Temp gauge reading hot
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Joined: Sep 2005
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From: Colorado CO
Temp gauge reading hot
Hey guys,
I'm having problems with my temp gague reading hot. At first I thought I was overheating. I changed out everything I can think of from hoses to water pump and so on. The entire cooling system is new now but gauge still reading hot. The thing that puzzle me the upper hose never get hot. Any suggestions on what could be wrong. Thanks for the Help in advance.
I'm having problems with my temp gague reading hot. At first I thought I was overheating. I changed out everything I can think of from hoses to water pump and so on. The entire cooling system is new now but gauge still reading hot. The thing that puzzle me the upper hose never get hot. Any suggestions on what could be wrong. Thanks for the Help in advance.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
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From: Austin Texas
If the upper hose never gets hot, the themostat is not opening. Get an Infrared thermometer and read the temp. of the thermostat housing. The thermostat should open before 200 degrees. If the housing gets to 210-220 degrees and the upper hose is still cool, replace the thermostat or look for an obstruction in the cooling system. G/L 
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From: Colorado CO
Big G,
Thanks for the reply. I'm on my 3rd thermostat. New everything were could the obstruction be?
Thanks for the reply. I'm on my 3rd thermostat. New everything were could the obstruction be?
Originally Posted by big_G
If the upper hose never gets hot, the themostat is not opening. Get an Infrared thermometer and read the temp. of the thermostat housing. The thermostat should open before 200 degrees. If the housing gets to 210-220 degrees and the upper hose is still cool, replace the thermostat or look for an obstruction in the cooling system. G/L
Race Director
Joined: Nov 1999
Posts: 10,643
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From: Foxfield CO 1970 Convertible
Any chance the system is not completely full? If you've got air in the system, the pump won't be circulating fluid which will cause it to overheat. The upper hose would be empty in this case. I'd keep checking fluid level and topping it off...
Just a thought...
Just a thought...
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From: Colorado CO
Z-Man
Thanks for the input I thought I was pretty sure it was top off full. I'll check again. A quick note without the thermostat the gauge read low. that lead me to believe the thermostat was not doing it job. After three of them it still read hot. Am I missing somthing???????
Thanks for the input I thought I was pretty sure it was top off full. I'll check again. A quick note without the thermostat the gauge read low. that lead me to believe the thermostat was not doing it job. After three of them it still read hot. Am I missing somthing???????
Originally Posted by Z-man
Any chance the system is not completely full? If you've got air in the system, the pump won't be circulating fluid which will cause it to overheat. The upper hose would be empty in this case. I'd keep checking fluid level and topping it off...
Just a thought...
Just a thought...
Le Mans Master
Joined: Jul 2005
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From: Austin Texas
Originally Posted by ltlevil
I've said this before and I'll stick to it, check the gauge FIRST. Use a thermometer in the radiator and compare the reading to the gauge.
ltlevil
ltlevil
Le Mans Master
Joined: Feb 1999
Posts: 8,351
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From: Tampa Bay FL
Found the sender had failed after I installed rebuilt 882 heads. In interim, I installed a mechanical temp gauge underhood so that I could be assured all was fine while I was working to fix the problem. Installed a new sensor from Dr Rebuild if I recall correctly and kept the chrome gauge underhood mounted to where the TH350 trans vacuum relay once mounted on the firewall (had to put something there). Later, I purchased and installed DART heads having a different size thread for sender, I relo'd the gauge sensor to the top front of the intake (under the hose that connects to the thermostat inlet) on the two passages that get fluid from the heads and installed a plug in the cylinder heads. Current location probably isn't the best location on the intake given the potential to get low readings if a hose bursts or similar problem occurs but solved my need for sensor location.
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Le Mans Master
Joined: Jun 2002
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From: I can walk to MA
Stupid Q - but are you installing the thermostat with the copper
slug pointing down ?
If pointed up (toward hose) ...this would cause higher temps ... but it
should still open (eventually) and get the upper hose hot.
That - or the radiator is plugged - but you proved that's not so
after running with no T-stat.
Good Luck
slug pointing down ?
If pointed up (toward hose) ...this would cause higher temps ... but it
should still open (eventually) and get the upper hose hot.
That - or the radiator is plugged - but you proved that's not so
after running with no T-stat.
Good Luck
Burning Brakes
Joined: Apr 2004
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From: Des Allemands LA
Originally Posted by big_G
Read the post....upper hose not getting hot. The system holds about 4 gallons total. How much did you put in? What did you change in the past that might have led to this problem? Or did it just read hot one day?
At first I thought I was overheating. I changed out everything I can think of from hoses to water pump and so on. The entire cooling system is new now but gauge still reading hot.
Big G-I take it you are assuming the bottom hose is hot? Where does the post say the bottom is hot?
Is the bottom getting hot? Also what is "hot" in degrees? Did you take the thermostat out and try this? The other reason for the thermometer is you can actually see the flow of coolant, this kind of gives you an idea of things like the thermostat being closed or rad stopped up.
ltlevil
OK in my ranting I didn't see the part about running with no thermostat, however I'd still like to know the degrees the motor is running. Is it trying to boil over or does it appear to be hot or just the gauge says it's hot?
Last edited by ltlevil; Jan 26, 2006 at 05:48 PM.
Thread Starter
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From: Colorado CO
Ok guys lets shed some light on some of the questions. Before I do that thanks for all of the inputs. Ok the Temp gauge read red line. So I thought it was the thermostat. After changing out the thermostat the gague still read the same. So from there I changed out the water pump and hoses. Still didn't work. So I took the vette to a shop and they told me the radiator was clog and needed a new one. So taking there advice I bought a new one. So after all of that changing out everything stated including 2 more thermostats still didn't work. I tested the thermostats by boiling them in water to see if they opened. Which they did. So I'm at a loss. more help please
PS the lower hose does get hot.
PS the lower hose does get hot.
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Joined: Sep 2005
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From: Colorado CO
NH,
That is a good question. Yes, it going the right way. There are no stupid questions. Thanks
That is a good question. Yes, it going the right way. There are no stupid questions. Thanks
Originally Posted by NHvette
Stupid Q - but are you installing the thermostat with the copper
slug pointing down ?
If pointed up (toward hose) ...this would cause higher temps ... but it
should still open (eventually) and get the upper hose hot.
That - or the radiator is plugged - but you proved that's not so
after running with no T-stat.
Good Luck
slug pointing down ?
If pointed up (toward hose) ...this would cause higher temps ... but it
should still open (eventually) and get the upper hose hot.
That - or the radiator is plugged - but you proved that's not so
after running with no T-stat.
Good Luck
Burning Brakes
Joined: Apr 2004
Posts: 847
Likes: 0
From: Des Allemands LA
Did you recently pull the intake or do any other work prior to this happening? Another thought and this is just a thought because I am not sure what would happen-but when you got the new water pump are you certain it was the right one and not a reverse flow for a serpentine setup? Big_G does have a point with the airpocket thing, just seems like it would have worked it's way out by now.
ltlevil
ltlevil
Intermediate
Joined: Sep 2005
Posts: 28
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From: clearfield ut.
gauge reads hot
Hello,I had same thing happen to me after doing some intake work on my C-4.Temp. gauge was over 220,my aux.fan came on at 200 degrees.But main fan failed to run at 180 as usual.Top hose was cool,and engine didn't seem hot as temp. gauge indicated.I cracked open radator cap and coolant boiled out.After doing this about five times,engine let out a big gurgling sound and coolant went down low in radator.After adding coolant things went to normal.
Your fix seems more complicated than mine.But I hope this might help.
Your fix seems more complicated than mine.But I hope this might help.
Safety Car
Joined: Jul 2002
Posts: 4,269
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From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Does the gauge redline as soon as you turn the key on or does it creep up there after it warms up? I'm thinking bad gauge or sender here, pretty common in these sharks, and correct senders are difficult to find. You really need to measure the temperature of the coolant with an accurate thermometer as others have said
