135 hp mercury black max power and temp loss

Zman1661

Cadet
Joined
Jul 7, 2017
Messages
7
Today was out on water and had a problem. I have a 18' searay w/ 135 hp black max. Everything was running great had been running for about 30 min and then started to lose rpm and power. I checked my gauges and my temp was all the way down and it normally runs at 160-170. Temp did come back up but now just no power. I thought it was strange that the temperature went all the way down. When problems started. And I've done a compression check all cylinders are 115 to 118.
 
Last edited:

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,158
Maybe your poppit valve stuck open? Obviously check the thermostats and poppit.
 
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