Coolant in oil 55 Cadillac 331 engine

[Bob Kielar]

Hello all,
                      I sent a oil sample to a laboratory and the results came back stating there is some coolant in the oil. The engine runs great there is no steam coming out of the exhaust and my oil looks like oil not milky at all. I was thinking of putting pressure in the radiator with the thermostat out and see if the pressure holds. Any thoughts would be appreciated.

Regards,
Bob Kielar

[R Sotardi #11719]

Knowledge is power, follow through with your pressure check. Then add a can of Barsleak if the coolant leak is minor.

[Coupe]

You should also check for bubbles in the coolant in the radiator. That can be an indicator of a leak.

One thing to consider when you do the pressure check is how much pressure you put on the system especially if the heater is not bypassed. I learned this the hard way on my '57. I blew apart the rubber hose connection inside the heater box at the Ranco valve when I went for just a little more PSI. Not a fun project taking that apart and putting it back.

[Mike Josephic CLC #3877]

Did the testing company tell you how much coolant (% or ppm) was in your
oil?  In a car of that age with an original engine, a few ppm's of glycol
in the oil would not surprise me.  (ppm's = parts per million).  Ask them what
the sensitivity of their test is (detection limit). 

A coolant gas test would quickly show if there is CO2 (carbon dioxide) in
your cooling system.  Any competent garage can do this check. 

If CO2 is present that indicates exhaust gasses getting into the cooling
system via a head gasket leak.  Have that test done and you'll know better
where you stand and how bad the leak is, if indeed you have one.

Mike

[PHIL WHYTE CLC 14192]

Hi Bob,
I saw this on the Ikes and meant to reply, but got tied up with other stuff. Anyway I have used a "block tester" which draws water from the top of the radiator and if the chemical that you have in the tester changes colour then you have engine gasses in the cooling system. This was very accurate on my 331 engine - it diagnosed a cracked cylinder head. I believe that you left the car standing quite a while - they can get condensation in them and that could be the simple answer. You can also do the pressure test on the cooling system. I bought my Block Tester on line - it is a USA made tool and my neighbour bought his from the Snap On man - this was here in England.
Phil