Car has 107000 miles, 4 cylinder 2 liter auto. Noticed when car is shut off there is a large amount of air bubbling up through the overflow tank. There is no antifreeze in the oil, and does not use oil. Rad & system has been flushed. Plugs are burning normal with no signs of any antifreeze burning, no white smoke from tail pipe. Added leak seal can, and rad holds pressure. Not sure why the bubbling back to the reservoir. Any suggestions on source to look for this and should I be concerned? Worst case is my worry of a head gasket failure pending? Car has been doing this for a year or about 8000 miles. Car did not run hot (overheat) in the summer.
I had a leaking rad hose so I changed it this summer (pin hole leak) and did the thermostat at that time. Engine appears to run normal temperature summer and winter.
I was guessing that if air was in the system, and it gets expelled to the overflow tank, it is out of the system and can not get anything but fluid back in. Not sure where the iar pocket would come from?
February, 1, 2007 AT 10:31 PM
Found an interesting item on the car today. The rad cap tested and holds 15 psi. However the top of the rad cap had antifreeze on it around a rivet (or pin though the cap face) and when I tried to blow though, I could.
Is it possible the rad pressureizes, fills the overflow tank but when it cools and the pressure goes off instead of sucking antifreeze from the overflow tank, I just get air though this top of the cap?
February, 2, 2007 AT 4:08 AM
The Rad cap is a small price to pay then an hourly labor. For future use you can get a cooling system pressure tester. Then you can advertise within the neighborhood on professional cooling system check it'll pay for it.