2000 Merc- Rough Idle


Asked by Jul 06, 2015 at 11:47 AM about the 2000 Mercury Grand Marquis GS

Question type: Maintenance & Repair

Replaced my intake manifold and coolant leak is gone ( HOORAY!!) and my car is
running at normal op temp. I have had a rough idle for maybe 6 weeks now ( before
manifold replacement) but it did get worse after I replaced the water pump 3 weeks ago
( then I replaced the manifold and it was cracked- melted-). There is a whine from the
belt area. The belt looks good and I sprayed water as it was running and there was no
reduction in the whining sound. The rough idle is what is now driving me insane.

Any possible ideas?

End note- Could I just be a ninny that didnt tighten my belt properly?

2 Answers


How many miles? How long since sparkplugs have been changed? Is the check engine light on?


The belt idler pulley, or the tensioner could be bad and making the noise. Replace both. The idle could be a lot of things. Were the gasket surfaces cleaned will when the manifold was replaced? spraying gas at the joining points will tell. It will idle smoothly for a while if there's a leak. Replace the plugs also, as per Bob.

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