Temperature Help
Thread Starter
Pro
Joined: Jan 2009
Posts: 519
Likes: 84
From: Kings Park NY
Temperature Help
Well finally after 18 months my 82 CE is back on the road, after one hell of an engine swap many many upgrades to everything. If feels great to be driving a C3 again I sold my 78 when my daughter was born due to $$ issues. I have noticed that the temperature gauge at idle stays at 180 and then when I start driving it shoots up to 240+ and then when I come to a stop the gauge quickly drops back to 180 and then stays there for the remainder of the day. I can start and stop several times and drive for an hour or so at 180 and everything is fine.
I replaced the sending unit on the head, cause I broke it on my CC dual exhaust install and it does the same thing. Now I’m stumped. Could the cooling system have air in it, I tried to squish the hoses when I filled the system to purge the air out and the car does not run at 240, if I check the intake, heads, radiator and several other places with a IR thermometer it’s well under 200.
Could the gauge be faulty
I replaced the sending unit on the head, cause I broke it on my CC dual exhaust install and it does the same thing. Now I’m stumped. Could the cooling system have air in it, I tried to squish the hoses when I filled the system to purge the air out and the car does not run at 240, if I check the intake, heads, radiator and several other places with a IR thermometer it’s well under 200.
Could the gauge be faulty
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Do you have the all of the front spoiler components intact?? Sounds like you may not be getting the proper air flow at highway speeds. I had an 87 Firebird Formula and I ruined the small air deflecting spoiler and thought it was no big deal until I got out on the highway..........it overheated badly but would cool down at idle and slow speeds. Put a new spoiler on and problem solved.
Race Director
Joined: May 2006
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Racer
Joined: Sep 2009
Posts: 437
Likes: 3
From: Alvin Texas
There is a little gremlin that lives inside the instrument panel of every '82, he pushes the temp gauge needle around to confuse the driver.
Check the oil temp, it parallels the engine coolant temp.
Read the willcox paper very well...good info.
Check the oil temp, it parallels the engine coolant temp.
Read the willcox paper very well...good info.
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
I'm confused by your issue. Does the temp gauge go to 240, then back down to normal after a drive? Once it gets back to normal temperature, does it ever go back up to 240?
It sounds to me like you have a sticking thermostat. I have two ways of measuring temperature in my C3 and both agree - the car gets warm (not 240 warm, but 210 warm) before it drops back to normal... if that is the problem, when you replace your thermostat, replace it with a fail-safe one (it fails open, not closed).
It sounds to me like you have a sticking thermostat. I have two ways of measuring temperature in my C3 and both agree - the car gets warm (not 240 warm, but 210 warm) before it drops back to normal... if that is the problem, when you replace your thermostat, replace it with a fail-safe one (it fails open, not closed).
Thread Starter
Pro
Joined: Jan 2009
Posts: 519
Likes: 84
From: Kings Park NY
The oil temp is around 100 +/- when the temp spike occurs. This may sound a bit weird but you know when a car runs hot like 240 + you can smell and even feel it. But it doesn't happen. I think the car is running at 180 all day long but the gauge just has that spike and then returns to normal for the remainder of my drive. I will read the Willcox document and try to figure this out.
Last edited by malicatasr; Apr 23, 2013 at 11:51 AM.
Racer
Joined: Sep 2009
Posts: 437
Likes: 3
From: Alvin Texas
I believe that there is an intermittent open circuit in the circuit that feeds the gauge. My 82 does the same thing, I have not chased the culprit down, I know it is not really 280* IR says 185*-195* sometime it registers right, I just ignore it. The oil temp is steady @ around 180*. 
Thread Starter
Pro
Joined: Jan 2009
Posts: 519
Likes: 84
From: Kings Park NY
bpassmore I try to ignore it too, but I just built a 5k motor and it's hard to ignore, it just drives me nuts. I guess I'm going to start with another new thermostat. Then maybe if it still happens I will start chasing circuits. 
Safety Car
Joined: Jan 2009
Posts: 4,000
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From: New York
It could be air , and you want engine water temps thats why it is in the head , I would not want it in the thermostat housing personally. Take cap off rad , start car and let it warm up and cycle to operating temp and add antifreeze mixed 50/50 to top it off.