Low Idle with Low Water Flow

[leegoldring]

Apparently very typical, my older 1963 merc sterndrive needs low RPMs in idle (e.g. 550) to allow pressure off of sliding clutch so I can shift [more] easily. But low RPMs in idle does not create enough flow to cool engine after a hard run. In gear and running temp stays at approx 125 deg, starts climbing when back in idle to a bit over 180 and sometimes keep climbing. New impeller, water pump is fine, water tube in bell housing been replaced, manifold passages are clear so no restrictions. Recommendations from some folks are (a) install a crank mounted raw water pump and thru hull (but not even 3/4" of clearance available b/t the harmonizer and the front enginemount - so that is out) or (b) install a washdown pump and regulator with thru hull. The later at this point seems like my only option. Here are a few questions for the members please:
1. Is the washdown pump the only reasonable (effective and not incredible expensive) option?
2. Engine is a Merc 160 IL6, can a raw water pump be mounted with the right bracket and be belt driven?
3. Can I use a washdown pump in addition to (as opposed to removing the impeller) the water provided by the drive - to activate when water flow drops and augment the flow in idle? I've though about this last option and seems like it would require a water pressure switch and some check valves.

Any ideas (other than get a new outdrive - I very much want to maintain the originality of this boat and other than not being able to put out enough water at idle and low RPMs - it runs very well - would be greatly appreciated.

 

[Bondo]

Ayuh,.... Just what is this old outdrive,..??

No shift switch to break the ignition,..??

Crack the throttle to 700,.... only go to "Idle" to shift,..??...

A wash-down pump sounds like a misguided idea to Me,.....

 

[leegoldring]

Thank for your comments Bondo. it's a 63 MC-1; no shift interrupt...

You are suggesting, exactly what I was thinking of trying this weekend:

Forget all the aux water supply ideas, and when I come in from a hard run on the lake and want to go to idle/stop (I usually stop to adjust my fenders and get lines ready, this is when the temp starts to rise...), pull back shifter to neutral detent, pull out the shift disconnect button on the side of the Morse control and push the throttle up slightly to 7-8 hundred RPM to keep the water flowing. When ready to shift, back to neutral detent, push button back in and go.