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Cooling system questions

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  • Cooling system questions

    Doing thermostat and hose replacement and I have a few questions while i'm in there.

    1. Do you have to take the airbox and horns off to get to the heater to block and return lines? seems pretty difficult otherwise

    2. About a year ago I got a recall notice from BMW to bring it in for a heater bypass valve if the pressure got to high, supposedly it would rupture inside car at the blower motor, the supposed weak point. I was wondering if anyone else got this notice, As I now have to hack up the block to heater core hose because of this valve the dealer installed, was wondering if it was worth keeping or chucking.

    3. What are the 2 sensor plugs on the thermostat? temperature and something else? Since I have them off, are they 2 parts that should be replaced with the thermostat? or should they be only replaced when they go bad? how much do they cost? might just be best to replace them now since it's the original thermo and sensors.

    4. Anyone got a part number for the plastic tube that goes from the top of the radiator to the coolant expansion tank? seems 14 years of service and "gentle persuasion" was to much for it, and it snapped in half trying to get the hose off .

    The Chuck giveth, and the Chuck taketh away

  • #2
    I managed it somehow without. Since I could not get the plenum off around the horns (brake stuff blocks it), I would have had to take the whole deal off and my acorn nuts were not agreeing. I also replaced the water pump and had to take the alternator off, to get behind there to the small hose.

    I hacked the recall stuff off. I have a samco one in there now which is a single hose, but I have some rubbing issues with the plenum. Either my engine mounts are worn, or something else is up, so I put a piece of the old hose around the new one to stop the chafing. Becareful with leaking anywhere around the firewall/heatercore (check leakage in the footwell near gas pedal). Its hard to tighten the hoses in the back with the wiring harness in the way.
    You should be okay with a decent heater core. It was for the owners that would prematurely wear it out by flogging on the engine without it warmed up I believe.

    Umm, thermostat, temp switch...trying to think...