Tapping & Vibration Sound From Driver's Side Valve Cover | Ford Explorer Forums - Serious Explorations

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Tapping & Vibration Sound From Driver's Side Valve Cover


Active Member
March 18, 2010
Reaction score
City, State
Amory, MS
Year, Model & Trim Level
1998 Mountaineer AWD
I have a 1998 Mountaineer with the 5.0L V8. It has about 186,000 miles.

It's had a slight exhaust leak for awhile, but just recently we've noticed a tap-rattle that seems to be coming from inside the driver's side valve cover. I let a retired mechanic friend hear it and he thought it sounded like a lifter knocking, but didn't think it was serious.

Now in the last couple of days, it seems to be getting more noticeable. Anyone experienced anything like this?

I'm about to attempt to remove the valve cover and see what I can find. Are the valves adjustable?

Any ideas or advice is welcome. Thanks in advance!

Sounds like a sticky or collapsed lifter. Change the oil and filter and substitute a quart of oil for a quart of ATF in the oil and drive it around normally for a few hundred miles. Keep checking the oil. If it gets dirty replace it and the filter again. I bet the noise goes away. I also recommend using 0W30 mobile 1 synthetic oil. (Cheap at walmart) It's pretty close to operating viscosity at 100 degrees and isn't any thinner than 10w30 at operating temperature. Much less wear and tear while starting and warming up the engine and it really seems to help with sticky lifters.