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Discussion Starter #1
95 SS 45k miles
Antifreeze coming out of overflow tank. Not running hot. Did a coolant flush 2 months ago.

Anyone know the cause and fix?


95 Chevy Impala "Stacy"
 

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Filled to the "cold" mark on the tank - or overfilled?
 

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It's not an overflow tank. It is a coolant reservoir that is part of the pressurized cooling system. A overflow tank is something entirely different. Start by replacing the pressure cap. Either a 15lb 94-5 or 16 lb 96 will work.
 

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Discussion Starter #5
Someone was telling me to also bleed the air out of the system. Anyone have instructions on that?


95 Chevy Impala "Stacy"
 

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It's not an overflow tank. It is a coolant reservoir that is part of the pressurized cooling system. A overflow tank is something entirely different. Start by replacing the pressure cap. Either a 15lb 94-5 or 16 lb 96 will work.
Actually, I believe the 96 uses a 18 lb Pressure cap and not 16 lb. There are a few threads that discuss the differences. But it appears the OP has a 95 in this case and should be a 15 lb cap with the Green dot. The 18 lb caps have a Orange dot which I believe indicates Dex-cool usage in a 96.

Someone was telling me to also bleed the air out of the system. Anyone have instructions on that?


95 Chevy Impala "Stacy"
I doubt that is the issue and most likely a leaking cap. The rubber washer inside the cap can leak. A good idea to replace the cap anyway if its got some miles on it....cheap insurance.

Still based on your question you certainly need to "bleed" the system correctly. Just do a search as there is already lots of info here on how to do this if you just search for it. Typically the engine will overheat if not bled and you may also experience what is referred to as a "waterfall" sound which some have likened to boiling.
 

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bleeding cooling system
Considering CRSSDMS's wise advice, I've made some important corrections to:
The 94 B-Car Field Service Manual's Draining & Refilling Procedure:

DRAIN
0. Shut off the engine, dumbass.

1. If car is hot, loosen coolant recovery reservoir cap VERY SLOWLY until a slight hiss is heard. When hissing stops, continue loosening cap VERY SLOWLY until a slight hiss is heard again. Repeat until cap is removed.
[Could take up to 15min.]

2. If car is cold, just remove the coolant recovery reservoir cap already.

3. Loosen and eventually disconnect the radiator outlet hose at the bottom of the passenger-side of the radiator.

4. Do something to protect the Opti-Spark from the coolant about to issue forth from the air bleeder valve.

5. Open bleeder.

6. Remove both knock sensors on both side of the engine block.

7. Allow system to drain completely.

REFILL
8. Re-tighten radiator outlet hose.

9. Install knock sensors.

10. SLOWLY fill cooling system through the coolant recovery reservoir, just past the top of the 'FULL COLD' mark. [The slower you pour, the less air you will need to bleed later.]

11. Close bleeder when bubbles disappear, and only coolant is visible.

12. Run engine till thermostat opens.

13. Reopen bleeder.

14. See Step #11.

15. Reinstall coolant recovery reservoir cap.

[16. Experience has shown that steps #11 thru #15 may bear repeating, depending on how thoroughly the system was bled, and how fast coolant was poured in.]

Haven't gotten around to getting one, but the
Enhanced Bleeder Valve
is pretty sweet, and very highly recommended.
 
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