warming up issue

[chris00326]

So after letting my car warm up and then drive it about a half mile it goes cold again. So I replaced the thermostat with a 160 degree failsafe thermo and flushed the system. Same issue. I replaced coolant temp sensor. Same issue. My next step I guess is the sending unit. Just wandering if I might be missing something? Has anyone else had this problem? I don't think it has to do with the fan switch cus they turn on and off...

 

[Blu92]

I'd check the sending unit. Once the car warms up and the gauge drops turn off the car, unplug the wire from the sender and ground it to a good ground. Then turn the key on and see if the gauge reads hot. If so the sender is bad. If not check the circuit or the gauge. Of course check fuses that are involved with the circuit too.

 

[74runner]

You said it "goes cold again" do you mean the heater blowing in your car?
If you do you might have an air lock.

Pull the rad cap, top up the fluid and start the car with the heater on full blast and let the car run at 2000rpm until the rad burps out all the air, be careful when the rad fans come on because your T-stat opens and you might get a hot coolant shower!
When the air is all out the coolant should stop bubbling and trying to overflow, if is doesn't stop at all you might have a blown head gasket.
You will need to keep topping up the coolant level until your done.

 

[bud09]

i have the same problem. my temp gauge will slowly drop as i'm driving but it doesn't drop all the way. i should take a video tomorrow when i go out.

 

[rough]

Any update on this? I have replaced my thermostat 3 times, "failsafe" and still having this issue. It sucks being cold!

You said it "goes cold again" do you mean the heater blowing in your car?
If you do you might have an air lock.

Pull the rad cap, top up the fluid and start the car with the heater on full blast and let the car run at 2000rpm until the rad burps out all the air, be careful when the rad fans come on because your T-stat opens and you might get a hot coolant shower!
When the air is all out the coolant should stop bubbling and trying to overflow, if is doesn't stop at all you might have a blown head gasket.
You will need to keep topping up the coolant level until your done.

With an airlock, you would hear the system gurgle the fluid, or rush forward once it's pushed.

I think it's something with these fail safe thermo's , I'm going out today and replacing mine with a non failsafe "I've used 3 of them so far in the past 2 months" and see what happens.
I do notice it takes a lot longer for the vehicle to warm up sitting at idle, so i'm assuming the thermostat is junk, as sometimes I can be doing 70 and it's 200 then other times it's cold.