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bleeding cooling system

44K views 27 replies 16 participants last post by  coltonx3 
#1 ·
what is the proper way to bleed a cooling system?
 
#2 ·
I don't know about "proper" but here is my method. With the cooling system cold and full I open the bleeder screw and let gravity work to remove some air. Top off the system if needed, seal it up and crank engine. While waiting on it to heat up I jack up the front of car and put on stands. If you are impatient stick a dime in the throttle stop to hold the rev's up. When it's up to normal operating temps I turn off engine and open the bleeder to purge more air. A lot will come out now. Let the car cool, top off coolant level. Repeat. A third run of this never gets anymore air out for me. But it's nice to do just to be certain.
 
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#18 ·
Here's my take on the 94 B-Car Field Service Manual's Draining & Refilling Procedure:

3. Open the coolant drain valve/petcock at the bottom of the driver-side radiator end tank.
OR
Loosen and eventually disconnect the radiator outlet hose at the bottom of the passenger-side of the radiator.
One thing I would like to add here is when you drain the old coolant prior to a flush do NOT repeat do NOT looSSen the plastic petcock as they are known to like to break on the first loosen and never seal properly ever again.

Just do the lower rad hose method.
 
#5 ·
Are the LT1 Corvettes & Camaros any different in the same years? The reason I ask is because when you do a search on bleeding an LT1 cooling system it appears all they do is open the reservoir cap, start the motor, let it warm to operating temp, check to make sure their are no air bubbles in reservoir, top off if needed. The reason I ask is because I'll be replacing an upper hose soon. Thanks!!
 
#19 ·
Considering CRSSDMS's wise advice, I've made some important corrections to:
The 94 B-Car Field Service Manual's Draining & Refilling Procedure:

DRAIN
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.

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

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.

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.]

Haven't gotten around to getting one, but the
Enhanced Bleeder Valve
is pretty sweet.
 
#21 ·
You're probably OK,engine will overheat pretty quickly if you didn't.
 
#22 ·
engine must be "on" at idle to bleed the cooling system.

if using some form of "quick bleed" valve with a hose, just run the hose back into the resovoir until bubbles stop coming out. close valve, remove hose, replace resovoir cap, no mess.

also it is helpfull to have the nose of the car slightly elevated when bleeding.
 
#23 ·
Just changed thermostat and lower radiator hose. Bled it for two good rounds as listed and got a lot of air out from what it seems. Was just finishing the last round and no air came out for a few minutes so i closed the bleeder, topped off the fluid level and capped the tank. I should be fine right? Reason i ask is i get paranoid adding more fluid without bleeding again.
 
#24 ·
I don't get how these people bleed the system with the cap off. With no pressue in the system you are not going to push any air bubbles up to the high point in the system, which is where the bleeder is. I let it run all sealed up until pressure build's in the hoses, then open the bleeder. I do this 2-3 times. 3rd time I squeeze the lower hose while I open the bleeder one more time, let it cool off, fill the tank to the top of the divider down in there, and cap it up. Couple days of short runs and I check it, usually have to add about 1/2 a quart or so, that's it.
 
#25 ·
Actually,the coolant level in the reservoir is the highest point. All fluids tend to seek their own level,this is why many (including myself) do it this way. Occasionally, I'll crack it loose when under pressure for my own amusement.
 
#26 ·
Not to contradict anyone's advise on here but I have used the Lisle funnel kit #24610 when ever I refill the coolant system on my bbodies and wbodies. Once drained completely, I crack open the bleeders and hook up the funnel, start filling the system, you will hear hissing coming from the bleeder valves, continue filling until coolant starts coming out of the bleeders, stop and close the bleeders, fill the funnel a little less than half and start the engine until it warms up and tstat opens, once opened you will start to see the coolant get sucked up by the engine, put the plug in and remove the funnel, seal the tank. I usually do this and don't have to continue to bleed.

*NOTE: TRY AT YOUR OWN RISK.

http://www.walmart.com/ip/Lisle-Spill-Free-Funnel-Thrd/19654863
 
#27 ·
Few ways to skin this cat...I bought Norm's "Freesbleeder" back when he was selling for $17. There are other valves people have come up with to "quick bleed".

mess free. I just warm up car and then open valve with wrench and coolant flows right into resevoir. when air bubbles stop just close valve, pull tube, replace cap. Done
 

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#28 ·
I say this oncs again its a long story but I changed the t stat and I completly draind the block filled it back up drove for about 5 min then woke up in the morning toped it off to right level and been driving all day in like 100 deg heat and no problems I never bledd the system funny how people stand by bleeding it just my .02
 
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