Water temp wacky - sender or gauge?

[markrinker]

Water temp on #1 is occasionally going into the red zone, then dropping back to what I expect is normal, then creeping up to 220, then dropping back to normal.

At first I was concerned that I had a cracked head - or worse. However, no coolant loss, no white exhaust smoke, engine seems to be normal temp when you pop the hood. Once I saw it 'peg' while idling at the pump, it became clearer that it was either the sender or the gauge.

Anyone experienced this? Which one?

[cruzer]

My Guess is sensor or wire grounding periodically. Its next to #1 cyldr.

good luck, Ken

[Dihrdbowti]

It's been awhile since mine did it but if you have a break in the wire the guage will peg to the red. If you have a short to ground it will always read cold. You can test the guage by pulling the lead off of the sensor, the guage will move to the hot side. The sensor is relatively inexpensive. I think mine was less than $20.

Hope this helps

[JohnC]

I've seen similar behavior when the water level is a little low, causing the thermostat to cycle a lot wider than normal. Also, sticking thermostat. Look at the sides of the plug for evidence of mechanical interference.

[markrinker]

I thought of the thermostat first, but the temp variances are too erratic even for that. Also - no apparent overheating under the hood, even when the gauge has pegged.

Thanks for the feedback, I'll look for the simple - probably a corroded contact at the temp sender due to road salt.

[markrinker]

Finally got around to troubleshooting this yesterday. The only temp sensor I can see is mounted on the '94 single t-stat water neck - on the top/front of the engine. Is this the only water temp sensor?

Unhooking it had no effect on the reading, the temp gauge remained pegged, well past the red zone.

[cruzer]

Gauge temp sender should be above #1 cyldr glow plug.

Ken

[markrinker]

Thanks, cruzer...