Temperature Gauge

[Watarski]

I have been having a problem with my temp gauge recently. After not having run the boat in a month, I took it out this past weekend twice. Both times after waiting for the boat to warm up, the temp gauge would go past the usual 158-160 degree mark and start to jump around a bit - then quickly bury itself at the max. After I shut it off and then on again, the temp would reset itself to around 170 (which is still higher than the usual). It's only 50 degrees outside, and it wasn't long enough for the engine to heat up that much (felt mildly warm). I'm wondering if this is a wiring problem and if anyone has had this issue before. I replaced my impeller last summer and have not run it out of the water since. Any help would be appreciated.

Thanks,
Craig

[skinautique]

It could also be an issue with the thermostat not opening quickly enough.

[yellowdog]

Inclinded to agree with the 'stat being the culprit. A thermostat trying to open and then failing would give the symptoms you describe. Sounds as if it hasn't failed completely, yet.

Did the gauge indicate an overheat condition the second time also or stay at the 170 temp?

Sending units normally fail open so you would not get any reading at all. Can't think of any wiring problem that would cause this condition. A failed gauge would indicate nothing or constant overheat.

[tryan]

if your boat has been laid up for a while, you will have air in the system. it will make the gauge go crazy and the thermostat won't open as fast with 140 degree air instead of 140 degree water.

are you open or closed cooling?

running off a hose will create enough pressure to jam the stat.

try this, go start the boat and shut it down at 130 or so. let it sit for 10 minutes to cool off to 100,just so the thermosat will close a tad. work it back and forth a couple times and it will start working. (i used to tap on the stat housing with a piece of wood.)

order a thermostat and a gasket, but you might not need it. get the right one 142 or 160 just whatever your boat is supposed to have. use hylomar gasket dressing on both sides of the gasket. (no scraping next time)

you could be sucking air from a loose clamp or bad strainer o-ring. or, as you stated, a bad gauge or connection. my stats (yes, two) stick all the time in the woody. i'll bet a dollar it's just air.

[tryan]

if the stat is stuck at 170 degree average opening, it will take forever to warm up. forever as in 15-20 minutes instead of 10.

[Watarski]

I appreciate everyone's input on this subject. Turns out it was the temperature sensor for the gauge. $9 part from skidim. Stupid question, and I think I know, but what is the difference between open and closed cooling?

Thanks again,
Craig

[Hollywood]

Open requires a water source (lake), closed has coolant (like an automobile)