water pressure on a 88 85hp

djohnalyn

Seaman Apprentice
Joined
Apr 23, 2007
Messages
34
3 weeks ago I was getting a steady 14 psi at 4700rpm. THis past Sunday I was only getting about 9psi, but I was at 4900rpm...

Between the two attemps I ran the engine in my driveway with the muffs for a minute or 2. What happend was that I noticed my temp gauge wasnt getting any reading at all while on the muffs, so I killed the engine and readjusted the muffs to make the water flow properly through the engine.

Then, I went to crank her back up and the heat buzzer went off as soon as I put the key in the "on" position. SO, I let it cool for about 10 minutes, then cranked it back and everything seemed normal at idle speed (about 2psi)

Am I right to assume that I probably nuked/killed my impellar with this brief overheating...?

Who knows what the right PSI is for an 85hp in WOT range?(i'm guessing around 15psi)
 

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: water pressure on a 88 85hp

For a similar Merc that uses a similar pump, 4-7 @ Idle, 7-14 @ WOT. Your WOT RPMs are pretty low. You might have a powerhead problem, or you're way overpropped. The impeller will be damaged in less than a minute if starved of water.
 
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