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This time, for the first time all these years, I drained both the radiator and block .. well, whatever came out when I removed the heater control valve.
I never have issues filling after a rad-only drain; I do it slow enough till it comes out the bleed screw and all is good.
But.. I wonder.. with the engine stone cold, won't it only fill to the closed thermostat, leaving the block empty?
When the engine runs, by the time the thermostat opens and I can fill more, won't the block overheat?
The Workshop Manual gives no special way of filling the block seperately.
Just thinking out loud, but if it's coming out of the bleed screw, wouldn't the block have to be filled?
I don't recall having any issues when I replaced my HG, always fill and bleed like you described, slow fill till it comes out the bleed screw. Some thermostats have a small hole to allow air and presumably coolant to pass and prevent the issue your talking about. I can't remember what the one in the turbo is like.
Just make sure when filling and bleeding that the front is slighting higher. Either via jacks or on a hill or slope. And make sure heater is full on to bleed air from heater core also. Bleeding will take a few tries without pressure tester equipment.
The arm is actuated by a cable, I think? I think these pics are from an early N/A, but as far as I know this part is the same. I would think you would be able to see the difference in state just by moving your slider on your dash.
I thought the heater valve was vacuum operated. That's what that little vacuum canister is for by the battery and the one way air check valve is suppose to help hold the vacuum which gets its vacuum source from the brake booster line. That's what that black and blue check valve is in your photo coming off the brake booster signal line.
Otherwise it takes forever to purge any air pockets within the system. And the 911 have coolant lines galore throughout the back to the front and in between.
Otherwise it takes forever to purge any air pockets within the system. And the 911 have coolant lines galore throughout the back to the front and in between.
I thought the heater valve was vacuum operated. That's what that little vacuum canister is for by the battery and the one way air check valve is suppose to help hold the vacuum which gets its vacuum source from the brake booster line. That's what that black and blue check valve is in your photo coming off the brake booster signal line.
Looks like you're right. Makes sense now based on the way it works (automatic climate control). New on top and old on the bottom.
Reading some more and was surprised to learn that these can fail spectacularly, not only dumping coolant in a hurry but potentially dumping it into the bell housing and onto your clutch and ruining it. Apparently there is an all metal Audi part that can be substituted.
03-14-2018, 10:58 AM
Filling coolant
