Bench Mark / Bench Test

Thank you John for the 400 GPH raw water pumping capacity figure,
of the 3GM30F, but wondering how you came upon this figure.
Did you find it in some literature, did you do a bench test of the
raw water pump, or did you start the engine, hang a bucket under the
exhaust and collect and record the amount of water, creating a bench
mark for future reference, as recomended by some?

Calliste’s 3GM30F at 1000 RPM, in gear, new engine, when cold, puts
out 283.5 GPH and warm engine puts out 553.5 GPH as measured by the
bucket/exhaust test.

But, because she has a small 1/4" necking down to 1/8" diverter
line just after the raw water pump, diverting raw water to cool the
teflon packed, shaft packing gland and to enhance water flow through
the cutless bearing , my above “Bench Mark” test will not be the
same amount for other 3GM30F’s.

Calliste also has a valve and hose from a mini sea chest before
the raw water strainer and raw water pump, which could be used for
bilge dewatering (slow as it is) , but it’s use so far, has been to
flush out the heat exchanger with fresh water before layup.

figure came out of the specs page in the shop manual for the engine. btw-i
met a boat in the bahamas this winter with a engine water cooled stuffing
box. after an uneventful trip down the icw undr power, they had sailedfrom
nassau to allens cay (~40 nm) with the prop freewheeling. it had overheated
and seized, the o ring seal holding piece was spinning in the rubber hose.
no way i could figure out to fix it there, and i think they needed to be
hauled.
john

dwkayaks@spiderweb.com.au wrote:

Thank you John for the 400 GPH raw water pumping capacity figure,
of the 3GM30F, but wondering how you came upon this figure.
Did you find it in some literature, did you do a bench test of the
raw water pump, or did you start the engine, hang a bucket under the
exhaust and collect and record the amount of water, creating a bench
mark for future reference, as recomended by some?

Calliste’s 3GM30F at 1000 RPM, in gear, new engine, when cold, puts
out 283.5 GPH and warm engine puts out 553.5 GPH as measured by the
bucket/exhaust test.

But, because she has a small 1/4" necking down to 1/8" diverter
line just after the raw water pump, diverting raw water to cool the
teflon packed, shaft packing gland and to enhance water flow through
the cutless bearing , my above “Bench Mark” test will not be the
same amount for other 3GM30F’s.

Calliste also has a valve and hose from a mini sea chest before
the raw water strainer and raw water pump, which could be used for
bilge dewatering (slow as it is) , but it’s use so far, has been to
flush out the heat exchanger with fresh water before layup.

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