I have a 1996 sunfire 2.2L it is totally air locked since putting in new thermostat, please advise


Asked by Jan 11, 2009 at 02:22 AM about the 1996 Pontiac Sunfire

Question type: Maintenance & Repair

Fountain tire installed a new thermostat, broke the bleeder valve, and put in a screw, said they drained air but didn't it overheated. Put on a new coolant pipe with proper bleeder valve and still cannot get air lock out.  Still overheats. Checked all the following and they are all fine: water pump, heater blower, radiator, and no leaks around head gasket.  Re-checked thermostat and it works.  I am a single mom of four and need my car for work. When I was told it was fixed didn't have any heat, then all of a sudden got heat and about 20 minutes later it overheated.  Have taken it to chev dealer and they can't figure it out except they keep saying where bleeder pipe is they have never seen before it is way below motor?

4 Answers

Adam Morgan

hmm... Firstly, replace the radiator cap with a new one to ensure it's functioning properly, cheapest easiest thing it could be. While you've got it off start the car and let it run till it's warm. And then put the cap on. Sometimes air pockets will work there way out while doing this. (make sure you have fluid in the reservoir, a little bit should be pulled in as the coolant cools off.) (Funny thing is I recently read a failure analysis of the GM Dex-cool stuff and most cases were actually traced back to a fault pressure cap stuck open) Air will generally move along to the highest point in the system unless there is blockage... Does your radiator look rusty? Is the radiator clean inside and out? A lot of issues can be solved by running a hose through the fins to clear out dirt and debris(outside of the radiator). Beyond that if everything you said was checked I can't figure out why it'd be overheating... I'll be honest I've never had to deal with any major problems with cooling systems so I'm not the best at troubleshooting. Hopefully someone else will weigh in.

Thomas Daggett

I know how you feel I replaced the heater core, thermastat, water pump, temp sensor and I still have the same issue.


Refill with coolent, start up let run until modestly hot, shut off and remove cap slowly, air will start to fill reservior, liquid level will get sucked into the system, refill and repeat until air lock is removed. I needed three times of starting and refilling until airlock was gone. Sounds like a common problem !!!

1 out of 1 people think this is helpful.

Adam should keep his thoughts to himself. Firstly, there is no cap on a 1996 Sunfire. The factory procedure to remove the air lock is: 1 remove the surge tank cap (and leave off till finished) 2 open the bleeder valves, one on the heater return pipe and one at the water outlet (under the air intake hose). 3 Fill the surge tank until coolant is expelled out BOTH bleeder valves. 4 Close the bleeder valves and top off coolant level (about 1" below the fill neck) 5 Start engine 6 Open water outlet bleeder valve and leave open until solid stream of coolant is expelled then close valve. Repeat this every 3 minutes until the thermostat opens. Note: Thermostat is considered open when the upper radiator hose is hot at the radiator connection. 7 Set heater to full hot and check for warm air during the first 5 minutes. If no hot air start procedure again at step 2. 8 Top off coolant (about 1" below the fill neck) 9 Install surge tank cap

2 out of 2 people think this is helpful.

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