Running on 7 Cylinders

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03-15-2015, 03:44 PM

#11

Rokgtar

2nd Gear Member

Join Date: Apr 2008

Location: Va

Posts: 380

Quote:

Originally Posted by BlindGUYnAR

The rotating assembly on that cylinder is moving regardless of the spark plug or injector is plugged in or not.

If it was a mechanical noise the noise wouldn't go away by unplugging those in my opinion.

Look for an exhaust leak.

Not entirely true. By pulling the plug, it will stop the cylinder from firing. That can stop the load on that cylinder just enough to stop the noise when a rod bearing is spun.

I know because my 4.6 had a knock; pulled the plug on #4 cylinder and it went away. I verified that the bearing was spun upon disassembly.

03-15-2015, 04:51 PM

#12

BlindGUYnAR

2nd Gear Member

Join Date: Apr 2014

Location: AR

Posts: 236

Quote:

Originally Posted by Rokgtar

Totally agree, but since it has headers a leak is a real possibility so wanted that checked. Since the sound is there at times and not at others the exhaust leak is less likely.