Thermostat recommendation.

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Dan B.

78 and still going.
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Cold Spring, MN
Looking at changing my thermostat to a 160'. The one I took out looks to be made by Flowkooler Robertshaw? It is stamped 160' but the car runs way too hot at 200'. (i'm running twin electric fans). It has a 2.250' dia. flange. .035" thk. My intake is a Mopar M-1 single plane. Any ideas? Or, should I drill some holes in the one I took out for by pass?
Thermostat.jpg
 
The stock thermostat is 195. That's what I recommend.
 
I would go with 180 degrees, but running a cooler thermo stat won't fix the operating temp, that's up to the flow and air flow going thru the radiator my guess if your electric fan are not pulling enough air. Also is that a mr.gasket t stat?
 
Looking at changing my thermostat to a 160'. The one I took out looks to be made by Flowkooler Robertshaw? It is stamped 160' but the car runs way too hot at 200'. (i'm running twin electric fans). It has a 2.250' dia. flange. .035" thk. My intake is a Mopar M-1 single plane. Any ideas? Or, should I drill some holes in the one I took out for by pass?View attachment 1715372248



The thermostat is NOT your issue unless it's defective. 160 is pretty cold. I run at 170 but I run thin oil and have 11:1 compression.
 
Personally I hate electric fans. I had a flex 180 in my car and it ran OK but it would lean towards the warm side (200 -210). Scrapped it and put a 216 8 blade fan with a HD Hayden clutch and a 160 Robert Shaw therm. That was my ticket. Nice and cool on the hottest of days.
 
160° is usually the wrong answer. The thermostat sets the minimum engine operating temperature, not its maximum. Start reading here (advance to each next chapter at the bottom of the page).
 
160° is usually the wrong answer. The thermostat sets the minimum engine operating temperature, not its maximum. Start reading here (advance to each next chapter at the bottom of the page).
you have no idea how many times i've tried to explain that to someone, and they look at me like i drive a chevy
 
you have no idea how many times i've tried to explain that to someone, and they look at me like i drive a chevy

It's preached here on a regular basis, but people still think the thermostat controls hot how an engine runs. That's mainly the radiator's job. And thanks @slantsixdan for chiming in. I was thinking of coming back to tag you but I didn't have to.

I normally split the difference on thermostats and go 180* on my stuff, but most of the time, you see OEM thermostats above that.
 
IMHO.
1ST replace the thermostat what is called for by the manufacturer.

2nd as others have said if the engine runs hotter than the the thermostat you have a cooling issue. (Clogged radiator core, bad water pump, blocked water passages, pulley diameters not correct, fan not correct for the application, radiator not correct for the application, )

What engine, radiator, modifications, etc
 
during the worst part of the summer, i get to 180' by the end of the driveway.
i know your pretty far north, but 200' ain't anything
 
160° is usually the wrong answer. The thermostat sets the minimum engine operating temperature, not its maximum. Start reading here (advance to each next chapter at the bottom of the page).
Good article! But won't the higher heat cause dieseling?
 
IMHO.
1ST replace the thermostat what is called for by the manufacturer.

2nd as others have said if the engine runs hotter than the the thermostat you have a cooling issue. (Clogged radiator core, bad water pump, blocked water passages, pulley diameters not correct, fan not correct for the application, radiator not correct for the application, )

What engine, radiator, modifications, etc
The engine is a Magnum 360 (5.9L). I just installed a new aluminium BeCool radiator. Is it possible that there was an air pocket in the radiator when I filled it after installing new? Before the new radiator the notest it got was 190', now it climbs to 210-212'.... the problem i'm having finding another thermostat is the flange dia. I need a 2.250" dia. and all i'm finding is 2.500" or smaller.
 
Good article! But won't the higher heat cause dieseling?


No it won't cause dieseling. There are times when running cooler engine temps has a benefit. There is a reason why Pro Stock chill their engines before every pass.

But you have to run water thin oil. And a bunch of other stuff. There is a time and place for cool engine temps. This isn't one of them.

I know my cooling system has to have a thermostat. If it doesn't have one, it never gets over about 120 degrees. That's how every cooling system should be. You should need a thermostat to regulate minimum engine temp. If not, your cooling system is weak.
 
The thermostat temperature determines when coolant begins to flow out of the block, operating temperature will depend on several factors, including compression ratio, fuel quality, number of cores or rows in the radiator, also how many square inches of cooling area the radiator provides, air flow obstruction, water pump condition and volume, pulley size, belt tension, fan cfm, and when the fans are engaging, among other potential causes.
 
The engine is a Magnum 360 (5.9L). I just installed a new aluminium BeCool radiator. Is it possible that there was an air pocket in the radiator when I filled it after installing new? Before the new radiator the notest it got was 190', now it climbs to 210-212'.... the problem i'm having finding another thermostat is the flange dia. I need a 2.250" dia. and all i'm finding is 2.500" or smaller.


Google Stewart Components and call them. They have the size you need and make the best thermostat.

I doubt the air pocket deal.

Is the fan arrangement the same with the new radiator as it was with the old radiator.

I'll say it again...these old cars were never designed for electric fans and those shitty aluminum shrouds that do mostly nothing but block air.

Once you hit about 15-20 MPH the fan is in the way. If those electric fans and shroud are blocking air movement through the radiator, it will cause the engine temp to rise.
 
Google Stewart Components and call them. They have the size you need and make the best thermostat.

I doubt the air pocket deal.

Is the fan arrangement the same with the new radiator as it was with the old radiator.

I'll say it again...these old cars were never designed for electric fans and those shitty aluminum shrouds that do mostly nothing but block air.

Once you hit about 15-20 MPH the fan is in the way. If those electric fans and shroud are blocking air movement through the radiator, it will cause the engine temp to rise.

I agree w/ most all of these last posts , but in a lot of circumstances , it "is" beneficial to jack the front end of the car up when filling the engine and rad., I have even left them over night to let the air work out of them, especially if the top of the rad. is lower than the engine . <not many that way.
I have to raise my 68 fastback 440/505 to fill it -------------------
 
I agree w/ most all of these last posts , but in a lot of circumstances , it "is" beneficial to jack the front end of the car up when filling the engine and rad., I have even left them over night to let the air work out of them, especially if the top of the rad. is lower than the engine . <not many that way.
I have to raise my 68 fastback 440/505 to fill it -------------------


If the top of the radiator is lower than the engine then you can get air trapped. You can drill 2 or 3 .187 holes in the outer ring of the thermostat to help bleed the air in that case.

How is the top of your radiator lower than the engine??? Don't ever think I've seen that in a Chrysler.
 
Google Stewart Components and call them. They have the size you need and make the best thermostat.

I doubt the air pocket deal.

Is the fan arrangement the same with the new radiator as it was with the old radiator.

I'll say it again...these old cars were never designed for electric fans and those shitty aluminum shrouds that do mostly nothing but block air.

Once you hit about 15-20 MPH the fan is in the way. If those electric fans and shroud are blocking air movement through the radiator, it will cause the engine temp to rise.


The old rad. was also a BeCool. There is no shroud. The fans are the same, in back of the rad. and are governed by a controller. When I go looking for a thermostat they ask, what make, model and engine size? Doesn't matter, the engine didn't come in the car and the intake is not stock either. What does determine the size thermostat (not degree) is the Mopar M-1 single plane aluminium intake. (I do not know who made this particular intake). I've tried looking on line at the various thermostats to find one with a 2.250" od flange but no luck. My hope was to find someone who has a similar setup and could tell me what brand/kind they run.
 
The engine is a Magnum 360 (5.9L). I just installed a new aluminium BeCool radiator. Is it possible that there was an air pocket in the radiator when I filled it after installing new? Before the new radiator the notest it got was 190', now it climbs to 210-212'.... the problem i'm having finding another thermostat is the flange dia. I need a 2.250" dia. and all i'm finding is 2.500" or smaller.
The thermostat is most likely not your issue.
When does it get hot? At idle or at cruzn speed?
 
Stewart 180° : #301 is 2.125", #305 is 2.500", I think that's all they have. I think you can probably use the #301.

Mr. Gasket has a #4364 that is 2.120".
 
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