Milky Radiator Fluid

[Tabone777]

On my 67 C10 I have noticed a milk substance inside my radiator. I initially thought headgasket or cracked head. I have checked my oil dipstick and looked inside of the oil filler cap and have not seen any water or milky substance visable. But I noticed that my trans fluid was low. I now think my trans cooler line is leaking into the radiator.I called a radiator shop and was told the radiator could be repaired and flushed. My queston now is will i have to get the whole transmisson flushed after the radiator is repaired? I did not notice any milky substance on the transmisson dipstick either.

[MT1972cheyenne]

Your transmission pressure is much higher than your cooling system pressure, so the fluids would only go 1 way. Transmission fluid would go into radiator, but no coolant would go into transmission.

[Tabone777]

Thanks so much for the reply. That is a big relief...

[69 gmc]

Yeah i have noticed the same problem on my truck

[MARKDTN]

Originally Posted by MT1972cheyenne

...Transmission fluid would go into radiator, but no coolant would go into transmission.

Until you turn it off and then the pressure in the radiator is higher. You need to address this immediately! If you get water in the transmission it is already too late. The water attacks the glue on the clutches and they come apart. Found this out first hand on a '71 Eldorado. The TH425 FWD transmission is basically a TH400 with a chain drive from the torque converter to the pump. This problem requires a new transmission cooler. A radiator shop can take the tank off and replace it, but if the radiator has any age you may be better off just replacing it, or having it recored at the same time.