Failing Circulating Pump?

[Jmac572]

Hi everyone... The "Knot Working" really hasn't been working much at all this summer. In fact I haven't had a single trouble free day on the water since I took delivery of her in mid June. I have recurring issues that continue to stump the master technicians at Russo Marine in Boston. One of the newer issues is a LOUD squeal/chattering/bearing noise coming from the starboard side engine and while the engine rev's around the dock while using Axius. The squeal went away after they replaced the belt, but there is still a chattering/bearing noise right as the engine makes a cold start then I don't hear it anymore. Also the bilge has rust stain under the pulleys that has been getting bigger and is now in a linear form (almost like the water is slingshotting off the pulley). Here is a picture below, does this sound like a failing circulating pump?

 

[scoflaw]

rawwater pump bearing and seal assembly

 

[BillK2632]

Could be, they wear out, I have replaced mine. What will happen next is it will start leaking through the weep hole front bottom of the pump. The thing is looks like you have closed cooling, so if the pump is leaking I would expect to see coolant leaking out, not seawater. If it's seawater leaking in, check the raw water pump (bottom left), the dirty water spot is directly under it.

 

[CliffA]

you can buy a cheap 'mechanic's stethoscope' at most auto parts supply stores to help identify where the bearing noise is coming from.....

cliff

 

[JVM225]

Looks like rust or brown water stains. If that's what they are, Ali would suspect the raw water pump. The circulating pump should have anti freeze mix going through it so if that bearing were bad you'd see the antifreeze mix in the bilge.

 

[Jimmy Buoy]

I'd also say your raw water pump's seal has failed, allowing seawater into the bearings and ruined them. Remove the pump, take the back off to remove the rubber impeller and take the pump housing to a local machine shop. They can rebuild them relatively cheaply. After you get it back, put a new impeller and o-ring in and reinstall on the engine. If you find that the two ends of the impeller housing are badly grooved, you may want to get a rebuild kit from aftermarket marine which includes two stainless steel wear plates, rubber gasket, o-ring, new special sized rubber impeller to solve the wear issues in the old bronze housing.

 

[Jimmy Buoy]

Here's a look at the pump...

Note the grooves worn on the end cap (left) and the bottom of the housing (right). The stainless part seen in the photo is the one wear plate that will be dropped into the housing to provide a smooth surface for the impeller.

Next is the original impeller (left) which doesn't look bad at all, and the new "shorter" impeller to be used with the wear plate kit (if you have grooves worn in the bronze).

Hope this helps!

 

[Jmac572]

Ok awesome, thank you for the response guys. Much appreciated.

 

[mavrick86225]

I am having the same issue with my sea water pump. I do not have a closed cooling system. I have 350 MAG MPI Brovo 1 drive.

This may be a dumb question, but does the boat have to be out of the water to pull the Sea Water pump? I just don't know if I pull the hoses while to boat is in the water if I will take on water FAST!

 

[JVM225]

I am having the same issue with my sea water pump. I do not have a closed cooling system. I have 350 MAG MPI Brovo 1 drive.

This may be a dumb question, but does the boat have to be out of the water to pull the Sea Water pump? I just don't know if I pull the hoses while to boat is in the water if I will take on water FAST!

Not if you can close the seacock.

 

[BillK2632]

If you have a seacock then of course you can close it. Most Mercruiser outdrives use the raw water pickup through the outdrive which does not have a seacock. In that case yes, water is going to come in as soon as you disconnect the intake hose. On my old BIII I kept a plug (short piece of broom stick), shoved it in the hose and clamped it. Also if you can pull the hose back and raise it up above the water line. So short answer is yes you can change the pump while it is in the water, but be prepared to deal with stopping the water flow when you disconnect the intake hose.

 

[mavrick86225]

Thanks for the advice. My mechanic said the same thing. Keep the lines above the water line and bring a plug just in case.

 

[romanservices]

I had the exact same thing with my generator sea water pump - seal failed and rusted up the first bearing - pressed in some new bearings and replaced the seals for an easy fix.