Water Pressure & Temp Questions

[sidenberg]

1987 Force 125. Will hooking up a water pressure gauge to the telltale plug outlet give an accurate reading to determine if the water pump is working correctly? If so, what would be the proper PSI at idle and at WOT?

Using an infrared thermometer what would be the proper temp when pointing at the heads right below the spark plugs at idle?

 

[MostlyHrmlss]

Re: Water Pressure & Temp Questions

I can't think of a reason it wouldn't work. I have no idea what the working pressures might be, but from what I've read around here, a telltale aimed upward squirts a plume about three feet at idle and six feet at WOT. I prefer the telltale anyway: it's so simple, it can't possibly fail to do its job.

For temperature, I believe the stock thermostat opens at 143F, so I'd expect the external head temperature to be thereabouts, probably a bit warmer.

 

[sidenberg]

Re: Water Pressure & Temp Questions

Actually the stock T-Stat for the 125 HP is 110 degrees. My infrared read about 125 to 130 after about 5 mins at idle using the ears. I am still curious about the water pressure coming off the telltale plug outlet if anyone has any knowledge?

 

[roscoe]

Re: Water Pressure & Temp Questions

I've had water pressure gauges on my last 3 outboards, a 70 hp force, a 50 hp Merc, and a 60 hp Rude.

With a new impeller, all 3 had similar pressures, some variation, but only a couple psi.

at idle, 2-5 psi
at mid throttle, 8-11 psi
at wot, 12-15 psi

the highest readings were on the 50 merc

the lowest on the 60 rude.

Make note of your pressures, and watch for a change, either from a worn impeller, or from plugged water intakes.

Anything abnormal warrants further inspection.