Temp Gauge Erratic
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Junior Member
Joined: Nov 2006
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Temp Gauge Erratic
My '99 Odyssey has 133,600 miles. After driving a few miles, the temp gauge reads to slightly below half then goes up to the red line but drops after a minute to slightly above half then goes up into the red area. This goes on until the rest of the trip. The scan tool shows a high reading of 242 dF - consistent with temp gauge and about normal at 180 -190 dF. I replaced the thermostat because it would half open at 190 and then fully close. The new thermostat was fully open at 190 dF. With the new thermostat installed the temp gauge still acted the same way as the old. I then experimented by having no thermostat installed and ran engine but I got the same results with a thermostat installed but the cycle was less frequent. Also, the coolant reservoir would not draw the coolant in when cold. It would only fill the reservoir above max line. I'm stumped. I will appreciate any help or suggestions....
Senior Member
Joined: Oct 2003
Posts: 875
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From: Buffalo, NY
First you have to see what the actual temp of the coolant is, if it's actually getting that high and the gauge reads correctly, then??
How does the temp sender look? Clean and tight? Battery connections clean and tight (I only say this because of grounding issues)? Maybe the gauge is just getting some intermitant signal from???
I'm not fimiliar with the Od's engine, but always check to make sure the electricals are working as they should. You may need a schematic to trace the signal from the sender to the gauge and see what it goes through like the ECU, cluster, dimmer switch, ground points etc, if anything.
How does the temp sender look? Clean and tight? Battery connections clean and tight (I only say this because of grounding issues)? Maybe the gauge is just getting some intermitant signal from???
I'm not fimiliar with the Od's engine, but always check to make sure the electricals are working as they should. You may need a schematic to trace the signal from the sender to the gauge and see what it goes through like the ECU, cluster, dimmer switch, ground points etc, if anything.
Junior Member
Joined: May 2005
Posts: 46
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Check temp on straight-aways
I had a bad head gasket on an old civic in college. The temp started reading high, but always cooled down on straight-away driving, since more air was passing over the radiator. Went back up when I stopped. Since I was so poor, I turned the heater on full-blast all year long to keep it running (the summers were heck!).
If it's not electrical, and you temp really matches the gauge, consider a bad head-gasket (as I recall, the color of your exhaust may change as well, since radiator fluid is getting above the pistons). Someone can chime in, but you might also consider a bad water pump or clogged up radiator.
William
98 Civic + 03 Pilot
If it's not electrical, and you temp really matches the gauge, consider a bad head-gasket (as I recall, the color of your exhaust may change as well, since radiator fluid is getting above the pistons). Someone can chime in, but you might also consider a bad water pump or clogged up radiator.
William
98 Civic + 03 Pilot