Rod knock noise coming from engine

HBCAPTAIN

MEMBER
2000 NISSAN XTERRA
3.3L
V6
2WD
AUTOMATIC
142,600 MILES

Loud lifter or rod tapping on drivers side of engine. I first thought it was a collapsed lifter so I installed a new Nissan set even though the old ones seemed fine. No change. Then I checked the rod bearings sure to find one bad. They looked great, all within tolerance, but I installed a new set anyway. Put it all back together noise still there. Been driving it with the OBDII hooked up and found the noise comes and goes with ignition timing. Driving easy the advance is thirty four to forty two degrees noise is loud. The harder you drive it the quieter it gets. WOT adv at eighteen degrees no noise. Heavy acceleration adv at 20 to 28 degrees no noise.
Can the ECM be the problem by advancing the timing too much? It is a metal to metal noise. Definitely not a pinging octane type noise.

3 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning.

Disable one cylinder at a time and see if that makes a difference. If it does then it is possible you have a bad piston.
When you did the rod bearings, did you plastic gauge the bearings?
Did you drop the mains and check them as well?

No the ECM will not cause a engine knock.

Roy

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Tuesday, February 6th, 2018 AT 2:44 AM

HBCAPTAIN

MEMBER
2 POSTS

Thanks for the quick reply. I did plastic gauge the rod bearings, all at.0005 to.001. Did not check the mains. I disabled each cylinder individually, noise goes away with cylinder no 6 disabled. A bad piston meaning sloppy in the cyl or rod/piston connection?
Two things the engine does that I am baffled by; when driving in any gear it is totally quiet below 1600 rpm and at any rpm when the ignition timing is not too far advanced (around 25'BTDC or less) The knocking is completely gone.
Thank you in advance for all your help.

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Tuesday, February 6th, 2018 AT 10:09 PM

ASEMASTER6371