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Signs of head gasket failure SUBARU Impreza IV Hatchback (GP) (10.2011 - ...)

@walter.howard
13.05.2025 11:05
Member

Hey everyone, I’m driving a 2015 Subaru Impreza and recently noticed white smoke from the exhaust, engine overheating, and milky oil.


Could these be signs of head gasket failure? Any advice on diagnosing or fixing it would be greatly appreciated!


Started

13.05.25

Latest reply

17.06.25

Replies

3

Views

39

  • @Graziana Venturi
    13.05.2025 13:51
    @walter.howard
    AUTODOC expert
    Yes, white smoke from the exhaust, engine overheating and milky white oil may indicate a bad cylinder head gasket. This occurs when coolant enters the cylinders and mixes with the oil, causing the characteristic symptoms.
    It is recommended to have the vehicle diagnosed immediately and not operate it to avoid serious engine damage.
  • @L.💂💂💂
    17.06.2025 16:54
    Member
    The symptoms you describe on your 2015 Subaru Impreza—white smoke from the exhaust, engine overheating, and milky oil—are classic signs of a head gasket failure. Here's why and what you can do:

    Signs Indicating Head Gasket Failure
    White Smoke from Exhaust: This usually indicates coolant leaking into the combustion chamber and burning, which is a common symptom of a cracked or blown head gasket.

    Engine Overheating: A failing head gasket can cause coolant loss or mixing, leading to inadequate cooling and chronic overheating.

    Milky Oil: When coolant mixes with engine oil due to a head gasket leak, it creates a thick, frothy, or milky substance, which can often be seen under the oil filler cap or on the dipstick.

    Additional Symptoms: Loss of coolant without visible leaks, rough engine idle, engine knocking, or bubbles in the radiator when the engine is running can also indicate head gasket issues.

    Diagnosing Head Gasket Failure
    Visual Inspection: Check the oil filler cap and dipstick for milky oil.

    Compression Test: A mechanic can perform a compression or leak-down test to detect loss of compression caused by a blown head gasket.

    Coolant System Check: Look for bubbles in the radiator or coolant reservoir when the engine is running (only when cool to open safely).

    Coolant Flush and Air Pocket Check: Some mechanics find trapped air pockets during coolant flushes that suggest a head gasket leak.

    Repair Advice
    If confirmed, the head gasket should be repaired promptly to avoid severe engine damage such as cracked engine blocks or engine failure.

    Repair typically involves removing the cylinder head, replacing the gasket, and inspecting the head and block for warping or cracks.

    Given Subaru's history with head gasket issues in various model years, including Impreza, it's advisable to have the repair done by a knowledgeable Subaru specialist.
  • @L.💂💂💂
    17.06.2025 16:54
    Member
    Your 2015 Subaru Impreza’s symptoms strongly suggest head gasket failure. Immediate diagnostic tests like a compression test and inspection of the oil and coolant systems are recommended. If confirmed, timely head gasket replacement is necessary to prevent further engine damage.
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