Cat C9 coolant high pressure

[Dale Malquist]

I have  2007 Contessa that is pumping the coolant out through the overflow. Right pressure cap and not overfilled. 54000 miles and suspect a bad head gasket or worse. Any one had this problem? Cost?

[Robert Mathis]

I had the same problem on my 2005 Ford F250 6.0 PSD. Under a heavy load or heavy acceleration, I would smell coolant and could see where it was blowing out the overflow bottle. It turned out that this was caused by the heads "bouncing" and letting compression into the coolant system. On your Cat, it is most likely an head gasket problem causing the overpressure in the system. Have you tested the actual pressure in the system with a radiator pressure guage? If not, that would be the first place to start. It just replaces the radiator cap and measures the pressure. There is also a test strip to detect combustion gasses in the coolant, and the definative test will be a compression test.

[harry kew]

Maybe have your air compressor checked, I have changed a few air compressors where a seal starts leaking into the cooling system,pressurizing the cooling system on truck application.One of the ways to check is to pull your filter off your air drier and see if there is signs antifreeze.