Car Problem Reports

Mercury Mountaineer Rough idle when cold due to upper intake manifold gasket leak

Mercury Mountaineer Problem
7 Reports
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Model Years Affected: 1998, 1999, 2000, 2001

Engines Affected: 4.0L V6, 4.0L V6 SOHC, 5.0L V8

Average Mileage: 182,300 mi (158,000 mi - 206,600 mi)


TheĀ Check Engine Light will illuminate and the engine will idle roughly when cold. There are updated upper intake manifold gaskets to resolve the problem.

  • Visitor, , 5.0L V8, 206,600 mi

    High idle (approx. 1700 rpms)and check engine light came on.
    Had it diagnosed, shop said it was due to leak at manifold gasket. Idle increased to compensate for the leak. Repair estimate - $400
    I was told in my case it is not a bad leak and can be delayed until it gets worse.
    I will wait.

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