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Category: Chevy
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Experience:  General Motors Engine Performance and Diagnostic Certified
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2010 Impala: air in the cooling system I just cannot seem to bleed

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I have a 2010 Impala and have air in the cooling system I just cannot seem to bleed out - tried hot and cold. Noticed the heating inside goes cold too when at idle, ok when moving along. Installed a flushing tee to assist in bleeding air out. Just can't seem to get the gurgling to stop in the heater core. Seems to go away once hot or up to highway spped. Any hints or TSBs on this or procedure that for sure will work? Impala has the 3.5 L engine.

ASE Master Guru :

Hello, my name isXXXXX is the fill procedure from G.M.

Filling Procedure

    Caution: The procedure below must be followed. Improper coolant level could result in a low or high coolant level condition, causing engine damage.

    Caution: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  1. Close the radiator drain cock.

  2. If a complete engine block drain was required, install the coolant drain plugs to the engine block. Refer to Draining Fluids and Oil Filter Removal.


  4. Remove the vent cap from the top right side of the radiator.

  5. Note: Use a 50/50 mixture of DEX-COOL antifreeze and clean, drinkable water.

  6. Slowly fill the cooling system with a 50/50 coolant mixture until the coolant comes out of the radiator vent. Refer to Approximate Fluid Capacities.

  7. Install the vent cap to the top right side of the radiator.

  8. Slowly fill the cooling system with a 50/50 coolant mixture until the coolant level is visible and stable at the fill neck.

  9. Install the pressure cap loosely, threaded on about one turn.

  10. Start the engine and raise the engine speed to 2500 RPM and hold it there for 40 seconds, then shut engine off.

  11. Remove the pressure cap and fill the coolant system until the level is visible and stable.

  12. Install the pressure cap loosely, threaded on about one turn.

  13. Start the engine and raise the engine speed to 2500 RPM and hold it there for 30 seconds, then shut engine off.

  14. Remove the pressure cap and radiator vent cap, fill the coolant system until the coolant comes out of the radiator vent.

  15. Install the radiator vent cap.

  16. Install the pressure cap loosely, threaded on about one turn.

  17. Start the engine and raise the engine speed to 2500 RPM and hold it there for 20 seconds, then shut engine off.

  18. Remove the pressure cap and fill the coolant system until the level is visible and stable.

  19. Install the pressure cap, fully threaded on.

  20. Fill the coolant recovery bottle to the indicator line, then add 400 milliliters (13.5 ounces) more.

  21. Start the engine and run it above 2500 RPM until it is hot enough to open the thermostat, this will allow the trapped air to be purged from the engine.

  22. Complete a series of three, 4 second-duration idles with 4 second-duration 3000 RPM cycles.

  23. Turn the engine off and allow it to cool down to room temperature.

  24. Fill the coolant recovery bottle to the indicator line.

  25. Inspect the concentration of the engine coolant using the J 26568 Coolant and Battery Tester .

  26. Rinse away any excess coolant from the engine and the engine compartment.

ASE Master Guru :

Thank you for using Just Answer and please remember to click "accept" before leaving.


Hmmm - ok . You there?

ASE Master Guru :



Ok - didn't know this rad had a vent cap - had a 2004 Impala and it has over 400 000 km on it and always managed to get rid of gurgling - this 2010 is being a pain... any TSBS on that issue?

ASE Master Guru :

no known TSB just the published fill procedure for this car


I noticed that the rad overflow tank never seems to get lower after the engine cools. I also noticed that when the car is idling, it gets coller inside at the vents - is this all attributed to the air locks and gurgling?



ASE Master Guru :

Yes, the air in the system tends to get trapped in the heater core thus giving you the "gurgling" noise that you here and the reduced heat from vents. It will also cause your temperature gauge to fluctuate.


Temperature gauge seems to stay steady. Anyways - thanks for your help - one last question - this was a one shot deal - I didn't sign up for any monthly plan or charges , did I?

ASE Master Guru :

nope, you will only be charged when asking questions and then clicking "accept"


Thanks - lets hope it works!

ASE Master Guru :

Thank you for using Just Answer

ASE Master Guru and 4 other Chevy Specialists are ready to help you
Customer: replied 5 years ago.
Checked rad - no vent where diagram shows it on my model. Mine is a US Impala as well... brought it up from Buffalo....
o.k. If no vent present on your model then you will need to do a Vac-n-Fill procedure. This requires a special tool . Attached is the procedure.graphicgraphicgraphic
Customer: replied 5 years ago.
Where do I get such a tool? And if I have to buy, is it expensive? I cannot see images of tool in the attachments you provided... so not sure what it looks like either...
Most tool vendors carry them(snap-on,mac,cornwell,etc)I believe Napa stores also sell them. I am currently unable to upload image but will be happy to do so later this evening.
Here is a pic of what the tool looks like.
Customer: replied 5 years ago.

Thanks so much - I am going to try tonight to see if I can remedy the issues without buying the tool - if it still doesn't work I'll go to NAPA - we have them up here in Canada. Thanks again! Rick


no problem and good luck
Customer: replied 5 years ago.

Well, I tried the fill procedure - worked for about 1/2 hr but then when the engine was turned off, started to gurgle again when it cooled. unreal. Was NO swishing / gurgling after following the procedure... ran hot ok. Seems to suck air into the system somewhere when it cools. Overflow tank also doesn't go down... what do you think? Air getting into the system somewhere else? I see no leaks on the outside of the engine block (head gasket leak) and the exhaust isn't white (internal head gasket leak)... the rad fluid seems abit frothy and bubbly when I use the flushing tee to bleed off the air (not brown as would indicate a head gasket leak) but the fluid in the overflow tank doesn't appear off colour.... and I don't smell any inside the car (heater core leak)...


I dunno... guess I have to buy that vacuum tool... hate to spend money if I don't have to.. The overflow tank doesn't suck fluid back when it cools and it gets the air in again when it cools... seems to me that somehow air is getting into the system. What do you think (sorry for the multiple questions).



No problem on questions. In order to fully get ALL air purged from system you will need to use the vac tool. Perhaps a local shop would be willing to lend/rent you theirs so you don't need to purchase one. At this point I don't believe you have more air entering system, rather an air pocket that continues to remain trapped somewhere in the system. This is why GM has created the procedure I sent you requiring use of vac tool.
Customer: replied 5 years ago.

I know the 3.1 Ls (notoriously), the 3.4 Ls, and even the 3.8 Ls (lesser extent) had an intake manifold gasket leakage issue at one time... could THAT be a spot where air could be coming in, causing this constant gurgling to occur after it cools?


But I see no white exhaust that would indicate that...

On my old 3800 Impala engine, I also had one of two plastic elbows (which transfer rad fluid from the main block to the heater core outlets - they are located above the water pump) leak - THAT took me forever to find as the upper elbow had only a small crack and slowly dribbled it over the block where it would evaporate off. But I don't see such elbows on the 3.5L.


Anyways - could a leaking intake manifold gasket cause the bubbling to occur? I know the intake has been removed once on this engine...


OTHERWISE... guess I'll see if I can rent the vac tool or borrow it somewhere...



It is possible the intake is leaking but highly unlikely due the fact you see no evidence of it. Check oil and make sure it does not look like a milk shake. The 3.5 is more prone to have the cross over tube leak coolant externally versus anything else I've seen so far. I still feel that the first course of action should be to properly perform fill procedure before speculating on what could/might be a problem, especially with no physical evidence to back it up.
Customer: replied 5 years ago.
Ok - will probably try again tonight and stop by the local partsource (our equivalent of Pep Boys) to see if I can sign out the vacuum tool from them - if they have. Otherwise its off to the NAPA store.

I will check the crossover tube closely as well.

Will keep you posted! Thanks again for all the help!

no problem
Customer: replied 5 years ago.

Ah - I don't know what to do with the thing... went to a Partsource and they don't have the equipment to rent or buy. Haven't made it to the NAPA store yet but suspect they won't either. I can bleed the sir out till it makes no noise then its back again the next morning when it cooled down.


One thing I didn't mention before is that I have a propane package on the engine - the installers put the propane converter in-line originally with the heater core lines and the propane system kept shutting down cause it would get too cold. Then they switched it to be in-line with the bypass line at the front of the engine and the converter stays hot. But the gurgling continues.


I can only surmise that the system is sucking air somewhere either on the lines leading to the converter, or in the converter itself. I see no leaks though.


This is a PRINS propane system - vapour sequential injection - similar to multiport fuel injection. Not cheap - a $5000 add-on. I do alot of commuting so it pays off well. In fact it was in the 2004 Impala and it ran well from 166,000 km to the day I took it out just shy of 400,000 km. The 3.8 STILL runs smooth - almost better than the newer 3.5L.


Anyways - this has ticked me off a fair amount because it had no issues in the 3.8L, but does with the 3.5. Could the water pump simply be too weak to handle the additional piping and converter?


What do you think?



HMMM! propane? I can honestly say I have no experience with Propane fueled vehicles. From what you are telling me, it sounds feasible that the converter could be leaking, but with no physical evidence (white smoke, coolant staining, etc.) I am not sure. As far as the water pump being to weak to handle the extra capacity, doubtful. Unless the Propane components require vast amounts of coolant, the water pump should easily handle the extra capacity.
Customer: replied 5 years ago.

The installer believes the water pump should be able to handle it as well - unless it is weak / bad. Hard to say. This is not a full propane conversion but more like a hybrid . The propane system is actually a second fuel system which attaches to the car - so a separate fuel tank, separate computer, separate set of injectors and injection lines. It has a module which copies the timing from the OEM system and puts it to the propane injection system... I can change between propane and gasoline at will. The converter takes coolant from the system and uses it to turn liquid propane into gaseous - so its basically a heat exchanger. I have attached a few photos of the converter and the injectors (stock photos not of my system but exactly the same).


This is a view from the top of the converter;


These are the individual injectors...

It doesn't need a huge volume of rad flyuid from the OEM system...and the lines leading through the converter from the front of the engine (bypass line) are in series... it worked just fine on the 3.8 L engine.

Anyways - the installers figure it is just an anomoly with the 3.5 L engine. That, or a bad water pump. They will charge me $$$ to rip the intake apart to check the installer work.


My last ditch effort is to use a liquid stop leak and see if that stops the gurgling from coming back, once I bleed it. I know I know - heater core... I have used them before without any ill effects.


The only other thing I can think of is that the installers messed up the intake manifold gaskets and it is sucking air through there when it cools down. They did have to take the intake manifold off to install the individual injector lines.


Other than that... seems to run ok once it gets up and running down the road. If I leave it and don't purge it the gurgling just gets worse.


Its too bad you're not too far from the Canadian border - sau near Niagara Falls or Buffalo - I would drop by for you to look at the system up close.


Otherwise - keep posted. I'll let you know what I come up with .


TTYL then.



sounds good,be sure to give the Vac-n-Fill procedure a shot before performing expensive repairs.
Customer: replied 5 years ago.

Well, lets see what has happened. I used stop leak and it didn't seem to change. Then I took it back to the propane guys and we exchanged some hoses and fittings. Refilled and re-ran and tried to get air locks out. Then they figured the rad cap was not working properly because it had pressure in the system still when it was ice cold... they figured it should have vented off when colling and the system had no pressure. So I replaced rad cap and am waiting to see if that fixes it. if not, will go to UAP / NAPA and get tool and do the last procedure once and for all.



Thank you for keeping me posted.
Customer: replied 5 years ago.
So changed the rad cap and still same problem. Cannot seem to find vacuum tool anywhere. I'm stumped. Hope I don't have a head gasket leak. Not sure why system is pressurized even when cold - this boggles me. If I open the rad cap when it is stone cold, it is [pressurized and as I unscrew the cap there isa sudden rush of gases into the overflow tank. I left the cap off and brought it up to idle and ran hot and it just keeps bubbling. Don't know what to do anymore. Guess I will have to take to a dealership. Any last thoughts?
As far as a blown head gasket, possible but without any symptoms( white smoke, coolant loss, coolant in oil, etc) I doubt it. I am at somewhat of a loss and can't think of anything else.
Customer: replied 5 years ago.

Hmmm. No smoke. Runs ok when on the road. Idles ok. No oil in coolant. Possible loss of coolant but I think its coming out the back of the overflow tank.


What is weird is that the system is pressurized when cold. I guess the fact it is holding pressure negates that it has a leak of any sort, wouldn't you think?


I have called a local shop and they have the vacuum refill apparatus... just will cost me $40 to have this done. So will take it there next week to get done by them. See if there are any pressure leaks as well. But the fact it is not losing pressure when cold, is telling me there is none...


Think this is occurring because of the propane converter.... don't remember the swishing when i first bought the car and propane wasn't on yet...



good luck!
Customer: replied 5 years ago.

Ok, well here's the finale - what was wrong...


After looking at all the symptoms, being;

- pressurized rad hoses when cold,

- air / liquid surge into overflow tank when loosening cold rad cap,

- constant bubbling off in overflow rad tank when running,

- pressure being maintained when cold and not leaking off,

- no rad fluid on ground, no other apparent leaks,

- no white smoke in exhaust,

- oil not white / opaque,

- rad fluid not brown / oily,

- no pooled fluid near intake manifold gaskets,

- steady (non erratic) idle

- loss of heat in cabin when idling long time

- waterfall swishing sound when cold startup


I used my home gas detector (propane / natural gas / co2) to check the air coming from the rad when I unscrewed the rad cap and it all gushed into the overflow tank. Upon doing this, I got a GAS alarm... so it was propane in the rad and not air... no wonder I could never bleed it out.... propane converter was leaking propane into coolant system. After turning off propane system at tank and re-bleeding system, no more problems. No more gushing sounds under dashboard. Changed propane converter and am running on propane again for last two days - all is gone.


Thought you might like to know.


Thanks for the help!




Thanks for letting me know. I am glad you got to bottom of the issue. I wouldn't of guessed the converter was bad.
Customer: replied 5 years ago.
Apparently the older series of converters had gaskets that got old and wore out. Mine had about 3 years and about 230,000 km on it. It runs pretty hot all the time so this did not surprise me when I figured it out.... anyways - thanks again! Rick

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