Thermostat opening and closing to much..

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Italianwagon

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Replaced water pump, fan clutch, radiator, thermostat and other Cooling system accessory’s. Took the 350 suburban out for a drive and the thermostat was opening and closing every mile or so. Is this to ofthen to be heating up and opening.? Didn’t do that before replacement,.

Air in the system.? Thoughts?
 

AuroraGirl

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Uh.. unless your truck is staying too cool I dont see the issue. Do you mean you see the gauge move more often? Being more sensitive to temperature and keeping your engine at a specific temp more precisely doesnt seem like a bad thing to me.
 

AuroraGirl

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Replaced water pump, fan clutch, radiator, thermostat and other Cooling system accessory’s. Took the 350 suburban out for a drive and the thermostat was opening and closing every mile or so. Is this to ofthen to be heating up and opening.? Didn’t do that before replacement,.

Air in the system.? Thoughts?
Also, you now have a more EFFICIENT cooling system with a new radiator, fresh coolant, a new water pump with no buildup or debris, a thermostat with no restrictions, etc. This could be helping your truck keep its temp much more quickly than your old cooling system. just a thought
 

84 M1008

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Could be air bound, but you probably didn't completely drain the engine when you replaced everything. It may be just a bad thermostat.
 

Italianwagon

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Thanks for the reply’s. Ya the temp gauge is moving allot more. Ok probably allot more efficient been awhile since a service
 

84 M1008

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It shouldn't fluctuate like that. It will maintain the temperature the thermostat is rated for. It should be unnoticeable unless you are heavily loading the engine.
 

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try a bleed procedure, i wouldnt think with air the engine wouldnt overheat, but ive never had air left over after a coolant service either. With the truck cold, rad cap off, start the engine. let it warm up. you could use a infared thermometer if you wanted. once your thermostat opens up, you should loose a small volume in the radiator from air escaping. Having your truck on an incline, so the rad cap is the high point of the system, and squeezing the rad hoses can help encourage air to escape.

of course, make sure to keep radiator full and make sure overflow tank has coolant
 

AuroraGirl

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Not related, but my 1996 F150 has a coolant gauge that about 1/3 of the entire sweep area is actually about 15 degrees of temperature change. Its actually really ******* annoying and I hate ford for it. I confirmed it with my obd2 live data. The coolant from about 190 to 205 sweeps about 1/3 the gauge face, in the center, and it makes me think the truck runs cold and hot all the time. Like, when your gauge is at 2/3 you instinctually think, oh, this is hot. But hookup scanner, its reading 198 degrees F.

Moral of the story, gauges can be misleading. I know squares have at least 2 different common readings
 

CorvairGeek

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Cheap thermostats can cycle like crazy too. I only buy OEM or 'high accuracy' units now.
 

SquareRoot

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Not related, but my 1996 F150 has a coolant gauge that about 1/3 of the entire sweep area is actually about 15 degrees of temperature change. Its actually really ******* annoying and I hate ford for it. I confirmed it with my obd2 live data. The coolant from about 190 to 205 sweeps about 1/3 the gauge face, in the center, and it makes me think the truck runs cold and hot all the time. Like, when your gauge is at 2/3 you instinctually think, oh, this is hot. But hookup scanner, its reading 198 degrees F.

Moral of the story, gauges can be misleading. I know squares have at least 2 different common readings

You used the F word. Cool
 

CorvairGeek

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Not related, but my 1996 F150 has a coolant gauge that about 1/3 of the entire sweep area is actually about 15 degrees of temperature change. Its actually really ******* annoying and I hate ford for it. I confirmed it with my obd2 live data. The coolant from about 190 to 205 sweeps about 1/3 the gauge face, in the center, and it makes me think the truck runs cold and hot all the time. Like, when your gauge is at 2/3 you instinctually think, oh, this is hot. But hookup scanner, its reading 198 degrees F.

Moral of the story, gauges can be misleading. I know squares have at least 2 different common readings
At least it reads something. Your oil pressure gauge of that vintage Ford has a resistor across the back, and it is tied to an warning light oil pressure switch (even says so in the shop manual). Took 2 tries for me with different older sending units to make the gauge imitate the mechanical gauge I was using when my F53 was new.
 

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