Engine Cooling

Oil/Coolant Mixing - Diagnosing Source of Leak

A few days ago, returning home from a long trip (without any problems) the temperature on my 83 S Euro suddenly starts to rise really quickly. Just before it reaches the red zone, I pull over, turn off the motor, leaving the key in the position where the electric fan continues working. The fan runs for about 1 minute and stops, but in the meantime a lot of smoke comes out of the engine compartment. Also some coolant comes out from the tube on the expansion tank with something mixed that I didn’t want to believe was oil, but it was in fact. I was about 10 km from home and after letting the car rest for about 1 hour I decided to take it home, watching the temperature that during that distance did not pass the last white mark, open windows and heating on maximum. At home some more coolant on the floor (with oil) but no more smoke. A few hours later when I check the coolant reservoir it was in fact a lot of oil mixed with the coolant but the engine oil was perfect or at least it seemed it was only oil. The fact is that after three days stopped the engine oil is now with a lot of coolant too.

Do I have a head gasket problem or as someone told me is it possible that the oil /coolant mix can be happening in the radiator? Although both possibilities are a really big problem I think it would be easier to change the radiator than changing the head gaskets. Is there a way to know and confirm what is the problem in fact before starting to take the engine apart?

Thanks in advance for your help ad/or suggestions.

Ricardo Pires
Portugal
83S Euro 5 speed



The failure could be in either place. The overheating makes me think that a head gasket is more likely, but it is possible that the engine oil pumped into the cooling system could lower the cooling efficiency enough to cause overheating.

The easiest way that I can think of is to disconnect both oil lines going to the radiator at the engine. Go to a bicycle shop and buy an inner tube for a tire. Cut the tube, and clamp one cut end over each of the oil lines (Empty the cooler first.). This will allow you to apply compressed air thru the bicycle tube valve stem, and pressurize the oil cooler with no chance of damaging it thru over-pressure. (The bicycle tube will limit the amount of pressure to a low level - if it explodes, you put in too much air!)

Fill the coolant tank before you pressurize the cooler, and leave the cap off. Watch in the tank for air bubbles or movement of the liquid. If there are no bubbles or movement after several minutes of pressure, the leak is probably not in the cooler.

Good luck!

Wally Plumley
928 Specialists