I replaced the radiator and thermostat on my 98 Subaru Forester but still when I drive it the temperature gauge reads over the hot line the heater doesn't work but the coolant doesn't seem to be circulating to where its supposed to be. It spills back into the reservoir tank (plastic tank attached to the radiator) then it spills out onto the engine and everywhere else.

I don't think it's the head gasket cause the engine runs fine and it doesn't over heat at all plus it still hauls ass. Just this coolant problem. The only thing I can think of is the temperature sensor or heating coil. I just bought it and I can't drive it because I'm afraid to make it worse.

  • Have you bled the cooling system properly? Some cars need to have the front or back raised to help with this.
    – Solar Mike
    Commented Mar 10, 2018 at 10:11
  • I'm pretty sure. I replaced all the hoses drained all I could out of it. I am pretty new at working on cars. But dad was a mechanic he helped he's stumped too. Then I remembered when I bought the car the girl said I need to replace the sensor. She was driving it for 9 months with the temperature gauge reading over the hot line and it never over heated.
    – Trevor T
    Commented Mar 10, 2018 at 10:16
  • did you change the radiator cap?
    – user36524
    Commented Mar 28, 2018 at 18:35
  • You mentioned that your father was a mechanic. Are you set up to do a Vaccume Test? A Leak-Down Test? A Dry and Wet Compression Test?
    – NitrusInc
    Commented Mar 28, 2018 at 19:32
  • When you replaced the radiator, did you reuse the factory-style Constant-Tension clamps or did you use worm-style hose-clamps?
    – NitrusInc
    Commented Mar 28, 2018 at 21:38

3 Answers 3


I would start by verifying your water pump is operating. You could clamp a piece of clear hose in-line on one of the pipes and most likely verify this.

Attempt Grounding out your temperature sensor and verify if your gauge is working correctly, after doing this use an ohm-meter / Digital Multimeter and check the resistance of your sensor. the following would be normal findings based on temperature

Temp in °F Resistance (ohms)

212 ----------176

194 ----------240

176 ----------332

158 ----------458

140 ----------668

112 ----------972

122 ----------1182

104 ----------1458

95 -----------1800

86 -----------2238

76 -----------2795

68 -----------3520

58 -----------4450

50 -----------5670

40 -----------7280

32 -----------9420

if your findings are grossly out of line consider replacing the part; at $20-$30 it wouldn't be a bad rule-out anyway.

The water pump would answer the lack of heat however the sensor would not; on the passenger side of your vehicle under the hood there should be 2 hoses that reach go to/thru the firewall; with the vehicle running for approximately 5 minutes feel both hoses: if one of the hoses is warm/hot and the other is cold then you have a failed heater core $20-$35 for your vehicle will buy the replacement part. if both hoses are hot/warm then you have a failed temperature switch inside the vehicle (vehicle to vehicle this can be time consuming and vary in price); if both hoses are cold you have again verified your water pump has failed and should be replaced immediately.

Another consideration is verifying that all hoses from your previous repair remain uncrimped or folded.

I hope this information helps you; if it does please remember to mark it as the best answer.


The first thing that comes to my mind, is that the water pump is not working. If the water isn’t circulating, the water in the engine will boil and cause the loss of water that you are experiencing.

Because the water isn’t circulating, the heater will also not receive hot water, so it will blow cold.

  • Ok. That was the other option. That really helps a lot thank you. I'm just really hoping its not the head gasket.
    – Trevor T
    Commented Mar 10, 2018 at 10:32
  • 1
    @TrevorT Wouldn’t you be better waiting for some other suggestions before marking this as the best answer?
    – HandyHowie
    Commented Mar 10, 2018 at 12:21
  • I didn't even know that's what that meant. Oops. First time on here.
    – Trevor T
    Commented Mar 10, 2018 at 16:44
  • @HandyHowie With modesty, and honesty like that, you deserve ALL the points. Good on you, man! Glad to see some good peoples on here.
    – NitrusInc
    Commented Mar 28, 2018 at 19:29

I had the same issue. The 2 little hoses on top of the rad are the cause. Switch them around, you have them in the wrong spots lol

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