The only other thing could be is it's plugged up, up steam from the pump. Have you inspected the core of the heat exchanger?

Is the pump turning? Try disconnecting the outlet hose of the pump and crank the motor.

[Don1500]

That's going to be my next move. I may get water all over but I'll know.

What about that thingy on top of the siphon break? The top of the "U". Would I be able to check there? Or should I just start at the pump?

[atoll]

that thingy is an anti siphon,normally a ball,that closes a hole on top when water is pushed thru the loop,then drops when engine stops allowing air in and breaks any siphon effect as the water finds its lowest point

[Ex-Calif]

Originally Posted by Don1500

That's going to be my next move. I may get water all over but I'll know.

Make sure the impeller key is there, the impeller may also have a brass center that is separated from the rubber allowing the hub to spin and not the impeller.

[zippy]

I had an ongoing problem with my raw water pump a few years ago when it would randomly stop pumping water. I replaced the gasket and impellor, checked everything numerous times, but it kept happening. It was very frustrating. On one of my many trouble shooting disassemblies I noticed some wear on on the plate covering the impellor so I sanded the plate until it was completely smooth. That solved my problem and it never reoccured.

[delmarrey]

Originally Posted by Don1500

That's going to be my next move. I may get water all over but I'll know.

What about that thingy on top of the siphon break? The top of the "U". Would I be able to check there? Or should I just start at the pump?

Take the hose off at the other end, what ever that may be, and run it in a bucket. I knew this was going to come up.

[atoll]

is the anti siphon between the seacock and the pump or between the pump and heat exchanger and exhaust,some work on suction(before) others on pressure after the pump.
if the former it could be it is letting air in

[Don1500]

Before anyone jumps, I made sure the coolant was replenished before starting the engine again. I have only run it about 1 minute to see if the pump was spitting. I was able to go right back to work on it since it didn't get hot. If the raw water system was completly drained how long would it take to start spitting again?

[Don1500]

Originally Posted by Ex-Calif

Make sure the impeller key is there, the impeller may also have a brass center that is separated from the rubber allowing the hub to spin and not the impeller.

Now that's something I didn't check, have to pull the impeller again! Glad I have the speedy change housing.


OK, pulled the impeller, again, the collar looks good and it will not turn. Now to put it back in.

BTW, this impeller is less than 2 months old. They put it in the day we did the sea trials before I bought the boat. The last one had a broken vane (we found the broken piece).