Text Box: What you will need:

•	GM Check Valve P/N 20876185
•	Pliers or Vise grip
•	Clean empty bottle
•	Rags
•	Air Pump

Symptoms:

The engine temperature rises above 250 degrees at which time the temp warning lamp goes on and/or there is poor heat from the HVAC system.

 

Time to complete:

30 Minutes

 

Cause:

This problem is caused by air bubbles that are trapped in the HVAC system that interfere with the water pump’s ability to circulate the coolant throughout the engine. An obvious indicator is that the coolant level rises above the fill line which is normally the seam of the overflow tank.

 

 

Remediation:

A simple fix is to bleed the HVAC system to eliminate the air bubble.  There are many methods to accomplish this but the simplest is shown below.

 

Although this may solve the problem, in many cases, the air bubbles are re-introduced into the system in a short period of time.  To correct, this, GM has released an air check Valve intended to eliminate the air bubble.

 

Pontiac has released a TSB for this condition and the fix is quite simple.

 

 

2013-03-30 15.35.13-2

 

A clear indicator that there is air in the system can be seen by observing that the coolant level in the overflow tank is above the “Full level” (the seam  on the tank)

 

2013-04-28 09.52.43

 

Obtain GM air check Valve P/N 20876185

 

The price for this piece varies between $7-28 Plus shipping depending on where you purchase it.  An internet search will reveal several sources.

 

You will need to order two of these devices

 

 

https://lh5.googleusercontent.com/-35jYFDEL6sE/UVdUKsF74jI/AAAAAAAAB98/tX4T3R6Cj0Y/w430-h322-p-o-k/cool2.jpg

 

 Set the heat knob in the car to full heat.

 

Disconnect the small hose on the top of the overflow tank and insert hose into a small clear bottle. Make sure the bottle is clean and dry.

https://lh6.googleusercontent.com/-Gd4SA2Lrtbs/UVdUMfCJ-qI/AAAAAAAAB-E/yzo2g2cje_k/w430-h322-p-o-k/cool3.jpg

 

With a cold cooling system, lower the coolant level enough so  that when removing the coolant return hoses from the cylinder head and radiator return ports coolant will NOT leak on to the ground or on surrounding components.

 

Pump a shot of air into the tube on the top of the overflow tank. You will hear a gurgling noise through the top of the engine and at some point the coolant will start to spurt into the clear bottle.

 

 

 

Remove the coolant overflow hose from the engine, save the clamp; you will need it to reattach the hose.

 

Using a non-silicon based tire lubricant, lightly coat the check valve (P/N 20876185) and insert it in to the engine return hose (1) 15 mm (0.5 in) in the hose with the tapered end pointing toward the nipple that is on the engine.

 

Press the hose on to the nipple and seat the hose to the base of the fitting. This will push the valve in to the hose.  You will see a bulge in the hose in the middle of the bend.

The valve should not be pushed in the hose to the point that it is in the horizontal position. A check valve in the horizontal position will not function properly.

 

Install the hose clamp on the hose and reinstall the hose

 

 

Now we will repeat the procedure on the coolant return hose from the radiator. As before, remove the clamp from the hose and set it aside so it can be re-installed later.

 

Remove the hose form the Radiator. 

Note: pull the hose in a straight motion. Excessive side pressure result in a broken radiator nipple.

 

Using a non-silicon based tire lubricant, lightly coat the check valve  and insert it in  to the radiator hose return line 15 mm (0.5 in) in the hose with the tapered end pointing toward the

radiator nipple. Press the hose on to the nipple and seat the hose to the base of the fitting. This will push the check valve further in to the hose resulting in a slight bulge in the hose.

 

Install the hose clamp on the hose and reinstall the hose on the radiator return

 

https://lh6.googleusercontent.com/-uTwZtitXWMU/UVdZioq0A7I/AAAAAAAAB_Y/0hac27K5TOQ/w497-h373/cool4.jpg

 

Add coolant to the "Full Cold" line of the bottle and replace the cap.

 

Purge air from the system by injecting air into the overflow tank as shown above. Again, you will hear a gurgling noise through the top of the engine and at some point the coolant will start to spurt into the clear bottle.

 

Remove the cap again and add more fluid the "Full Cold" line of the bottle and repeat this procedure unitl there is no more air in the system.  When you are done, the fluid level should be even with the seam on the overflow tank.

 

Replace the hose on the top of the coolant reservoir. Inspect the cooling system for leaks. Rinse away any excess coolant from the engine and the engine compartment

 

Verify the procedure was successful by taking the car for a ride while keeping an eye on the temperature in the DIC .  The engine temperature can go as high as 220 degrees and then the fan will turn on.  The temperature should go back down to between 190-205degrees  as you drive.