Did you put the thermostat in backwards? If you did, it wont open when hot. Thermostats look pretty much the same - with some minor variations. It's important to note the the side with the spring should be facing the (hot) engine and the other side facing the (cool) radiator as shown in the image below. If the spring side doesn't get hot - it won't open to let hot water from the engine flow to the radiator for proper cooling.
Testimonial: "Thanks,but no its not upside down...flushed radiator.and replaced water pump..any thoughts"
-How high in side temperature gauge...? If the gauge is between
normal then you're okay.
-Why Bottom hose is cold...? Because the thermostat is still closed.
-In order for the thermostat to open. (the temperature at the thermostat area must reach what ever the thermostat set for.
Any questions...?
Good luck
mai
SOURCE: seized thermostat
Not always. If you have a KA24E (2.4L 4 cyl) engine, the thermostat is located where the lower hose connects to the engine. I have had to change mine. It's easiest to get to if you remove the power steering pump and set it to the side. The thermostat housing is directly below where the PS pump mounts.
SOURCE: bottom radiator hose cold. upper radiator bulging.
The fan won't come on because the thermoswitch is in the bottom of the radiator, without coolant flow the switch never gets hot. Just because a part is new doesn't mean it is good, is the thermostat an aftermarket part ? I would take out the thermostat (leave the gasket) and see if the bottom hose gets warm. If the bottom hose does not get warm, you may have a blockage or bad water pump
SOURCE: 2002 dodge 1500 Changed radiator, thermostat, and hoses. No heat
Why was radiator replaced?Did it have heat before ? If it was plugged, the heater core may also be plugged. Try flushing it with a water hose in both directions. I dont know why the botton radiator hose would be cold, the radiator should be a uniform temp and the air coming through the radiator should be HOT, when the engine is at operating temp. What condition was the old coolant? if it was rusty, the water pump may have lower flow than normal.
SOURCE: 1991 honda accord is overheating. Installed new
When the car is completely cool,check the electric fan(s) for smooth rotation.
Clean/check/change the thermo sensor,contact and wire.
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Excavate air pocket in coolant system / check for head gasket leak
This test will kill two birds with one stone.
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MAKE SURE THE COOLANT SYSTEM and ENGINE IS COLD!
RAN THIS TEST IN A WELL VENTILATED AREA ONLY!
You will spill some coolant during this air pocket purge test.......BE
KIND TO THE ENVIRONMENT and ANIMAL please clean up after the test!
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Put the front end on a pair of ramp or park your car on a VERY STEEP HILL (radiator facing top of the hill) .
Top of the coolant reserve tank
Let it ran for 10-15 minutes.
Monitor for air pockets escaping from coolant reserve tank.
Small amount of bubbles is OK at 1-5 minute mark
After the thermostat open up (after 195 F warm up) at
5-12 minute mark or after high idle you should see less bubbles.
If you do not see any in rush of bubbles then your thermostat may be
partially stuck or rusted badly inside the thermostat hosing.
Give the thermostat host few gentle taps.
If you see larger bubbles surfacing after 15 minutes then should do a
hydrocarbon (HC) dye test to test for potential head gasket leak.
Let engine cold down and top off coolant reserve tank.
Start monitor for coolant lost
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A coolant flush is require every 2 years or 24,000 miles.
I recommend the thermostat that has a relief pop-let to reduce the change of burst radiator and coolant hoses.
Make sure you get a new thermostat gasket,black RTV and fresh coolant for the job.
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