Impeller Question....

[gbanker]

After a little over a year in service 134 hours of use I am about to change the impeller on my Northern Lights generator.

What, if anything, should I lubricate the new impeller with so that it doesn't burn up before it initially picks up water?

Thanks

[delmarrey]

Silicone spray.

For winter storage it's good to pull the impellers and spray them with silicone to preserve them in storage.

[Hydra]

Some impellers (don't remember the brand) for my Nanni engine are sold with a small tube of glycerine.

Alain

[Captain Bill]

Good luck, the problem is seawater washes off just about any lubricant you can put on in a few hours. I've got the same issue on my Onan. It sits about 3 feet above the water and about a 10ft hose run from the seacock. I've thought about putting a check valve in the line so that some water is pulled in fairly quickly but I'm concerned that might restrict the flow. In the meantime I keep a supply of spare impellers handy, the last one only went 75 hours.

[NCboatrx]

Captain Bill. You dont need a check valve and this may hurt the water flow. Just use a longer hose and put a loop just before the pump to hold water when the genset is not running. This helps the pump keep prime and lengthen impeller life.
Lubricate impellers with vaseline or silicone spray.
Johnson impellers come with glycerine lubricant.
My experience shows that regular vaseline actually outlasts the other lubricants on impellers and it is cheaper too.

[doug86]

Rub liquid dish soap on the vanes before pushing the new impeller into the pump, it makes impeller installation easier and keeps things slippery until the water reaches the pump. A dab or silicone grease or Vaseline is fine too.

[David M]

Do not use petroleum based lubricants like Vaseline on a rubber impeller or any rubber for that matter. It can cause the impeller and the O-ring to swell. And an O-ring that has swelled will never fit into its groove.

Use silicon grease. The impeller will go in like a greased pig. If you don't have a Grainger or a McMaster-Carr account then dive shops sell overpriced little containers of silicon grease.

On boats, silicon grease is also great for displacing water in electrical connectors. It will never adversely affect the rubber or plastic insulation nor cause a short.

[DotDun]

Originally Posted by Captain Bill

Good luck, the problem is seawater washes off just about any lubricant you can put on in a few hours. I've got the same issue on my Onan. It sits about 3 feet above the water and about a 10ft hose run from the seacock. I've thought about putting a check valve in the line so that some water is pulled in fairly quickly but I'm concerned that might restrict the flow. In the meantime I keep a supply of spare impellers handy, the last one only went 75 hours.

FWIW, My genset is Mase and sits ~22" above the water line. Mase suggested a check valve in the raw water line, which I installed. 450 hours and no problems. It is nice that I can clean the strainer and the system doesn't drain (check valve is above the strainer).

[Mardav]

Originally Posted by David M

Do not use petroleum based lubricants like Vaseline on a rubber impeller or any rubber for that matter. It can cause the impeller and the O-ring to swell. And an O-ring that has swelled will never fit into its groove.

Use silicon grease. The impeller will go in like a greased pig. If you don't have a Grainger or a McMaster-Carr account then dive shops sell overpriced little containers of silicon grease.

On boats, silicon grease is also great for displacing water in electrical connectors. It will never adversely affect the rubber or plastic insulation nor cause a short.

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You don't have to buy it at dive shops. Pool supply stores (or the pool supply section in the big box stores) sell the silicone grease to use on the pump strainger O rings. It comes in small 'tubs' and is very inexpensive. As stated it protecs electrical connections very well too and is not easily displaced by salt or fresh water.

[Alecadi]

Use blue propylene Globe impeller
They support much more harm than anything else.

[Captain Bill]

Some very useful input, thanks everybody. I do use silicone grease when assembling my impellers. It certainly lasts longer than some other lubes, but eventually the sea water wins. If it didn't I'ld use it as antifouling on my props.