Temperature Gauge
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Temperature Gauge
The temperature on the gauge is correct for about 10 minutes until the engine gets up to temperature. Then, the needle drops from the correct 180 temperature to 150 degrees. It stays on 150 degrees for about 5 minutes and then will occasionally bounce back up to the correct 180 degree temperature for about a minute before falling back down to 150 degrees. Does this sound like a problem with the sensor, wiring or gauge?
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Agreed, sounds more like a bad thermostat than a bad gauge. Perhaps the gauge is just fine and you actually have a problem. That's why we have gauges.
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From: Virginia
What year and engine?
First, I'd confirm with an IR temp gun (Harbor Freight, or Amazon, cheap and useful).
If you have a 77-82, I'd wiggle the connector in the back of the center gauge cluster, if you can reach it (easy with no glove box insert!).
First, I'd confirm with an IR temp gun (Harbor Freight, or Amazon, cheap and useful).
If you have a 77-82, I'd wiggle the connector in the back of the center gauge cluster, if you can reach it (easy with no glove box insert!).
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Thread Starter
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From: Virginia
The sensor isn't going to change resistance that quickly. A loose connection might.
77 still has the map pockets, right? Hopefully it's not back there.
What else happens when you get up to temperature? Do you have a bad engine ground? Is your alternator going on and off charge? Is your voltmeter showing anything wonky? Electric choke or other mods? Please post some photos!
77 still has the map pockets, right? Hopefully it's not back there.
What else happens when you get up to temperature? Do you have a bad engine ground? Is your alternator going on and off charge? Is your voltmeter showing anything wonky? Electric choke or other mods? Please post some photos!
Thread Starter
Team Owner
Joined: Sep 2000
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The sensor isn't going to change resistance that quickly. A loose connection might.
77 still has the map pockets, right? Hopefully it's not back there.
What else happens when you get up to temperature? Do you have a bad engine ground? Is your alternator going on and off charge? Is your voltmeter showing anything wonky? Electric choke or other mods? Please post some photos!
77 still has the map pockets, right? Hopefully it's not back there.
What else happens when you get up to temperature? Do you have a bad engine ground? Is your alternator going on and off charge? Is your voltmeter showing anything wonky? Electric choke or other mods? Please post some photos!
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From: Virginia
Is your AC compressor cycling when this happens? Electric cooling fans? I'm trying to think of other periodic loads that only occur when hot.
Last edited by Bikespace; Jun 21, 2024 at 06:44 AM.
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I don’t have an electric fan, and the erratic behavior of the temperature gauge needle happens with or without the A/C on. I am out of town and away from the vehicle right now, but as someone suggested, I am going to check my engine ground when I return. It acts like a ground problem that somehow gets worse with engine heat. The vehicle is 47 years old and quite frankly I never gave a thought about the ground or ever cleaning the ground. I will post the results after cleaning or replacing the ground wire. Gosh, without ever lifting a finger (except on the keyboard) am getting some great ideas on a possible diagnosis. Thank you all, and stay tuned.
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How did you make out with this ? I have a '82 (built in '81) 454 that does almost the same thing. My gauge doesn't have temp increment hash marks but reads Cold-to-Hot (C -to- H). When the engine starts cold, the gauge points all the way to Cold, when it warms up (I'd guess correlated to the thermostat opening) the gauge simply bounces around. In my case, it can't be a thermostat problem, because I've driven it 85+ miles with no over heating. (Slowly over time, I've noticed other gauges acting erratically when operating at full temp for a extended period of time)
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How did you make out with this ? I have a '82 (built in '81) 454 that does almost the same thing. My gauge doesn't have temp increment hash marks but reads Cold-to-Hot (C -to- H). When the engine starts cold, the gauge points all the way to Cold, when it warms up (I'd guess correlated to the thermostat opening) the gauge simply bounces around. In my case, it can't be a thermostat problem, because I've driven it 85+ miles with no over heating. (Slowly over time, I've noticed other gauges acting erratically when operating at full temp for a extended period of time)
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On my car, several years ago, I found that ground cable going green under the insulation. I replaced that ground cable and my charging system became more robust, and all kinds of little things suddenly became better.
Fairly inexpensive part that can help a lot!
Fairly inexpensive part that can help a lot!
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I am taking about The big battery ground on the passenger side. I cleaned up the metal at the connections and the temperature gauge stopped being erratic when the engine got warm. I found that the area is kind of “tight” getting to those connections. I had to try several tools to find one I liked for turning the connections.
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Sounds like a bad sensor. IF it was a short it would peg the pother way I believe.. It culd be a broke plastic board and its going open
Watch this and figure it out
Watch this and figure it out
Old Fart Pilot
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From: Spokane, WA
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I am taking about The big battery ground on the passenger side. I cleaned up the metal at the connections and the temperature gauge stopped being erratic when the engine got warm. I found that the area is kind of “tight” getting to those connections. I had to try several tools to find one I liked for turning the connections.
I am taking about The big battery ground on the passenger side. I cleaned up the metal at the connections and the temperature gauge stopped being erratic when the engine got warm. I found that the area is kind of “tight” getting to those connections. I had to try several tools to find one I liked for turning the connections.
The ground that goes from the battery to the frame is on the drivers side.
Dash panel ground is on the driver's door hinge pillar.
The engine ground I think the OP is talking about is on the passenger side going from the starter brace to the frame's engine mount arm.
Never hurts to check & clean ALL grounds
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3rd party jumping in here to hopefully clarify things...
The ground that goes from the battery to the frame is on the drivers side.
Dash panel ground is on the driver's door hinge pillar.
The engine ground I think the OP is talking about is on the passenger side going from the starter brace to the frame's engine mount arm.
Never hurts to check & clean ALL grounds
The ground that goes from the battery to the frame is on the drivers side.
Dash panel ground is on the driver's door hinge pillar.
The engine ground I think the OP is talking about is on the passenger side going from the starter brace to the frame's engine mount arm.
Never hurts to check & clean ALL grounds