Edmunds Answers



  • MrShift@Edmunds 04/28/09 6:36 pm PST

    I'd say you are either low on coolant level or your thermostat isn't opening fully. Some people might suggest erosion of the water pump impeller, but that's a rare fault and would be my very last guess.

  • paddy5 04/28/09 11:23 pm PST

    The coolant is right full. If the thermostat were sticking I would think the condition would be somewhat erratic - this happens each and every time consistently - also the hot air commences within a few seconds of speeding up the engine - and cold air starts after a few seconds of idling . As for the water pump impeller being worn - wouldn't that affect the engine coolant temperature so the engine would overheat?

    My gut feeling is that it is some kind of computer control problem with the heater. Anybody else out there have this problem? I've read of some horror stories on the internet re the climate control and radio/cd control failures (I think they are run off the same computer card) but nothing exactly like the problem I have.

  • MrShift@Edmunds 04/29/09 12:34 am PST

    I'm not buying that just yet, as that would require some kind of voltage rise and drop to adversely affect the module controlling the heat, right? And a vacuum leak doesn't explain it, because as you race an engine, the vacuum drops further--it doesn't get better (if the heater valve were vacuum actuated I mean).

    Okay, how about the coolant being air-bound? Have you added coolant lately?

  • paddy5 04/29/09 2:35 am PST

    I did add some coolant last fall - not sure whether this was before or after we noticed the heater problem. Are you suggesting it could be an air lock in the heater coil or somewhere in the heater system? If it is, how do you fix this?

  • MrShift@Edmunds 04/29/09 10:21 am PST

    Yes an air lock. Each manufacturer has their own procedure for filling---the BASIC strategy is to open the air relief valve on the heater hose and fill the coolant through the open radiator cap until it overflows through the plug. Then you button it up, install the radiator cap and warm up the engine. Then race it a couple of times, shut it down and let the engine cool (not cold, just around 120 degrees or so). Then refill your reservoir tank (don't open the rad cap). Repeat this a couple of times until the coolant level no longer drops in the reserve tank. If you hear any kind of gurgling or noise in the area of your heater box, you still have air in the system.

    When you pour coolant in the radiator (we are talking about the radiator, not the reservoir) you have to pour about 2 quarts a minute, no faster.

    so the general idea is a) fill up your coolant into the radiator until the overfill plug spills out, then b) button up and with repeated fillings through the RESERVOIR tank, keep doing it until the coolant no longer drops between cool downs.

  • paddy5 04/29/09 11:47 am PST

    I think I may get the dealer to change out the engine coolant. One note though - I haven't noticed any gurgling noise in the heater.

  • MrShift@Edmunds 04/29/09 11:55 am PST

    That may or may not happen in an air lock. If the coolant hasn't been flushed in two or more years, it's a good thing to do in any event.


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