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tgump
05-23-2011, 10:53 AM
We launched our boat (1990 Prostar 190) for the first time this weekend and noticed that the temp gauge didn't work. I ran it for about a half hour around the lake and it never got above 120. I felt the hoses and they were cool. Could the thermostat be stuck or need replaced? I don't want to take a chance on damaging the engine. Any ideas??

Kyle
05-23-2011, 11:12 AM
Check the wire running to the temp sender on the intake manifold make sure it's not damaged or shorting and is connected to the sender. Since the guage starts at 120 and never went up the thermostat is more than likely not the issue. At normal operating temp 160 they open and start recirculating water through the block.

I would disconnect the wire off of the temp sender. Make a jumper wire to the oil sender and start the boat. The oil sender will send current to test the gauge as it will move or peg out. This will tell you if the guage or sender is bad.

I bet it's the sender is bad. And if you have an old tstat I would get a new one and gasket as a safety measure. I always replace mine every few years.