Well... not really a rebuild. I started up the engine in the boat, and found not much cooling water coming out of the exhaust. It's an 11 hp, raw water cooled diesel engine, that I haven't had any significant problems with in the last few years. It leaks a little oil, but always starts, and runs well.
When no water to speak of came out of the exhaust, I shut it down and pulled the water pump. One vane on the impeller almost broken off, and another looking weak. Oops, I hadn't replaced the impeller in a couple of years.
I have the pump out of the boat, and have the spare impeller in hand. My question is: What kind of lube should I use? I'm not talking about the shaft or bearings, just the impeller in the brass casing.
I have Lubrtiplate water pump grease, but that is a lithium based grease that seems more like it should be used on metal to metal. I also have some swimming pool seal grease made for lubricating rubber and silicone fitting and valves. I'm thinking I want to go with the "rubber and silicone" lube to keep the impeller moving smoothly inside the case.
What think you?
Kevin
What does the engine manufacturer recommend? That's usually what I try to use.
I believe you've got it. I use silicone grease I get at the dive shop for mask, fins, etc. It also keeps my port gaskets from drying out. I use it on all of Seraph's rubber items, the bellows of the bilge pump exposed on the outside,etc.
While I would check with the manufacturer, I think the silicon grease you're planning on using is probably the right stuff.
Jabsco recommends a light film of water pump grease, specifically on the shaft and the outer surfaces of the impeller...
While we are talking raw water pumps...
Averisera has a Yanmar 9hp one cylinder diesel (thumper) that runs well most of the time. Sometimes it doesn't pump water after we have been sailing fast in heavy air. Since the boat is a bit tender we wonder if a vapor lock does not occur in the intake line. After sitting for a night in a quiet place the engine pumps water and the alarm is off.
Of course... this is intermittent and only occurs in dicey circumstances. (We leave the mainsail up most of the time as a counter to the overheating gremlin.)
We replaced the impeller this year. The "new" impeller the seller said was in place did have a fault at higher RPMs with the vanes not turning while the shaft did turn. It did look new so on our first inspection, we didn't change it. Finally: new impeller, one occurance only.
Sea story related to the water pump occurance.
We were sailing South in a strong North Easter with night, fog, rain, no one feeling chipper... you know the deal. The Cape Cod Canal is our lee shore. We are aiming for a 300 ft wide entrance with beach on either side and few navigational aids. The boat is going about 7 knots. Knowing we were close, we took the headsail down and lashed it to the foredeck. (harnesses are used day and night by us, btw). Started thumper and heard the alarm dimly in the roar of wind and sea. darn. Someone was on our side, though. The alarm came on just as the rain stopped and fog lifted. Dead nuts on the Morse Code A and right where we expected to be. Tied up in the tiny harbor at the entrance known as "Harbor of Refuge Marina." Missed last call at the Aqua Grill. Had a glass of red and turned in. Next morning, fired off thumper and proceeded without incident to our next harbor.
Coincidence or an answered prayer?
Thumper is getting pump upgrades anyway.
regards, Norman