thermostat
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by ALLT4
I know, you see this a lot. I try to only offer advice on things I have REAL WORLD experience with and not spew second hand regurgitated here say as gospel.
You are spewing. Your experience does not apply to a gen-1 block like the thread starter or CFI has.
The common denominator I'm seeing in these thermostat threads is the LT1 guages read 10-15* above the tstat rating for some reason. Maybe the digital guage is off by design, or the digital guage sending unit is downstream of the thermostat. (The digital guage gets its signal from a different sensor than the analog guage right?)
My L98 reads about 5 degrees above the thermostat, when the tstat first opens.
Last edited by CentralCoaster; Sep 5, 2006 at 09:57 PM.
Melting Slicks
Joined: Dec 2004
Posts: 2,137
Likes: 5
From: Howard PA
What I'm saying is don't go around telling LT1 guys a 160 thermostat won't cause their temps to go down and stay down, because they will.
Several folks have confirmed this along with what is accepted as one of the best tuners on these forums. If folks say otherwise it's here say plain and simple.
The original poster DID NOT have his profile filled out when I made my comments. I checked before I spewed anything.
No one had any idea what kind of car he had when all this s**t started.
DO NOT tell anyone that a 160 degree thermostat WON'T cause an LT1 to run to cooler, because it will. I tried to make mine go to 190 tonight and couldn't do it, I let it sit there idling away and nothing more than 187 was read out. I'll make a freakin' video if you want to sit through something as boring as that. Hell I might even put the 180 back in to show you how it goes out of control in a second video and end all the here say.
I'll put my money where my spewing mouth is any day.
If you want to back peddle now and say we were only talking about L98's I call
Several folks have confirmed this along with what is accepted as one of the best tuners on these forums. If folks say otherwise it's here say plain and simple.
The original poster DID NOT have his profile filled out when I made my comments. I checked before I spewed anything.
No one had any idea what kind of car he had when all this s**t started.
DO NOT tell anyone that a 160 degree thermostat WON'T cause an LT1 to run to cooler, because it will. I tried to make mine go to 190 tonight and couldn't do it, I let it sit there idling away and nothing more than 187 was read out. I'll make a freakin' video if you want to sit through something as boring as that. Hell I might even put the 180 back in to show you how it goes out of control in a second video and end all the here say.
I'll put my money where my spewing mouth is any day.
If you want to back peddle now and say we were only talking about L98's I call
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
With your 180, did the engine run at 190-195? Where is the the sensor for the digital guage on your LT1? Why do the LT1 digital guage and analog differ?
Would you rather try to grasp all this by anecdotal experiences, or maybe actually try and understand how and why? I'm looking for answers, nothing more. If you don't care and would rather strut around saying you're right youre right youre right, then just say so, and I'll start placating you.
Would you rather try to grasp all this by anecdotal experiences, or maybe actually try and understand how and why? I'm looking for answers, nothing more. If you don't care and would rather strut around saying you're right youre right youre right, then just say so, and I'll start placating you.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Central Coaster, The reason the guage reads hotter then the t-stat setting is due to the reverse flow design of the motor. The water enters through the t-stat, picks up heat in the motor, and then the heat is measured on the guage. Remember, the guage measures the heat in the motor, not the set temp. of the t-stat.
As far as the 2 gauges reading differently, even the owners manual speaks to this. It basicially states the analog guage is for reference only. Latter on today, I can get the manual out of the car and give you the exact wording.
One other point to keep in mind. All t-stats have a split tempature built into them by design. For example, if you set your house t-stat on 70, it will let the tempature rise to 71, come on, and cool to 69, then turn off. This is called a 2 degree split.
I do not know what the split design is on a car t-stat, but I would expect it to be at least 10 degrees or more.
This too, will contribute to the engine tempature going higher then the t-stat design.
As far as the 2 gauges reading differently, even the owners manual speaks to this. It basicially states the analog guage is for reference only. Latter on today, I can get the manual out of the car and give you the exact wording.
One other point to keep in mind. All t-stats have a split tempature built into them by design. For example, if you set your house t-stat on 70, it will let the tempature rise to 71, come on, and cool to 69, then turn off. This is called a 2 degree split.
I do not know what the split design is on a car t-stat, but I would expect it to be at least 10 degrees or more.
This too, will contribute to the engine tempature going higher then the t-stat design.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by 93 ragtop
The reason the guage reads hotter then the t-stat setting is due to the reverse flow design of the motor. The water enters through the t-stat, picks up heat in the motor, and then the heat is measured on the guage.
One other point to keep in mind. All t-stats have a split tempature built into them by design.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Originally Posted by CentralCoaster
Thats what I thought too, until I saw that the guage sending unit is on the water pump right next to the thermostat. Correct me if I'm wrong.
Yes, this is hysteresis, the thermostat is slow acting. I have a hard time believing it takes until 195 for a 180 lt1 stat to open all the way. There has to be another explanation for it.
Yes, this is hysteresis, the thermostat is slow acting. I have a hard time believing it takes until 195 for a 180 lt1 stat to open all the way. There has to be another explanation for it.
Melting Slicks
Joined: Dec 2004
Posts: 2,137
Likes: 5
From: Howard PA
The gauge is on the head, the digital gauge is on the WP. Just unplug one or the other and you can confirm that. When we installed JakeCO3's 383 he broke the sender on the head and the gauge didn't work. I don't remember if it pegged or just sat there though.
For some further food for thought, my analog gauge if it's accurate, does read higher than the digital readout by about 10 degrees.
I explained why I think it happens but get knocked down so I give up.
The 180 degree thermostat maintains the temperature too high to start with. The cooling system can't cool enough on it's own at that starting point. Couple that with fans that are programmed to wait until things are way out of control and you have these threads.
You just have to get past that "minimun temperature" thing. What's supposed to happen sometimes in life just doesn't.
For some further food for thought, my analog gauge if it's accurate, does read higher than the digital readout by about 10 degrees.
Originally Posted by CentralCoaster
Would you rather try to grasp all this by anecdotal experiences, or maybe actually try and understand how and why? I'm looking for answers, nothing more. If you don't care and would rather strut around saying you're right youre right youre right, then just say so, and I'll start placating you.
The 180 degree thermostat maintains the temperature too high to start with. The cooling system can't cool enough on it's own at that starting point. Couple that with fans that are programmed to wait until things are way out of control and you have these threads.
You just have to get past that "minimun temperature" thing. What's supposed to happen sometimes in life just doesn't.
Tech Contributor
Joined: Jun 2004
Posts: 20,860
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by 93 ragtop
........ the reverse flow design of the motor. The water enters through the t-stat, picks up heat in the motor, and then the heat is measured on the guage.......
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Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by 69427
Not disagreeing, but I'm confused about how this system works. If I understand your statement, the cooler water from the radiator would flow past the thermostat, gather heat while circulating through the engine, and then exit back to the radiator. My first thought is that the thermostat would immediately close again after the "cool" radiator water passed by it. How exactly does this system work when the thermostat passes radiator water, rather than the warmer engine water? Like I said, not arguing, just trying to understand the operation of this. Thanks.
Check out this link as it does a much better job of explaining it then I do.
http://www.theherd.com/articles/lt1_cool.html
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
[QUOTE=CentralCoaster]Thats what I thought too, until I saw that the guage sending unit is on the water pump right next to the thermostat. Correct me if I'm wrong.
QUOTE]
Yes and no. The sending unit is in the bottom of the pump which is in the runner that is on the return from the head. I have an old pump that I opened to look at, and if you send me your e-mail I will take some pictures to show you what I am talking about. Meanwhile look at the link http://www.theherd.com/articles/lt1_cool.html and it does a much better job of explaining it then I can.
QUOTE]
Yes and no. The sending unit is in the bottom of the pump which is in the runner that is on the return from the head. I have an old pump that I opened to look at, and if you send me your e-mail I will take some pictures to show you what I am talking about. Meanwhile look at the link http://www.theherd.com/articles/lt1_cool.html and it does a much better job of explaining it then I can.
Tech Contributor
Joined: Jun 2004
Posts: 20,860
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by 93 ragtop
Check out this link as it does a much better job of explaining it then I do. http://www.theherd.com/articles/lt1_cool.html
http://www.theherd.com/articles/lt1_cool.html