An electric pump instead of the Jabsco impeller??

[Simi 60]

Originally Posted by Cheechako

.

In that 50 years of boating I have probably replaced 8-10 electric water pumps of various sorts. ....

As have I but none of the ones I have replaced have been magnetic centrifugal pumps which, the MD 30 that I mentioned is

Continuously rated and chemical rated for $150

[merrydolphin]

Originally Posted by Idaho

A bit off topic maybe - After an impeller shreds, how does one clear the bits and pieces out of the engine and other downstream parts?

The only sure way is to take the down stream parts off or at least to the point where you can inspect them. The small blockage points are usually the heat exchanger, oil cooler, and mixing elbow. Raw water doesn’t usually get into the block. Only coolant does. Often they collect at the entrance to the heat exchanger or what ever smaller opening comes first.

[merrydolphin]

That 4- 236 is a great engine. I put upwards of 15K hrs on mine and as far as I know is still going strong.

BTW. I am in the Pamlico area now. Where are you?

[pendragon]

IMHO Installing an extra electric instead of impeller pump, add a filter/strainer after the pump or a temperature sender on the exhaust side, is all a bit like putting a plaster on a festering wound.
You need to get to the source of the problem and that is monitoring the inflow of sufficient saltwater. hence any flow meter mounted directly after the primary raw water filter makes perfect sense.
And if you than could set the flow alarm to suit your engine S.W. minimum flow at idle speed is even better, so that in the case of a partial blockage, the alarm would sound.
I installed one like this on my 43hp engine. I got it from Marine electronics, best value for money
The alarm sounds at startup, until the engine gets sufficient flow. So far no problems...

[Icarus]

Originally Posted by Jolly Roger

Thanks again guys:

My initial question has been answered uniformly. i.e. an electric pump is not a good idea.

I don’t have a temperature alarm, but I do have an engine temperature gauge on the dashboard, from a sender at the back of the head. This is easy to read by the helmsman, and alerted us to the problem in the first instance.

The exhaust flow on my boat is not easy to see when underway, since it is well under the curve of the hull. You have to hang upside down over the transom to see it.

My three-cylinder Kabuto generator is also raw water cooled with a Jabsco impeller, which also flows into the exhaust, so it’s a bit difficult to know what’s what, when both are running.

Goboatingnow’s flow meter sounds like an excellent idea. Perhaps he could show us how to make one?

Also, Nuku34’s idea of a ‘snap switch’ sounds like a good secondary auditory alarm. Would it work on the cylinder head, near the temperature sender, which will rise in temperature quicker than the elbow, if the flow stops? (By the way mate, you may have seen a few of my articles in Boating New Zealand recently, but I’m still learning new stuff, after nearly 50 years of sailing).

Does anyone know where to get one of these in the US?

I will also fit whatever I decide upon on the genny motor.

Surly you can hear it when the exhaust runs dry and therefore no water is coming out of the exhaust.?
A hot water alarm is a good idea..

[Simi 60]

Originally Posted by pendragon

I installed one like this on my 43hp engine. I got it from Marine electronics, best value for money
The alarm sounds at startup, until the engine gets sufficient flow. So far no problems...

Interesting site.
Says all prices in US dollars yet shows them in NZ dollars.

[Searles]

Using a different pump will not solve the problem of a blocked inlet or clogged filter ,have successfully used 12 volt centrifugal pumps on gen sets in the marine application for many years ,some big commercial diesels have centrifugal seawater pumps not unusual at all ,two inlets with two strainers one each side of the keel plumbed into the pump is a simple way out and commonly used. On an commercial vsls .⛵️⚓️

[Simi 60]

Originally Posted by Icarus

Surly you can hear it when the exhaust runs dry and therefore no water is coming out of the exhaust.?
A hot water alarm is a good idea..

Or a $25 exhaust temp alarm
No holes to drill, no pipes to plumb into.

[nonav]

Your consideration for an external pump still does not solve the problem of a clogged/fouled through hull.

Stick to the engine’s pump, and add a sea water strainer, if you don’t already have one.

Sorry to hear of your troubles!

[s/v Jedi]

Originally Posted by col50

Great idea. Might have to clean the bowl occasionally to maintain visibility.

We sail in the Caribbean, Bahamas and Florida and all I did in 10 years is shake out the impeller bits and occasional fish hook, monofilament etc.

Originally Posted by Sailorman97

What did you use for the housing itself?

This one: https://www.defender.com/product3.js...=-1&id=3438541

[bleonard]

Had similar experience, ended with impeller blades thru the heat exchanger.
So added a screen basket filter in hose outlet from the raw water pump, and redirected water flow telltale’s from external transom into top of cockpit drains.
Now easy to monitor water flow, and if for any reason a pump impeller throws a blade then caught in the basket filter and easily seen.

[El Pinguino]

Originally Posted by Simi 60

Interesting site.
Says all prices in US dollars yet shows them in NZ dollars.

Something lost in translation methinks

It should read 'Free shipping (with)in New Zealand , $127USD'.

[Jolly Roger]

We have progressed well beyond an electric pump, which was my original inquiry, and most experienced respondents agree that a secondary filter, or a flow meter after the pump, or both, is the best precaution.
Here is the filter I just installed. If it reduces the flow, I will build an inside like Jedi’s.(#35). Anyone with a Perkins 4-236 can easily install one, on the transfer pipe from the pump.
There is also only one way to check if debris, not just pump bits either, has gone further into the cooling system, the pipes have to come off, (#32) and the various heat exchangers cleaned. While doing that you might as well descale the block as well.
JR

[Disailor]

I have a small filter (Shurflo SHU253-120-01) inline between the raw water pump & the engine heat exchanger. The one time an impellor vane broke off I fund it in this filter.

[RaymondR]

Originally Posted by Jolly Roger

We have progressed well beyond an electric pump, which was my original inquiry, and most experienced respondents agree that a secondary filter, or a flow meter after the pump, or both, is the best precaution.
Here is the filter I just installed. If it reduces the flow, I will build an inside like Jedi’s.(#35). Anyone with a Perkins 4-236 can easily install one, on the transfer pipe from the pump.
There is also only one way to check if debris, not just pump bits either, has gone further into the cooling system, the pipes have to come off, (#32) and the various heat exchangers cleaned. While doing that you might as well descale the block as well.
JR

You could have both the original mechanical drive pump and an electric pump piped in parallel and switched by a temperature switch.