tested hot engine without thermostat
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
tested hot engine without thermostat
Since I have had my engine broke in (1 week) it has been running hot. I am still learning about timing etc. but I believe it is pretty close right now. In the meantime I thought I would pull the thermostat and run the engine without it to see what happens. It worked. I think it will run all day at 195-200 degrees. which is basically straight up on the gauge. I believe the thermostat is a 180 but I never tested it. My assumption is that I have a faulty thermostat. What do you guys think.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
Was a new temp sender unit installed on the new motor?
Are you sure motor is actualy running hot? Use an infrared temp gun to check independantly of gauge in car. It might simply be the wrong temp sender unit for your gauge.
cheers
Are you sure motor is actualy running hot? Use an infrared temp gun to check independantly of gauge in car. It might simply be the wrong temp sender unit for your gauge.
cheers
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Since I have had my engine broke in (1 week) it has been running hot. ...
In the meantime I thought I would pull the thermostat and run the engine without it to see what happens. It worked. I think it will run all day at 195-200 degrees.
...
My assumption is that I have a faulty thermostat. What do you guys think.
In the meantime I thought I would pull the thermostat and run the engine without it to see what happens. It worked. I think it will run all day at 195-200 degrees.
...
My assumption is that I have a faulty thermostat. What do you guys think.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If you have NO thermostat in the system and the engine heats to 190-200F, why do you think it would run cooler if it had a 180F thermostat 'blocking' the flow of water through the system? The thermostat will only stabilize the water temp at its designed temperature [180F in this case] if the engine with no thermostat runs at cooler than 180F. You need to figure out why your system wants to run so hot with no stat in the system.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
If you have NO thermostat in the system and the engine heats to 190-200F, why do you think it would run cooler if it had a 180F thermostat 'blocking' the flow of water through the system? The thermostat will only stabilize the water temp at its designed temperature [180F in this case] if the engine with no thermostat runs at cooler than 180F. You need to figure out why your system wants to run so hot with no stat in the system.
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Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
be sure to drill a 1/8" hole in the thermostat so that you have a minimal amount of water flow and no air will get trapped in the system
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Sounds like your cooling system is maxed. Did you add a bunch of HP with the new engine? HP = heat. If so, it may be time for a bigger radiator and/or a high flow pump.
Get your engine dialed in first. If she's too lean and/or the ignition is retarded and/or there's vacuum leaking, she can run hot.
If it's still running hot, you may have to invest some pesos in a radiator and pump.
Good luck!
Get your engine dialed in first. If she's too lean and/or the ignition is retarded and/or there's vacuum leaking, she can run hot.
If it's still running hot, you may have to invest some pesos in a radiator and pump.
Good luck!
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Since I have had my engine broke in (1 week) it has been running hot. I am still learning about timing etc. but I believe it is pretty close right now. In the meantime I thought I would pull the thermostat and run the engine without it to see what happens. It worked. I think it will run all day at 195-200 degrees. which is basically straight up on the gauge. I believe the thermostat is a 180 but I never tested it. My assumption is that I have a faulty thermostat. What do you guys think.
If I were you, I'd move on to something else...
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Because the 180F unit would over heat the engine, the temps just keep going and I have to shut down. so I thought 160 might be better. I did check the 180 and it definitely was all open by 180. I think my answer is because I don't have the system pressurized. It is open to the atmosphere because i have the body off. This is what the guy at Napa told me. I am going to hook up the expansion tank tomorrow and see what happens. If so, then I didn't realize how important it is to pressurize the system.
If it was running 210 in summer, it would run 210 w/ a 160 or 180 thermostat.
No pressure evaps. the water.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
I think my answer is because I don't have the system pressurized. It is open to the atmosphere because i have the body off. This is what the guy at Napa told me. I am going to hook up the expansion tank tomorrow and see what happens. If so, then I didn't realize how important it is to pressurize the system.
Safety Car
Joined: Sep 2009
Posts: 4,964
Likes: 28
From: Pittsburgh PA
you say you have the body off?? so i assume there is no shroud? just a fan on the water pump? no air is being drawn thru the rad with this setup. i would def run the 160 thermostat, and put youre house fan in front of the rad when you run it
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
It's a quick test for the thermostat, I'd start there. Also agree that with no shroud airflow could be an issue.
Several of these points have been made, but as noted the thermostat does not regulate the temperature of the engine - if it runs at 195, then it runs at 195 and the thermostat has nothing to do with it. Once it's open, the temp is up to the engine
I wonder a bit about timing as well...possibly too advanced from the start/break-in?
Several of these points have been made, but as noted the thermostat does not regulate the temperature of the engine - if it runs at 195, then it runs at 195 and the thermostat has nothing to do with it. Once it's open, the temp is up to the engine
I wonder a bit about timing as well...possibly too advanced from the start/break-in?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
The thermostat does regulate the temperature of the cooling system, as long as the system will stabilize at a lower temp than the rating of the stat when there is no stat in the system. It's amazing how many folks have no concept of what the thermostat does or how it operates....
P.S. The SB engine was designed to operate at 180F; and its cooling system is designed to keep the engine cooler than 180F {otherwise, it couldn't function properly with a 180F stat}. The only reason it [now] runs at 195F is because that's the temp rating of the stock thermostat.
P.S. The SB engine was designed to operate at 180F; and its cooling system is designed to keep the engine cooler than 180F {otherwise, it couldn't function properly with a 180F stat}. The only reason it [now] runs at 195F is because that's the temp rating of the stock thermostat.
Last edited by 7T1vette; Sep 14, 2009 at 01:29 PM.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
The thermostat does regulate the temperature of the cooling system, as long as the system will stabilize at a lower temp than the rating of the stat when there is no stat in the system. It's amazing how many folks have no concept of what the thermostat does or how it operates....
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
That's what I thought and told him. He said that the pressurized fluid is more efficient at removing heat. I will see tonight because I will have it pressurized.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
No, no. The shroud is on and on right just as it would be in the car. No leaks through the shroud, the gasket on the shroud is right up against the radiator.