Temperature gauge going up and dowm while driving
Thread Starter
4th Gear
Joined: Dec 2015
Posts: 4
Likes: 0
From: Tuttle, Oklahoma
Temperature gauge going up and dowm while driving
I have a 82 CE, just resently got my temperature gauge working. Replace the gauge and sending unit. Today, I replace the termostat. Check the fan clutch and it did not spin freely after turning the engine off. Don’t know where to go from here
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
How much of a temperature change are you seeing? If you are in hot weather and stop-and-go traffic, you should see temp changes as the cooling system tries to manage elevating engine temps. If it changes much more than 20 deg. F, you may have a temp sender problem. You didn't put any teflon tape on the sender threads, did you? The body of that sender MUST be grounded (part of the electrical circuit for the temp gauge).
Thread Starter
4th Gear
Joined: Dec 2015
Posts: 4
Likes: 0
From: Tuttle, Oklahoma
The termostat that I install is 195 deg. This morning did a coolant flow check and there was no fluid moving until the engine warm up. Drove the car this morning when the temperature was 70 and the gauge went up to about 230, them back down to 195. Try with the AC on and off, with the results. Not leaking any fluids. After returning home, check the return hose and it was not to hot to touch. Any suggestions.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
It is well known that the sending units are often times not correct and can react oddly. I had one that read 100 degrees Fahrenheit off.
It is possible that you could have an air pocket in the system IF your thermostat did not have a small hole drilled in it to allow the air to escape out of the engine while filling it up. .
If you filled up the system and did not allow the thermostat to open up and add more coolant.. You can be down low on coolant. Especially if you also did not put more coolant in your overflow reservoir so it can be drawn into the coolant system when the engine cools down.
DUB
It is possible that you could have an air pocket in the system IF your thermostat did not have a small hole drilled in it to allow the air to escape out of the engine while filling it up. .
If you filled up the system and did not allow the thermostat to open up and add more coolant.. You can be down low on coolant. Especially if you also did not put more coolant in your overflow reservoir so it can be drawn into the coolant system when the engine cools down.
DUB
Thread Starter
4th Gear
Joined: Dec 2015
Posts: 4
Likes: 0
From: Tuttle, Oklahoma
The old and new thermostats are doing the same issue. I’m looking at replacing the sensor and the connector. The shield around the connector is missing and is the original wiring connector. Does anyone know what the ohm reading I should be getting from the sensor?
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Race Director
Joined: Apr 2009
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From: Charlotte NC
Team Owner
Joined: Jun 2001
Posts: 23,379
Likes: 1,067
From: Virginia USA
Sounds like air in the system. Start it up with the cap off then wait until the thermostat opens by feeling when the top radiator hose gets hot (be careful of the fan). Rev the engine a little and watch the coolant level. I bet you'll see it go down. Keep adding coolant until it finally burps the air bubble out. That is achieved when the coolant level stays constant at the cap while reving. You may need a drip pan under the radiator because some will spill out when you let off the throttle. This may need to be done more than once so you'll have to let it cool off before checking the level again at the radiator cap.
I agree you should drill two 1/8 holes to allow air to be pumped out when the thermostat is closed. I always add as much coolant into the thermostat housing area in the intake manifold before installing the thermostat/hose connection housing. I also fill the upper radiator hose while holding it above the high point of the water system then quickly install it on the thermostat housing. A little messy but well worth keeping the air bubble to a minimum.
I agree you should drill two 1/8 holes to allow air to be pumped out when the thermostat is closed. I always add as much coolant into the thermostat housing area in the intake manifold before installing the thermostat/hose connection housing. I also fill the upper radiator hose while holding it above the high point of the water system then quickly install it on the thermostat housing. A little messy but well worth keeping the air bubble to a minimum.
Last edited by theandies; Jun 24, 2018 at 08:12 PM.
Racer
Joined: Jan 2008
Posts: 291
Likes: 15
From: Virginia Beach VA
I just went through this last week. It was an air bubble / low coolant issue in my case. I have a Vintage Air system and was able to drop the temperature for the drive home by turning the heat on (opens the electric water heater shut off valve). Just added coolant, got the air out, and all was well.