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.

Assuming the radiator hoses are ok and you are not getting an unusual
fogging of thge interior windows I would check the following:

1. The reservoir is a very good place to start. I had one develop
microscopic cracks that would open up only when the engine was good and
hot, otherwise they were invisible and closed.

2. Check closely around the thermostat and hose connections for any
sign of dried coolant.

3. If the radiator has a plastic tank, check the return pipe for
cracks.

4. Check all heater and bypass hoses and connectors for leaks. Some
of them will be hard to see completely, but persist.

5. Check the pipes on the heater core for cracking. They are likely
made of plastic these days.

.

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