Thermostat is cooler = better (1 Viewer)

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Hey guys, hope you're doing well with how crazy its been around lately.

I have a question about thermostats but first a little background.


Skip if in a hurry!!!
I have a 1fz powered 100 series Land cruiser that when I first got had a little overheating issue wasn't really a big deal but at the time I didn't have enough time to fix the issue. So basically the car used to over heat just a little bit enough to get the ac to shut off as soon as I stop and it will return to normal within a minute of driving so to stall the issue I changed the thermostat from the regular 180f unit to a 170f thermostat from a 1hz I think it was that kept everything ok for a while until I had the time to overhaul the cooling system on the car so a fan clutch, radiator and coolant flush later (wp is still doing fine) the temp on the gauge dropped to what I think is way too low I will attach a pic but it sits at about half way of where it would normally sit this is as high as it gets while cruising at speed no matter how hot the ambient temp is however, while parked the temp will start to creep up mostly to where it should sit and on rare occasions a little high to where the ac will cut off.

Question:
Is this related to the thermostat staying wide open for most of the time.
Also the car is desmogged (it comes from factory with no egr or oxygen sensors) so is it fine to keep it as is or should I replace the thermostat with a 180f one.

If I had to change it I know there is a gasket that goes around the thermostat is there also a second gasket for the housing or do I use some sort of sealant around it?

Sorry for all these questions but this topic is way too confusing for me as where I live many people think cooler= better but I have a bad feeling about this assumption

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Is this related to the thermostat staying wide open for most of the time.

possibly, but you should verify your engine temp another way. the gauge is just there as an indicater and accurate enough to indicate a problem but not really a specific temp.

If I had to change it I know there is a gasket that goes around the thermostat is there also a second gasket for the housing or do I use some sort of sealant around it?

no, just the t-stat o-ring
 
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the main issue with 'too cool' is the ECU may think the motor is not up to operating temp and enrich the fuel mixture

the big issue here is excess fuel consumption / foul the spark plugs and more importantly potentially glazed / washed bores. If an auto, the OD may also not kick in as its dependant on a minimum coolant temp as well.

My Wifes 2006 Mazda 6 had a similar issue in that the thermostat would not fully close and the car ran cooler plus not much heat from the heater in winter. Replaced the thermostat, heater worked great and fuel consumption reduced noticeably and temp gauge back to the normal half way mark.
I did remove & clean the spark plugs and they were obviously running rich

fix the thermostat
 
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LInk to buying a modified fan clutch (if it's the correct part number):


Link to a very long thread with a ton of information about modifying fan clutches:


Can you post up the part number of the stock fan clutch in your 100 series?
 
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أَهْلًا وَسَهْلًا

"So basically the car used to overheat just a little bit enough to get the AC to shut off " no sir its not little bit it is gigantic over heat
 
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LInk to buying a modified fan clutch (if it's the correct part number):


Link to a very long thread with a ton of information about modifying fan clutches:


Can you post up the part number of the stock fan clutch in your 100 series?
Sure part number is: 1621066020 it is a blue hub clutch
 
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أَهْلًا وَسَهْلًا

"So basically the car used to overheat just a little bit enough to get the AC to shut off " no sir its not little bit it is gigantic over heat
Probably the old radiator was pretty much gummed up from inside and the old fan clutch did not engage however the issue is now solved and I think the car is probably cooling the engine way more than it should
 
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Probably the old radiator was pretty much gummed up from inside and the old fan clutch did not engage however the issue is now solved and I think the car is probably cooling the engine way more than it should
If the radiator has been replaced or cleaned AND the fan clutch has been improved, then install the correct thermostat.

The thermostat fully opens at the "optimum" operating temperature. It is designed so the engine does not run too cold. The fan clutch and radiator are supposed to work in unison to keep the temperature from exceeding the limits of 226°F at AC cutoff.

If it is idling and the temp climbs, then the radiator and/or the fan clutch are NOT operating properly.
 
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If the radiator has been replaced or cleaned AND the fan clutch has been improved, then install the correct thermostat.

The thermostat fully opens at the "optimum" operating temperature. It is designed so the engine does not run too cold. The fan clutch and radiator are supposed to work in unison to keep the temperature from exceeding the limits of 226°F at AC cutoff.

If it is idling and the temp climbs, then the radiator and/or the fan clutch are NOT operating properly.
Both replaced with new units the overheating issue is pretty much non existent it will only overheat if the ambient tempreture is above 110f and only if it idled way too long (30 mintues and above) and it will only go up enough for the ac to cutoff and as soon as that happens it will drop quickly. Everything is in good working order and engine was overhauled not too long ago so I know the head gasket is still fine what I think is happening is that the thermostat opens way too soon not giving the coolant enough time in the radiator to shed heat I will try to replace the thermostat to a correct one (180f) this weekend and will keep the truck idling for an hour or so to see if anything happens and report back
 
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Got some time on my hand today so I went and got an oem thermostat waiting for the car to cool down a little more so I can have a crack at it hopefully all goes well
 
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I think I found the problem. The dofus who installed the previous thermostat had it upside down with the jiggle valve at the 6 o'clock position so it was most likely full of air! No wonder why whenever I opened the hood the radiator flooded everything with coolant
 
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If it is idling and the temp climbs, then the radiator and/or the fan clutch are NOT operating properly.

@BILT4ME we both live in the same neighborhood it is hot very hot too hot hotttt

Toyota installed an electric fan for the hot climate in front and I added a second SPAL

And you need to vent hot air from the engine bay like raising the back of the hood with spacers or openings in the hood

My wifes 4X4 has no problem with the hot claimet

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hot.jpg
 
Joined
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@BILT4ME we both live in the same neighborhood it is hot very hot too hot hotttt

Toyota installed an electric fan for the hot climate in front and I added a second SPAL

And you need to vent hot air from the engine bay like raising the back of the hood with spacers or openings in the hood

My wifes 4X4 has no problem with the hot claimet

View attachment 2485050View attachment 2485051View attachment 2485056
Yeah everyone complains about winter and yet I've never seen it go below 16° where I live at least up in Israel it gets a little colder than that I think as for other fans I may do that in the future but for now I'm still slowly baselining this old girl to be a DD and a long distance traveler owned it since new never beat on it of road except for maybe once or twice in its whole life!
 
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"I've never seen it go below 16°...

At -60C your tires will have a flat spot in them for a mile or two... other than that it's fine!
 

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