There are a few possibilities; The fluid in overflow could be engine oil and the head gasket is bad. Check Engine oil for a white, milky substance which would further confirm this diagnosis.
The transmission cooler is leaking. It is integrated into radiator and can leak a red or light red fluid into the anti-freeze. Transmission fluid would have red, milky fluid in it if this is the case.
October, 3, 2011 AT 10:13 AM
Ok, so there is no milky substance in the engine oil, will I have to change the thermostat housing to solve this problem, please advise?
October, 3, 2011 AT 10:17 AM
Hi, there is no milky substance in my engine oil, So will I need to change my Thermostat housing to solve this problem.
October, 3, 2011 AT 10:32 AM
The thermostat is isolated in the cooling system. It runs around 15 PSI while oil pressure runs around 60-80PSI. So it takes a heavily torqued gasket to seal out the oil from the thermostat.
The thermostat gasket is just to keep anti-freeze from leaking out of engine.
In the head and water jacket passages of the engine, are areas where the 2 fluid circuits come close to each other. If a head gasket fails near the oil circuti it tends to either leak into the anti-freeze circuit, which can over-pressurize it and you may notice extra coolant in the overflow, or in the cylinder where it will make the exhasut have a burnt oil smell. If the Anti-freeze circuit leaks it leaks down into the oil pan by way of return passages that are under residual pressure.
If anti-freeze gets in the cylinder the exhaust smells sweet like anti-freeze and is generally white.
So, I think from what you are desribing, and the reason I mention the above, is that the only way to have cross contamination is to have a crack in the engine block or to have a bad head gasket. The thermostat seal has nothing to do with sealing either fluid circuit from each other.