Over COOLING problem
Melting Slicks
Joined: Apr 2007
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From: NJ
Team Owner
Joined: Jul 2004
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From: Hartford WI
Burning Brakes
Joined: Aug 2010
Posts: 951
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From: Placerville CA
I must be missing something here. Everything in this situation shouts FAULTY THERMOSTAT. Why all this speculation about heater cores, hoses and sensors? The car heats up at idle and cools down when moving....it's the thermostat! I had this happen to me one time while winter driving in the Sierra -- all of a sudden the heater began blowing cold air and the coolant temp dropped like a stone. When the car was stopped everything heated back up. We all know that the temp difference between stationary and moving is huge on these cars.
Geez, how hard is it to slap a new thermostat in there?
But I like the idea of the Harbor Freight laser thermometer, just because they sound like fun. They are on sale right now in Sac for $29.99. Reckon I'll git me a new toy.
Geez, how hard is it to slap a new thermostat in there?
But I like the idea of the Harbor Freight laser thermometer, just because they sound like fun. They are on sale right now in Sac for $29.99. Reckon I'll git me a new toy.
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Joined: Jan 2011
Posts: 55
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From: Hampton VA
I have replaced the thermostat again. Same problem. Took the vehicle down and had the coolant system flushed and still have the same problem. Just got home and stopped and got the laser thermometer. Getting ready to get back at it at 2:20 pm today. Stopped and even showed the problem to the dealership here in Hampton and the mechanic is amazed that when you drive the vehicle it cools down. He said it was the thermostat too, then I showed him the receipt from the last 2 thermostats that I have changed in the last week. Pretty much eliminates a thermostat problem I think. I WILL POST THE RESULTS OF THE THERMOMETER READING HERE IN A LITTLE WHILE.
Freeze
Freeze
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Joined: Jan 2011
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From: Hampton VA
Ok
Here are the temperatures with the car idling until it is showing 190-200 degrees on the Temperature Gauge and Thermostat is definitely open and cooling fans operating/cycling as advertised:
1. Top Radiator hose from Thermostat housing to Radiator 180 Degrees
2. Bottom Radiator hose--167 Degrees
3. From reservoir into Heater core 170 Degrees
4. Heater Core output with fan for blower motor running on high 145 Degrees
Thermostat housing 180 Degrees
5. Heat out of vents 125 Degrees with vehicle idling
6. Heat out of vents with 2000 RPM for 3 minutes 148 Degrees
Then I take car out for drive and no heat out of vents after about 5 minutes on the road and Water temp gauge falls back to about 110 degrees on the gauge.
I am completely stumped. But thanks for the idea of buying the Laser thermometer. At least I know that everything seems normal will sitting in the driveway.The dog also goes nuts if i shine it on the floor and tries to attack the red dot. It is worth the laugh to watch that huge lab chase it around the floor.
Could water pump be going bad. I would think that this would cause and Overheat problem instead.
Freeze
Here are the temperatures with the car idling until it is showing 190-200 degrees on the Temperature Gauge and Thermostat is definitely open and cooling fans operating/cycling as advertised:
1. Top Radiator hose from Thermostat housing to Radiator 180 Degrees
2. Bottom Radiator hose--167 Degrees
3. From reservoir into Heater core 170 Degrees
4. Heater Core output with fan for blower motor running on high 145 Degrees
Thermostat housing 180 Degrees
5. Heat out of vents 125 Degrees with vehicle idling
6. Heat out of vents with 2000 RPM for 3 minutes 148 Degrees
Then I take car out for drive and no heat out of vents after about 5 minutes on the road and Water temp gauge falls back to about 110 degrees on the gauge.
I am completely stumped. But thanks for the idea of buying the Laser thermometer. At least I know that everything seems normal will sitting in the driveway.The dog also goes nuts if i shine it on the floor and tries to attack the red dot. It is worth the laugh to watch that huge lab chase it around the floor.
Could water pump be going bad. I would think that this would cause and Overheat problem instead.
Freeze
Last edited by Humfreeze; Jan 31, 2011 at 03:50 PM.
Race Director
Joined: May 2008
Posts: 10,742
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From: Manheim Pennsylvania
Take the temperatures at the same spots just after the drive with 110 deg. indicated, see what you get. I would think the water pump going bad would increase the temp. also. I have never seen anything like this. What is the ambient air temperature?
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Racer
Joined: May 2010
Posts: 315
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From: Central New York NY
Those temps sound about what I got when I was shooting the laser around. Is there a way you can drive to a spot (parking lot) so when it cools down you can jump out and shoot the temps right then? Yea, the cats and dogs really like to chase the red dot.
Racer
Joined: May 2010
Posts: 315
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From: Central New York NY
I can't think of anything that could be wrong except the thermostat. Did you buy the second thermostat at the same store? Maybe a bad batch? You could always put the thermostats in a pan of water and heat it up on the stove to see how they react to the water getting hotter. How about this for an idea. AC goes into max mode, heater core water flow shuts off, cold air pumps thru vents, rad fans turn on constantly turning everything cold. Other than something like that I don't see how it can be anything but the thermostat.
Burning Brakes
Joined: Aug 2010
Posts: 951
Likes: 3
From: Placerville CA
Remove your current thermostat altogether and see if anything changes. I suspect it won't. I'm inclined to agree with the "bad batch of thermostats" theory. Production runs tend to use components bought from the same suppliers, in this case the Ching Dong People's Thermostat Wax and Cat Food Factory #7.
Drifting
Joined: May 2006
Posts: 1,428
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From: Chewelah Wa
I am sure the thermostat idea has been nearly beat to death, but let me throw out my experiences, as I have dealt with many a cooling system issue with my 85. I had some issues with using a "fail safe" stat in my car. The fail safe is supposed to stick all the way open when it goes bad. There is a clip on each side that holds it all the way open. Whenever I would "pack" my radiator with fluid, the excess pressure would cause it to get hooked on these clips, causing the problems you are experiencing. Packing the radiator is when you rev up the engine with the cap off (the coolant level in the rad will go down a lot) and adding coolant, sealing the cap before letting it idle. This adds capacity, and takes care of any excess air. You might try this for grins. I cut the clips off of the fail safe. I do not know if you have one of these, if you do, poo can it. Also, is there not some kind of pressure bypass on the vette water pump? Maybe this has failed. I have heard some guys block that passage with silicone.......
Thread Starter
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Joined: Jan 2011
Posts: 55
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From: Hampton VA
Yes i did buy the fail safe thermostats twice now because they are a little more expensive and I thought might function better. I bought both from Autozone so maybe I will try the Napa store this time. It couldn't hurt i guess.
I really don't know about the by-pass on the water pump but I am ready to replace that too if it would solve this problem.
Man that 2011 Camaro SS is looking better and better all the time. It would go nice with my 68 Camaro SS i have under cover in my garage and Hell I would still have my 78 Vette.
JUST A THOUGHT
FREEZE
I really don't know about the by-pass on the water pump but I am ready to replace that too if it would solve this problem.
Man that 2011 Camaro SS is looking better and better all the time. It would go nice with my 68 Camaro SS i have under cover in my garage and Hell I would still have my 78 Vette.
JUST A THOUGHT
FREEZE
Last edited by Humfreeze; Jan 31, 2011 at 07:35 PM.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
This is some of the craziest stuff I have said. But weird problems call for equally strange solutions.
Couple suggestions.
1 - Get a thermostat that is not a failsafe unit. Get a standard LT1 stat. Make sure "O" ring gasket is in place and facing right direction of taper.
2 - Is that any way the hose configuration of the cooling system is connected wrong somewhere. Do the hoses go where they should be? You had a lot of stuff apart.
Couple suggestions.1 - Get a thermostat that is not a failsafe unit. Get a standard LT1 stat. Make sure "O" ring gasket is in place and facing right direction of taper.
2 - Is that any way the hose configuration of the cooling system is connected wrong somewhere. Do the hoses go where they should be? You had a lot of stuff apart.
Last edited by pcolt94; Jan 31, 2011 at 08:21 PM.
Le Mans Master
Joined: Jan 2006
Posts: 6,564
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From: Woodstock Georgia
[QUOTE=pcolt94;1576668182]This is some of the craziest stuff I have said. But weird problems call for equally strange solutions. Couple suggestions.
1 - Get a thermostat that is not a failsafe unit. Get a standard LT1 stat. Make sure "O" ring gasket is in place and facing right direction of taper.
QUOTE]
He has an L98, not an LT1.
Couple suggestions.1 - Get a thermostat that is not a failsafe unit. Get a standard LT1 stat. Make sure "O" ring gasket is in place and facing right direction of taper.
QUOTE]
He has an L98, not an LT1.
Race Director
Joined: May 2008
Posts: 10,742
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From: Manheim Pennsylvania
I checked the maintenance manual and the problem has to be in the thermostat somehow. Remove the thermostat and inspect the housing for areas that corrosion has removed metal. This housing is pot metal and corrosion just eats this material into power. Make sure there are no cracks or ruff areas that would allow coolant to bypass. Now I see that your using an aftermarket thermostat, check the flange area, make sure that it is thick enough and doesn't allow the thermostat to float in the housing (I suggest using a genuine AC OEM replacement). This problem was probably there before you replaced the heater core. Now that the core is solid the resulting internal pressure change and possibly a coolant flow increase has magnified the problem causing the thermostat to bypass. Another component that could effect the system is the radiator cap. The cap should regulate the internal pressure to 17 psi, higher pressures could cause the thermostat to open earlier that it should. Try operating the system with the cap in the pressure release position, caution coolant will boil at 212 degrees under atmospheric pressure.
Burning Brakes
Joined: Aug 2010
Posts: 951
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From: Placerville CA
Since this problem pointed to the thermostat from the beginning the fail-safe feature would seem to be the obvious answer.
A certain number of forum readers will, as usual, cry "foul" when the matter of inadequate cooling comes up, but the fact that even cognition-impaired thermostats think things are getting a little warm ought to indicate something. AFAIK, no thermostat ever owned a Corvette or was convinced by Chevrolet that the temps encountered in these cars are "normal" or that they were "designed that way." A fail-safe thermostat just sticks open when it senses an overheating condition -- so defenders of the 'Vette's cooling system can take up their arguments with the 'stat.
But don't bother with the reverse-flow theory. Larry has a crossflow.
A certain number of forum readers will, as usual, cry "foul" when the matter of inadequate cooling comes up, but the fact that even cognition-impaired thermostats think things are getting a little warm ought to indicate something. AFAIK, no thermostat ever owned a Corvette or was convinced by Chevrolet that the temps encountered in these cars are "normal" or that they were "designed that way." A fail-safe thermostat just sticks open when it senses an overheating condition -- so defenders of the 'Vette's cooling system can take up their arguments with the 'stat.
But don't bother with the reverse-flow theory. Larry has a crossflow.
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Joined: Jan 2011
Posts: 55
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From: Hampton VA
I am going to get an OEM thermostat and install it this week. The Radiator cap was replaced initial 1 week ago when I started changing thermostats. On the drive into work this morning I took several temp reading from the vents as I drove and the temps were around 85 degree air coming out of the vents at 65 MPH. I am going to take temp shot of all the hoses when I get home tonight.
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FREEZE
Race Director
Joined: May 2008
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From: Manheim Pennsylvania
I revisited you previous info. I forgot you already replaced the cap. When you install the OEM thermostat really check the housing and mounting flange out. Were running out of ideas.