454 Running hot

"Hey all. New to the site and

"Hey all. New to the site and hoping to get some advice on my boat.

I have a 98 Nordic sprint with a 454/ bravo 1 combo. I'm having a cooling issue. I changed the Impeller and put in all new autometer guages last summer. Used the boat 1 time. It is running just under 210. Never hotter. but I know that is way too hot. I just back flushed the cooler that is behind the Power steering pump, and just pulled the thermostat out. I boiled the thermostat and it started to open at 160 but was all the way opened at 190. Is that too long?

I'm also wondering if the guage is giving me the wrong reading. The new guages are Autometer but the sending unit is the original from Nordic. Could they read different?

Thanks for all the help. I'm just trying to cover everything before I put it back together.

Bill"

"very possible the sender unit

"very possible the sender unit and the gauge are not 'matched'. get the specs for the gauge (what the sender needs to provide to it, resistance wise) and post that info here.

you can also get an IR Temp gun and see what temp the t-stat housing is."

Bill

The temp sending unit

Bill

The temp sending unit produces a OHMS reading from ~80 ohms to ~240 ohms. I believe that 240 is air temp or ~ 75 degree. and ~80 equals 300 degrees. Just a guess as it could be the other way around. anyway if the Autometer guage is designed for this then you should be OK.

Is this a closed cooling system? with a heat exchanger? DETAILS DETAILS!!!!!

if NOT then your test of the thermostat should have had it opening at 145-150 degrees as I believe all raw (non closed cooling) are 143 thermostats.

Pull your sender and do the water heating test but start it when the water is cold and connect a ohm meter to it. watch the meter carefully and it should rise staedily and evenly as the water gets warmer. Red lead + to post in center of sender and black - lead to threads.

The thermostat also should have a number stamped on it.

What is it?

If there are no mods to the engine or anything else you may have left out of your boat description then you should never see temps above 180-190 max!

"240 ohms should get you the c

"240 ohms should get you the cold, marked side of the gauge, 110 ohms should be half way, and 33 ohms should be the hot, marked side of the gauge. These are standard sender values for a single station insturment panel."

Thanks guys. The system is fre

Thanks guys. The system is fresh water not a closed system. Thermostat is 160. My brother inlaw is down picking up a new thermostat and sending unit as I type. I figure the price is minimal as to a Blown head gasket. Now that I have talked to a few people I am pretty certian that the Sending unit is the Wrong reading.

make sure the new unit is comp

make sure the new unit is compatible with the gauge.....I think I've seen at least three different 'standards' across the different brands over the years and my sample size isn't large. (there's no economical way to change a sender's transfer function either!)

DO NOT use an automobile therm

DO NOT use an automobile thermostat. Boats should be run at 140-150 degrees. It sounds like thats what is happening. Go to the boat dealer in your town and they should have one for marine use.