How low is low for water pressure ?

F

fishfeatures

Senior Chief Petty Officer
Joined
Mar 29, 2011
Messages
743
After fitting a water pressure gauge to my motor as I had a slight overheat , so replaced the impeller just to be sure and also fitted a gauge. With the motor trimmed or tilted in shallow water, what PSI is ok for the engine when trolling along? Or so long as there is even 1 psi there's water going through the motor?

currently it's reading 6 @idle and 17 @ wot but I do troll on my river and sometimes end up in the shallows so jsut want to make sure I don't harm the motor if I have it tilted up high so I don't damage my prop.
 
C

Chris1956

Supreme Mariner
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Mar 25, 2004
Messages
27,142
Re: How low is low for water pressure ?

If it is a Merc, it sounds about right. A Johnnyrude would usually be higher.....What do you have?
 
F

fishfeatures

Senior Chief Petty Officer
Joined
Mar 29, 2011
Messages
743
Re: How low is low for water pressure ?

60 hp Johnny 1990. Now i have it tee'd off at the exhaust plate so i can still see the tell tale. I'll run it directly to the gauge so that there is no pee stream.
Any way what is the lowest PSI reading that will keep the motor cool, I'm thinking maybe 1-2 below idle reading??
 
Silvertip

Silvertip

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Joined
Sep 22, 2003
Messages
28,762
Re: How low is low for water pressure ?

If you are running that low a water pressure it indicates one of two things: 1) the water intakes are not fully submerged or 2) the impeller is going bad. There is no magic cool vs water psi number. You only know what normal is after replacing the impeller. Note the idle and WOT readings. Any deviation from those numbers indicates the impeller needs service.
 
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