Land Rover Repair: Diagnosis, gasket leaks, antifreeze leak

Question
Good Morning John,

My question is a general one...not really related to land rovers.   I have discovered motor oil in the antifreeze recovery tank on my high mileage 92 mercedes 190e 6cyl. I just noticed it today after replacing the uppr and lower radiator hoses.
I refilled the antifrez and notice some brown drops in the tank.  Later the antifreeze in the recovery tank was brown and I dipped my finger in there and it smelled like motor oil...I know its bad to find oil here...but what has likely happened?  History...not long ago I discovered an antifreeze leak and traced it back to a dying water pump ..replaced that.  no sign of oil then. however the engine does leak alot of oil prob a quart in a months time.

Answer
Hello Robert,

Not being familiar with your fine vehicle, there may be a few scenarios that could explain this problem.  

I suspect that the oil cooling line, that runs thru your radiator, may have a leak and is infiltrating into the coolant area.  You've changed the rad hoses and perhaps there is a link between the oil and coolant lines.

Its possible that some small amounts of oil, which you state is being lost by a quart/month, could have dribbled into the coolant reservoir.  IF the oil amount that is mixed into the coolant is a significant amount then either the first or the last scenario is more likely.

It is possible that your engine block gasket has a leak and oil is being forced into the coolant area.  Usually, with gasket leaks, the coolant mixes in with the oil and is obvious in the oil sump tank, however, in your case the oil is penetrating into your coolant area.  Just in case, check your oil to see if it has a light brown or coffee-like froth.

Best of luck,

JohnMc