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Raw engine cooling is there a better way than impellars

D

direstraits

Member
"hi i have a small diesel inbo

"hi i have a small diesel inboard Yanmar 1gm10 it has a raw water cooling system what seems to be a weakness is the waterpump impellar,there must be a better system and these impellars break and get a set and possible engine seizure due to overheat as it almost happen to me,i would like to design or better adapt to a crank mounted pumpi was looking at my old seagull outboard and they have a plastic water wheel that doesn't even contact the pump body,i also pulled apart a washing machine and again a better system.also pulled apart a bilge pump and that had a hard plastic/nylon wheel and this makes no contact with the sides and pumps 1400 gallons an hour.oh and a new impeelar from yanmar is approx $80 here in new zealand and they state with this model there is no aftermarket impellar"
 
"There are several crank mount

"There are several crank mounted pumps I've seen on the gasoline engines and most have reliability issues.

You could consider a keel cooler if you rig would support it. If you have a yard do it, it may not be too cost-effective."
 
hi the seagull outboard doesn&

hi the seagull outboard doesn't have impellar issues as they are made from plastic and don't contact anyserface and the bilge pump i dismantled after being told it was stuffed by a marine electrian also had a plastic impellar which does not contact ant surface but pumps a lot of water the raw water pump has a rubbery impellar that when stuffed back in pump body the little arms are bent and stressed and are always under compression which equals stress which equals early failure and can take a diesel out with it which equals stress and money there must be a better way i mean people have landed on the moon and seagull outboards for invented pre ww2 for gods sake just don't be a consumer
 
"I hate to bring facts into th

"I hate to bring facts into the discussion, but the difference between a centrifugal pump and a rubber impeller pump mean a lot. Your bilge pump works on centrifugal pressure, it's immersed in the water and so it needs no "sealing" against the pump body.

A rubber impeller pump seals against the pump body so it can pull water up to it when the water is not at that level. The rubber impeller actually creates a vacuum to suck water into it.

Different kinds of pumps for different purposes. If your Yanmar engine is below the waterline and water will flow into the pump you might get away with a centrifugal pump. If not, you might be wasting a lot of time and money trying to make it work.

Maybe you should spend the time figuring out WHY you're having trouble with the rubber impeller pump. Many people use them for decades with little or no problem. Are you beaching the boat and sucking up sand and debris? Boating in shallow water where sand is stirred up?

I boat in the PNW and routinely get 10 years or more out of rubber impeller pumps. Cold clean water, with no debris. My impellers get run at least every couple of weeks year around so they never take a set."
 
"Nothing wrong with bring fact

"Nothing wrong with bring facts to the table, at least on my end. Thanks for the inputs."
 
"Rubber impellor is postive di

"Rubber impellor is postive displacement technology, similar to automobiles' oil pump. In simpler terms, it'll always pump, irrespective of RPM's.

Centrifugal is constant RPM pump and does noy always guarantee good pressure & circulation.

Most marine motors have intricate and narrow waterways, hence impellors. I'd look at the pump housing for scoring, could be chewing up the impellor prematurely?

Then, these pumps that are rated at XXXXX GPH, they do not like to run for hours on end and don't take to back-pressure well.

Rather keep the rig as original as possible, you'll have a reliable motor in the end."
 
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