Join the Car Talk Community!

Discussion Rules

Welcome to the Car Talk Community!

Want to ask a question or join the discussion? Great! Join now.

Sign In Register

Heater problems Toyota Rav4

Heater works when outside temp is 20 and up but is poor when it is colder. Replaced thermostat, flushed everything. Checked all the controls and such, looks good. after 30 min of driving this am still just warm heat, got out and felt upper and lower rad hoses, bottom was cold, top was warm but not hot, somethings not right. Temp guage shows about half within 10 min of driving but does not seem to be telling the truth. It will eventually warm up but takes a long time. Acts like there is no thermostat bu there is, it is new. The new one seems to work no differant than the old one. HELP<
Tagged:
«1345

Comments

  • edited January 2011
    Has the coolant system been checked for a head gasket leak which might cause air pockets in the coolant system?
  • edited January 2011
    Um, no. I would think i would have other issues if that were the case though? Water in oil, oil in water, poor running, something? The vehicle runs great, no oil burn, no smoke, gets 29 mpg at our elevation.
  • edited January 2011
    You either have a big pocket of air in the heater core or a partially plugged heater core.

    Raise the front of the car as much as you can. Use a hill,ramps or jack to get the radiator cap as the highest point. Take off the radiator cap (cold) and squeeze or fles the heater hose and radiator hoses to get the air out, Refill w 50/50 mix.
  • edited January 2011
    Thats a can do, a little more info for your pleasure. If i run the car, no rad cap, i can pull the heater core lines off and there is a trickle flow in or out. I flushed core several times on several occasions because everbody says core is the problem. flow through the core is not the issue but air may be. The cores on these vehicles are somewhat higher than the rad
  • edited January 2011
    Oh, thanks for your help, i feel i am a pretty decent mechanic but this ones is killing me.
  • edited January 2011
    Have you considered blocking part of the radiator with cardboard to see if that helps with the heat?

    BC.
  • edited January 2011
    I did that this morning, the cardboard was about 8x18, i put it in from of the top hose.
  • edited January 2011
    Did not seem to make any difference.
  • edited January 2011
    Perhaps you need a new water pump? This doesn't make any sense b/c you should overheat eventually if the pump isn't working. But if you have the car running and pull the inlet hose to the heater core you should get more than a trickle - unless I read that wrong. You're lower radiator hose should not stay cold either.
  • edited January 2011
    I am with you on this one, if the pump was weak, you would think i would have the opposite issue. That and pump with steel fins dont usually go bad, they start leaking. I think maybe i may have air in the core that will not come out, therefore little flow. but i dont know, i am at a loss. I just parked it on a hill to get the core lower than the rad, maybe i can push the air out.
This discussion has been closed.