Re: How Do I Determine if Coolant is in Engine Oil?

Al Bundy wrote: 
KC wrote:

I think coolant is contaminating my van's engine oil.

The oil on the dipstick looks black as it should, the oil on the bottom
of the filler cap was more brown than black, but not milky. The engine
slowly loses coolant over a period of 30 - 45 days. The temp gauge
never climbs, but I know the coolant level has dropped because the
heater starts blowing cold air when the engine as at idle. You only get
warm air if the car is being driven. I never see any leaks, or find any
coolant on the ground. The cooling system was pressure tested. The
mechanic said it held the pressure fine. The vehicle is a 1998 Ford
Windstar with the 3.8L engine, 140,000 miles.

My questions:

1. Is the oil on the bottom of the filler cap telling me the coolant is
in the oil?

2. Would I have to send an oil sample to be analyzed to be absolutely
sure the oil is getting contaminated?

3, If the mechanic determines that coolant has been contaminating the
engine oil for the past few months, would I be tossing money away to
get the van fixed due to damage the coolant may have done to the
engine?

Thanks in advance for any advice 


You don't say how much coolant you are losing, but presumably it's a
lot. It doesn't sound like you have coolant in the oil because of the
color and amount. It could be a head gasket and not show in the oil,
but the pressure test should have revealed that. You say there are no
leaks. So everybody is suspect here. Start over.
Maybe you have a leak in the coolant reservoir that would not show up
the pressure test at the radiator, but the rest of the system would
hold water.  Keep looking for leaks and maybe take it somewhere else. A
water pump could leak a tiny bit and not be noticed and in some cases
could pass a static pressure test. Check that extra closely.


Don't forget that a weak radiator pressure cap can cause a slow loss of coolant with no visible trace. The coolant is lost as vapor instead of liquid because the cap doesn't hold enough pressure to prevent it from slowly boiling away.

.

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