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TellTale Water temperature

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DPForumDog

New member
When we go above 2200 or so RPMs our 1995 Mercury 150HP carb outboard the gauge moves toward hot. But when we put a thermometer under the tell tale water it is only 160 degrees. I read where 154 degrees is optimum temp for peeing water. Our water temp gauge sits at 75% if we are going a decent speed >2000 rpms. The needle moves toward hot. 8/10 but it is not pegged out. Seems to be running fine. Is this normal? Should we be concerned?
Thanks
Granny DP
DPForumDog
 
Picking up info on the www and via my son's 150 of the same vintage, you have a T stat in the top of both sides of your V engine and on the left side I think is the OT sensor and the right side is a ⅛" pipe plug for mounting a thermostat for dash display, or a water pressure gauge for dash display.

T stats on smaller engines, per the manual, seem to range from 100 to 143F for opening temp. OT sensor is around 195F. Above 2500 rpms (per the manual) the water pressure is such that it pushes the bypass Pop Off valve off it's seat allowing for higher, uncontrolled water flow for the higher cooling requirement.

In short, slow speeds look at stats, high speed look at Pop Off. On his engine there was a hose coming from the top rear, center of the block and went down to the bottom of the block to the location of the Pop Off. That's about all the help I can give you....since nobody answered your 3 day old post.
 
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