Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSMERCURY2009MILAN PREMIER, 3.0 1, AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1677 (ENGINE SYSTEM - GENERAL INFORMATION)DIAGNOSTIC TESTSENGINESYMPTOM CHART - ENGINE PERFORMANCE

2009 Mercury Milan Premier, 3.0 1, AWD

Symptom Chart - Engine Performance

2009 Mercury Milan Premier, 3.0 1, AWDSECTION Symptom Chart - Engine Performance

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Condition	Possible Sources	Action
Difficult starting	Inoperative or damaged ignition system Air or vacuum leak Inoperative or damaged fuel system Inoperative or damaged starting system	Refer to the appropriate Engine article for the procedure. REFER to the Introduction - Gasoline Engines article.
	Damaged charging system/battery	REFER to CHARGING SYSTEM - GENERAL INFORMATION article.
	Burnt valve	INSTALL a new valve in the cylinder head. TEST the system for normal operation after the repair.
	Worn piston	INSTALL a new piston. TEST the system for normal operation after the repair.
	Worn piston rings	INSTALL new piston rings. TEST the system for normal operation after the repair.
	Worn cylinder	INSTALL a new cylinder block. TEST the system for normal operation after the repair.
	Damaged head gasket	INSTALL a new head gasket. TEST the system for normal operation after the repair.
	Inoperative or damaged cooling system	REFER to ENGINE COOLING article.
	Fail-safe cooling invoked (if equipped)	REFER to the Introduction - Gasoline Engines article.
Poor idling	Vacuum leaks Inoperative or damaged EGR system	Refer to the appropriate Engine article for the procedure. REFER to the Introduction - Gasoline Engines article.
	Inoperative or damaged ignition system	REFER to ENGINE IGNITION - 4.6L (2V) article.
	Inoperative or damaged cooling system Inoperative or damaged fuel system	Refer to the appropriate Engine article for the procedure.
	Fail-safe cooling invoked (if equipped)	REFER to the Introduction - Gasoline Engines article.
	Damaged hydraulic lash adjuster	INSTALL a new hydraulic lash adjuster. TEST the system for normal operation after the repair.
	Incorrect valve-to-valve seat contact	INSTALL a new cylinder head. TEST the system for normal operation after the repair.
	Damaged head gasket	INSTALL a new cylinder head gasket. TEST the system for normal operation after the repair.
Engine runs rough	Inoperative or damaged fuel system Air or vacuum leaks EGR system fault Inoperative or damaged cooling system Inoperative or damaged ignition system	Refer to the appropriate Engine article for the procedure.
	Fail-safe cooling invoked (if equipped)	REFER to the Introduction - Gasoline Engines article.
	Damaged hydraulic lash adjuster	INSTALL a new hydraulic lash adjuster.
	Burnt or sticking valve	INSTALL a new valve in the cylinder head. TEST the system for normal operation after the repair.
	Weak or broken valve spring	INSTALL a new valve spring. TEST the system for normal operation after the repair.
	Carbon accumulation in combustion chamber	ELIMINATE carbon buildup. TEST the system for normal operation after the repair.
Excessive oil consumption	Leaking oil	REPAIR oil leakage. TEST the system for normal operation after the repair.
	Inoperative PCV system	REPAIR or INSTALL new components as necessary. TEST the system for normal operation after the repair.
	Incorrect oil	CHANGE oil to correct specification. TEST the system for normal operation after the repair.
	Worn valve stem seal	INSTALL a new valve stem seal. TEST the system for normal operation after the repair.
	Worn valve stem or valve guide	INSTALL a new valve and valve guide. TEST the system for normal operation after the repair.
	Sticking piston rings	REPAIR or INSTALL new piston rings. TEST the system for normal operation after the repair.
	Worn piston ring groove	INSTALL a new piston and piston pin. TEST the system for normal operation after the repair.
	Worn piston or cylinder	INSTALL a new piston or cylinder block. TEST the system for normal operation after the repair.
Oil in coolant	Leaking head gasket Leaking oil filter adapter or gasket Damaged cylinder block Damaged cylinder head	INSPECT the engine components. INSTALL new engine components as necessary. Refer to the appropriate Engine article for the procedure. TEST the system for normal operation after the repair.
Coolant in oil	Leaking head gasket Leaking oil filter adapter or gasket Damaged cylinder block Damaged cylinder head	INSPECT the engine components. INSTALL new engine components as necessary. Refer to the appropriate Engine article for the procedure. TEST the system for normal operation after the repair.
Insufficient power	Inoperative or damaged ignition system Air intake system blockage Lubrication system blockage Inoperative, blocked or damaged fuel system	Refer to the appropriate Engine article for the procedure. REFER to the Introduction - Gasoline Engines article.
	Oil level too high	DRAIN oil to correct level.
	Incorrect engine oil	INSTALL correct specification engine oil. TEST the system for normal operation after the repair.
	Excessive accessory drive belt loading Inoperative or damaged cooling system	Refer to the appropriate Engine article for the procedure.
	Fail-safe cooling invoked (if equipped)	REFER to the Introduction - Gasoline Engines article.
	Damaged or plugged exhaust system	INSPECT exhaust system.
	Incorrect tire size	REFER to SUSPENSION SYSTEM - GENERAL INFORMATION article.
	Dragging brakes	REFER to BRAKE SYSTEM - GENERAL INFORMATION article.
	Slipping transmission	REFER to DIAGNOSTIC TESTS article.
	Malfunctioning hydraulic lash adjuster	INSTALL a new hydraulic lash adjuster. TEST the system for normal operation after the repair.
	Weak or broken valve spring	INSTALL a new valve spring. TEST the system for normal operation after the repair.
	Worn or damaged cam	INSTALL a new camshaft. TEST the system for normal operation after the repair.
	Damaged head gasket	INSTALL a new head gasket. TEST the system for normal operation after the repair.
	Cracked or distorted cylinder head	INSTALL a new cylinder head assembly. TEST the system for normal operation after the repair.
	Damaged, worn or sticking piston ring(s)	REPAIR or INSTALL a new piston ring(s). TEST the system for normal operation after the repair.
	Worn or damaged piston	INSTALL a new piston and piston pin. TEST the system for normal operation after the repair.

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.