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Old 02-17-2020, 03:26 PM   #1
shew01
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Default 180 Degree Thermostat "Hunting"

When I purchased my car in August 2020, it did not come with a thermostat. As the colder weather hit, I noticed that the temperature gauge rarely moved above 100 degrees. So, while replacing the upper hoses (I have two upper hoses because the previous owner split the upper hose for a fitting to the temperature gauge), I added a 180 degree thermostat from Bratton's. The thermostat came with two bypass holes drilled in it.

Before installation, I heated the thermostat in a pot of water on an electric range, and my temperature gun indicated that it opened properly at 180 degrees. So, I think the thermostat is working properly.

However, now that the thermostat is installed in the car, the temperature gauge "hunts" between 170 degress and 190 degress. Is that "normal" for a thermostat?
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Old 02-17-2020, 04:22 PM   #2
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Default Re: 180 Degree Thermostat "Hunting"

Yes I think things are OK.
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Old 02-17-2020, 04:49 PM   #3
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Default Re: 180 Degree Thermostat "Hunting"

Probably OK as is. Could also try drilling a 3rd 1/8 inch bypass hole in the thermostat, sometimes lessens the amount of "hunting".


Also make sure the Thermostat is located on the end of the hose closest to the motor with the pointy part of the thermostat pointing toward the radiator. To keep the thermostat from migrating towards the radiator use a hose clamp to hold it in place.
Having it against teh radiator can cause hunting, and the coolant to run hotter.


If using the in hose adapter for a temp gauge probe, the probe will now be in the wrong place. You should get the outlet neck adapter so the probe is on the motor side of the thermostat.
https://modelastore.com/cooling-syst...3789&limit=100
https://modelastore.com/cooling-syst...=3791&limit=75


Another option is to use the Vintage Precision. http://vintageprecision.com/products...ing/index.html
If going his route, and using their thermostat - drill 2-3 1/8 in bypass holes in the thermostat.

Last edited by 30 Closed Cab PU; 02-17-2020 at 04:55 PM. Reason: Corrected link issue
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Old 02-17-2020, 04:59 PM   #4
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Default Re: 180 Degree Thermostat "Hunting"

Yes, I was going to say the temp probe is in the wrong place. It should be before the thermostat. I think that is why your temperature reading is hunting.

You could try moving the thermostat to the upper hose (after the probe) to check.
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Old 02-17-2020, 05:12 PM   #5
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Default 180 Degree Thermostat "Hunting"

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Originally Posted by 30 Closed Cab PU View Post
Also make sure the Thermostat is located on the end of the hose closest to the motor with the pointy part of the thermostat pointing toward the radiator. To keep the thermostat from migrating towards the radiator use a hose clamp to hold it in place.
Having it against teh radiator can cause hunting, and the coolant to run hotter.

That may be my issue. I didn’t want to disturb the temperature probe, and my thermostat ended up against the radiator.




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Old 02-17-2020, 05:20 PM   #6
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Default 180 Degree Thermostat "Hunting"

Is the probe in the correct place in my picture above? It is in the hose segment nearest the radiator.

The next time I change hoses, I would like to move to one of the hose outlets cited in the links above. Today, I was trying to stop an antifreeze leak with the least amount of effort. For whatever reason, It seems that one repair tends to lead to another, and I didn’t want to risk anything else breaking for the moment. ;-)

I’m guessing I’ll have to replace the temperature gauge on the next hose change as well. The probe is turning green where it hooks up to the fitting.


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Old 02-17-2020, 05:23 PM   #7
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Default 180 Degree Thermostat "Hunting"

If the probe breaks off the temperature gauge, there is no way to fix it, correct?


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Last edited by shew01; 02-17-2020 at 05:33 PM.
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Old 02-17-2020, 06:23 PM   #8
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Default Re: 180 Degree Thermostat "Hunting"

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If the probe breaks off the temperature gauge, there is no way to fix it, correct?


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No. It is a sealed unit. You will need to buy a new temperature gauge.

Sorry.
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Old 02-17-2020, 09:41 PM   #9
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Default Re: 180 Degree Thermostat "Hunting"

There are places that will repair that type of temp gauge.
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Old 02-17-2020, 11:06 PM   #10
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Default Re: 180 Degree Thermostat "Hunting"

I changed from the in line to the Vintage Precision Thermostat Housing and have been very pleased with the ease of instalation, operation, quality, looks and ability to change thermostat if needed. Something you may want to look into.


http://vintageprecision.com/products...ing/index.html
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Old 02-18-2020, 12:42 AM   #11
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Default Re: 180 Degree Thermostat "Hunting"

I bought the output pipe that has the fitting already drilled and tapped for a temperature gauge, and the T-stat is in the upper hose with the button facing the engine as close to the engine as I can get it. I drilled a couple holes in the T-stat.

I get very stable results except, there are times on cooler days going down a hill where the reading will go pretty low, but come right back up under any kind of load. I have a 160 degree and the only time it goes over that is on a hot day when even wide open, the cooling system would go over even with no T-stat in the system. With the new Brassworks radiator, it stays below 190 even on a pretty hot day. But, going back to non-extreme weather, I get real stable results with the set-up.
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Old 02-18-2020, 02:20 AM   #12
31 Vicky
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Default Re: 180 Degree Thermostat "Hunting"

I was only able to get the 185 degree thermostat to work correctly in a pressurized system. The 160 degree performed well in a non-pressurized system.

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Old 02-18-2020, 01:55 PM   #13
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Default Re: 180 Degree Thermostat "Hunting"

Quote:
Originally Posted by shew01 View Post
When I purchased my car in August 2020, it did not come with a thermostat. As the colder weather hit, I noticed that the temperature gauge rarely moved above 100 degrees. So, while replacing the upper hoses (I have two upper hoses because the previous owner split the upper hose for a fitting to the temperature gauge), I added a 180 degree thermostat from Bratton's. The thermostat came with two bypass holes drilled in it.

Before installation, I heated the thermostat in a pot of water on an electric range, and my temperature gun indicated that it opened properly at 180 degrees. So, I think the thermostat is working properly.

However, now that the thermostat is installed in the car, the temperature gauge "hunts" between 170 degress and 190 degress. Is that "normal" for a thermostat?
This may or may not be a solution for your hunting problem, but I would recommend that you switch to a 160 degree thermostat. It will help the engine warm up. The 180 may be too warm.

I have seen my 160 hunt and swing up and down a bit when the engine is warming up from cold. But once the temperature is up there, it is stable.
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Old 02-18-2020, 03:04 PM   #14
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Default Re: 180 Degree Thermostat "Hunting"

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Originally Posted by shew01 View Post
Is the probe in the correct place in my picture above? It is in the hose segment nearest the radiator.

The next time I change hoses, I would like to move to one of the hose outlets cited in the links above. Today, I was trying to stop an antifreeze leak with the least amount of effort. For whatever reason, It seems that one repair tends to lead to another, and I didn’t want to risk anything else breaking for the moment. ;-)

I’m guessing I’ll have to replace the temperature gauge on the next hose change as well. The probe is turning green where it hooks up to the fitting.


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With the style probe adapter you have, if the thermostat is properly placed against the motor coolant outlet neck, the probe temp. will swing every time the thermostat opens or closes, since the probe will be on the radiator no coolant flow side of the thermostat when the thermostat is closed.


Not sure where your coolant leak is . However the hose clamps are not tightened down properly which can cause leaks. They are on an angle compared to the hoses. The clamps should sit squarely on the hose.


Try changing to distilled water when trouble shooting/fixing these issues, then switch back to antifreeze when all is good.
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Old 02-18-2020, 03:13 PM   #15
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Default Re: 180 Degree Thermostat "Hunting"

Also if ordering the motor outlet neck, there are 2 different ones, dependent on the year of car/motor. The angles of the neck are different . You picture looks a little funky, as if the hoses do not align straight with the radiator neck. If not aligned, you may have the incorrect radiator/neck, or the incorrect outlet neck on the motor, which can cause difficulties in leaks.
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Old 02-18-2020, 04:22 PM   #16
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Default Re: 180 Degree Thermostat "Hunting"

I haven't run a thermostat in a model A but just blocked off part of the radiator with some card board when it got real cold.
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Old 02-18-2020, 06:52 PM   #17
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Default Re: 180 Degree Thermostat "Hunting"

move the temp bulb to the cylinder head outlet neck.
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Old 02-18-2020, 08:46 PM   #18
shew01
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Default 180 Degree Thermostat "Hunting"

Quote:
Originally Posted by 30 Closed Cab PU View Post
With the style probe adapter you have, if the thermostat is properly placed against the motor coolant outlet neck, the probe temp. will swing every time the thermostat opens or closes, since the probe will be on the radiator no coolant flow side of the thermostat when the thermostat is closed.


I probably wasn’t clear in my post. My thermostat is located adjacent to the radiator (i. e., at the top of the posted picture), not adjacent to the engine block (which would be near the bottom of the posted picture).

Granted, the traditional place to install a thermostat is as close to the engine block as possible, to measure the actual engine heat as accurately as possible. However, with my current probe configuration, moving the thermostat to the bottom of the top hose (i. e., closer to the block) would make the temperature gauge be even more inaccurate, wouldn’t it? Because that would put the probe on the “cold” side of the thermostat.

I’d want the probe on “hot” side of the thermostat, correct?

The hoses themselves are not leaking—they are dry. In the picture, there is a small drop under the center of the upper tank. The stop leak has (most likely temporarily) stopped that drip for now.


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