Simple Raw Water Pump Question

[Ram]

Ive got a water pump">raw water pump leaking a little water,to me this would indacate the bearings are worn or could it just be the impeller?

[mike d.]

if it's leaking out the drip hole around shaft you will need to rebuild pump ie; shaft bearings and seal. with pump off (on a perkins/vovlo penta) it took me about 20 minutes to 1/2 hr.

[gbanker]

bad impeller should not cause a leak. more likely the shaft bearing/seal has gone. if you can afford to, buy a new pump and rebuild the old one and keep it as a spare.

[osirissail]

Post #3 is the best answer - having a spare complete raw water pump is very sensible. Especially with very old engines, the model raw pump get discontinued and trying to fit a new model can be a nightmare.

[shakey doug]

Your pump has a leaking seal this is generally mounted in the impeller side of casing between there and the bearing side a rubber slinger ring rotates on the shaft causing any leaking water to drop off stopping it entering the bearings on some makes there is also a seal to stop oil on timing plate mounted pumps leaking out. if buying a non-geniune seal replace STEEL expander ring with a 'o' ring also gives more tension if you have a dodgey shaft.

[shakey doug]

When pump is pulled down ie.no impeller ,spin shaft by hand if it feels smooth & no grumble noise the bearings are ok also check end float there should be none. post engine make etc for further details.

[Maine Sail]

I don't know what the pump is, brand wise, but most of them are of a similar design with some different variations on how they do seals, bearings and shafting.

It is likely the water side seal that has failed if that is what you are seeing..

Here's a tutorial on rebuilding a raw water pump:

Rebuilding A Raw Water Pump (LINK)

[MikeHachey]

I have purchased a sailboat with an 18 HP 2GM 1988 Yanmar diesel. It turns out that this engine is seawater cooled only - no heat exchanger. Can I take this boat to a salt water environment without destroying it?

[SkiprJohn]

Aloha Mike,
Short answer is yes! They were designed to do that.
regards,

[osirissail]

- - The old "Farryman" diesels with one lung-ers that are sea water cooled.

[mike d.]

if the boat has only been in fresh water why don't you add fresh water cooling to it and protect the motor. there are kits for around $500. or you can even go to a yard and see if you can pull one off an abandoned boat for short $

[osirissail]

Adding a seawater pump, heat exchanger and some hoses is a great suggestion. The oceans and seaways are not what they used to be and I would prefer to have some protection for the engine.

[Chief Engineer]

Do you mean more debris in the water of the chemical compostion of sea water?

Originally Posted by osirissail

Adding a seawater pump, heat exchanger and some hoses is a great suggestion. The oceans and seaways are not what they used to be and I would prefer to have some protection for the engine.

[osirissail]

Both plus mud. Inland and coastal waters are more acidic than they used to be. Galvanized chain looses its coating quite quickly. Acid water running through very hot diesel engines might do a nice chemical cleaning but that also means some to of the iron is disappearing.
- - Debris is not much of a problem as a good sea strainer will keep out stray logs, telephone pole and fish. But depending on how oftern the engine is run, barnacles larve, slime and sea grass can get past the sea strainer.
- - But mud is the big one. Most anchorages tend to be located at the outflows of rivers, which when a tropical rain storm occurs massive amounts of mud engulfs the anchorage. Over time the galleries in the engine become coated with more and more mud. I rebuilt a Ferryman and it was a trick and a half to get the mud out of the galleries.

[Mithril Bham]

I had an issue on my Lehman where the pump dripped from the faceplate. Replaced gasket three times. Replaced screws. Ended up being a leak from the lip seal. Was hard to see since pump was difficult to access. Finally rebuilt the pump and added a Super Seal which I love. Had to replace the pump shaft as well since it shattered on removal. Live and learn.