I have a 2001 Infiniti QX4 (similar to pathfinder), with about 2006,000 miles on it. I've developed a rattle that is hard to pinpoint the location. Changed the oil, still makes noise. What could it be? Here's a video of the noise.
https://www.youtube.com/watch?v=CV5k1F-1kOc
Noisy Engine
Moderator: volvite
I wouldn't think it's the fan clutch; they will either have the bearing go bad and will wobble around or the clutch will stay engaged and make a "roaring" noise like a propeller driven airplane.
There are a few possibilities on these engines. They did have problems with the power valve screws that hold the butterfly valves to the shaft fall out due to insufficient loctite. The screws would sometimes drop and bounce around on top of the valve or they could fall into the combustion chamber. If it's the later, they sometimes get pounded into the soft aluminum cylinder head or they could bounce around for a while, potentially gauging the cylinder walls and/or damaging the piston. It could be timing chain noise, possibly due to low oil pressure or a component failure. An issue with the VTC system, which I doubt but is still possible. I would recommend not running the engine any more than you have to and don't rev it up. You might have to do some teardown if the problem is not obvious. It's kind of hard to give you much more advice just based on what I can hear on the video. If you want to eliminate the possibility of a fan clutch or drive accessory, just remove the belts and start the engine.
There are a few possibilities on these engines. They did have problems with the power valve screws that hold the butterfly valves to the shaft fall out due to insufficient loctite. The screws would sometimes drop and bounce around on top of the valve or they could fall into the combustion chamber. If it's the later, they sometimes get pounded into the soft aluminum cylinder head or they could bounce around for a while, potentially gauging the cylinder walls and/or damaging the piston. It could be timing chain noise, possibly due to low oil pressure or a component failure. An issue with the VTC system, which I doubt but is still possible. I would recommend not running the engine any more than you have to and don't rev it up. You might have to do some teardown if the problem is not obvious. It's kind of hard to give you much more advice just based on what I can hear on the video. If you want to eliminate the possibility of a fan clutch or drive accessory, just remove the belts and start the engine.
When doing the oil change, I noted that my girlfriend put more than 5 quarts of oil in. So possibly that could have done something. Yesterday the alternator died, and the noise went away. Replaced the alternator, no noise. Coincidence maybe, but the sound didn't seem to come from that area. Hopefully the noise doesn't come back. Thanks for the input, I'll look into those screws once the weather is good again.
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