Skip the auto shop - Our mechanics make house calls

Q: Severe coolant loss

asked by on

Severe coolant loss from coolant reservoir. No apparent leaks or liquid anywhere near vehicle. Engine overheats at idle. Highway speeds vehicle is at normal operating temperature. Milky white substance in oil fill tube on engine

My car has 200000 miles.
My car has an automatic transmission.

A "milky white substance" is an indication that coolant and engine oil are mixing. In all likelihood, you are losing coolant but not seeing it leak anywhere because it is leaking into the oil pan, mixing with - and thinning - the oil to create that milky substance. This can be caused by a head gasket gone bad, or possible a cracked cylinder head. This will cause the engine to overheat as well. Prolonged driving with the coolant and oil mixing will damage the engine internally. The engine may be running cooler at highway speeds due to the increased air flow though the engine compartment. To reduce the risk of damaging the engine beyond repair, it should not be driven and this coolant leak should be inspected by a certified technician, such as one from YourMechanic, as soon as possible.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I have rough idle and shaking

The idle air control motor is powered and controlled by the engine computer. You will only get power and ground when the computer wants it to move. If the engine computer is not controlling it, then you may have a...

Q: Car jerks

What you are describing sounds like a dirty or faulty mass air flow sensor. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays vital information...

Q: Brake Pad on passenger side is heating up.

The brake caliper and/or the sliding pins in the caliper bracket, are sticking. Typically, when brakes are refurbished, if the existing calipers have 75,000 or more miles on them, they should be replaced with high quality remanufactured calipers to avoid...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.