Electric water pump for genset

[gbillman]

I've looked for related posts, but can't seem to find any...so here's the question.

I do not get sufficient cooling flow through my 6.5 kw Kohler 6EK0D. At first I thought it was because of excessive run/lift (I was using the starboard head thru hull in my '06 Leopard 40 to feed the line that ran to the genset in the port forward lazarette). On a recent haulout, I added a dedicated thru hull in the port hull, bringing it closer to the generator (same lift). Still inadequate flow.

I am wondering if I should change to an external electric water pump. Has anyone made that modification? If so, how did you do it?

Thanks.

[wrwakefield]

The previous owner of our boat bypassed the built-in water pump on our 10kw Fischer-Panda generator [3 cylinder Kubota diesel] replacing its function with a spare 110VAC March pump [used for the raw water coolant loops for the air conditioning and refrigeration systems.]

The March pump is located below the waterline so it is self priming. It is wired directly to the gen [fused, but ahead of the generator feed breaker to the boat- so the pump gets power as soon as the gen is fired-up.]

He installed a Wye valve on the pump output; one side to the generator raw water circuit; the other overboard high on the freeboard as a vacuum breaker, flow validator, and flow adjuster. This valve is feathered to supply a majority of the flow to the generator.

Added note: The wye valve must remain partially open to overboard discharge in order to provide a vacuum break for the raw water feed line.

It has worked great the last 20+ years.

Unrelated, he also relocated the heat exchanger to outside the generator's acoustic housing so it could be replaced with a larger exchanger [and is more readily serviced... They were in the tropics at the time...]

In case any of this is of interest.

Cheers, Bill

[Turtle Blues]

Questions before you take major action.
Seems the corrections you made should have eliminated the problem if all components are functioning properly. Those pumps are pretty solid if the internals are in good shape.

What is the size of the through hull, strainer, and supply hose to the water inlet?
Believe the inlet is 3/4"? If that is the case 1" until you get there may be a minor upgrade but would check for other possibilities first.
Condition of the impeller, unrestricted water flow, has the exchanger been recently cleaned and chemically flushed?
Electric pump is possible modification but would exhaust all possible issues first. Hate to see you install it and still have a problem.

[SailingHarmonie]

Certainly the installation of a centrifugal pump will be more fussy about lift. They tolerate NO lift, they do not pull, they only push, but-with care-it can be done. You'll need to be 100% sure that the water pump cannot run if the generator engine stops.

BUT... it is VERY unlikely that the cause failure is in the size or design of the waterpump built into the generator. I am assuming that it is a standard flexible impeller pump?

Questions: How do you know you have inadequate flow? Have you measured it? If your generator is overheating there can be many causes.

Does the high exhaust temperature shut down the unit? Or the coolant temperature? Or both?

Does the shutdown always happen? or only under certain conditions? Does it ever work properly?

Has it had this problem since it was first installed or is this something new?

The impeller itself is in good shape? Has it been recently changed? When you inspect it, it is in good condition?