anth115

Hi all. I have a 2006 Z06 with 55,000km/35,000 miles and recently refreshed all fluids before winter storage. However I suspect I have air trapped in my cooling system, specifically in the heater core.

I want to know:

1. If anyone has any tips for how to correct this (aside from draining it all and doing a vacuum fill). See what I’ve already tried below (happy to try again though).
2. How dangerous you think it is to drive like this. The coolant temp on the gauge and display read 100% normal, but of course I don’t want the risk of creating a hot spot/failure point in the block.

Why I think it’s the heater core/symptoms:

• The heater is generally weaker than before. Setting the HVAC to 24°C/75°F used to give good, strong heat even on the lowest fan setting. Now, it often blows ambient temp or just slightly warmer than ambient.
• If the car is restarted when already warm, the heater will work well for a few minutes and then weaken as described above. I think this is when the air gets pushed up into the heater core creating this condition.
• If I set the thermostat to max heat, it still gets very hot. This issue is only visible when you set it to a midrange temp (in comparison to what that delivered before my coolant drain & fill. Nothing unusual with different vent modes or from left to right.

What I’ve tried:

• running with idle/light throttle until thermostat opens with front end raised, car on ground, front left raised.
• Squeezing either rad hose once the thermostat is open
• Drain and fill procedure from the service manual.
• With the car off, pulling the steam vent hose Off the driver’s side head and blowing into it. Coolant quickly came out of the vent hole with no bubbles. I did not try this with the car running as it’s right above the (newly replaced) belts and I’m worried about spilling.
• Driving at high RPM up steep hills, spirited driving, normal driving (about 1/4 tank of gas’ worth).

Just in case it matters: I refilled the car with 60% distilled water and 40% pure AC Delco Dexcool. The expansion tank is filled to the correct level, and this no longer seems to move once the car has cooled down (already topped off).

Thanks in advance for any input.

Anthony

AzMotorhead

I've never looked at the serv manuals instruction for draining and re filling. doe s it say to use a vacuum fill system?
Did you change your thermostat? and is it stock temp ?
Try to find a shop with a "Airlift" tool. you dont need to drain and refill with that just put a vacuum on the system to draw the air out.

drewz06

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worth it....