My car heater started acting up. It would heat, then no heat. So I put a new thermostat in, had the heater core flushed, and new coolant added. The other day after this, it got so hot it shut down. I had it towed, they changed oil, and put another thermostat in, but it is still doing same thing. Help, very low funding.

  • 4
    When you say, "it is still doing same thing" ... do you mean it is overheating and shutting down, or the heater will blow hot/cold? There appears to be multiple questions here, though they are related. Commented Jan 9, 2014 at 14:54
  • 1
    Did you checked that ventilator is working if hot? Is the water pump and its belt are healthy? Commented Jan 10, 2014 at 16:53
  • Did you check your vacuum lines, IDK about your specific vehicle, but on some cars the climate control is powered by vacuum and a vacuum leak will cause them to operate/fail intermittently based on engine load.
    – Jrican
    Commented Oct 16, 2015 at 5:10

1 Answer 1


Your initial approach was solid: New thermostat followed by a flush/fill.

....another simple thing you can try is replacing your radiator cap. Old radiator caps have seal erosion won't hold pressure, slowly leak coolant, and then once the coolant gets low, you'll get these symptoms--slow to heat and wild temp fluctuations.

So I think the only cheap thing left for you to try is replacing the radiator cap.

Also, you might check your coolant level a couple days (or even several hours) after you last top off the reservoir and run the engine. I've heard of radiators "burping", where it seems like they're full, then after the car runs for awhile, it's like "oh wait, but now it'll accept more coolant??" So this is just to be prudent make sure you're really starting with a full radiator.

If neither of those two tips gets you going, unfortunately this could mean a failing water pump. :/

  • Oh... as for @user1126070's question about your belt ..are you hearing any belt squeals, either on startup or when accelerating?
    – elrobis
    Commented Jul 22, 2014 at 18:34
  • @Катерина ..I was talking about the radiator and coolant system, not the engine oil. That should have been pretty obvious.
    – elrobis
    Commented Dec 15, 2015 at 15:36

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