Wertbe

My '98 Pathfinder has recently started making an alarming sounding racket, from the lower end of the engine. As the title suggests, my thoughts go towards worst case scenario and say its a rod knock in its early stages. I've recorded a video of it, which is the worse the noise has been so far, and iirc the engine was at full operating temp. It's not quite as loud or deep as bad rod knock is, but that's why I say it could be in the early stages. It could be attributed to piston slap, but as far as I know, that sound would go away when it warms up, plus this sound has been happening for maybe 3 weeks now, as opposed to the 3 years that I've owned it. The youtube channel 'Auto can' has a series of videos diagnosing a vg33e knocking sound, and it turned out to be the keyways on the timing belt sprocket and crankshaft being very deformed, allowing the key to rattle around when running. I don't know if I'd rather have that than rod knock but it could be that as well considering how relatively quiet the noise is? One additional thought I had about this was that according to the maintenance records I have, the timing belt was done at 103k miles, and it now stands at 170k miles. Technically less than Nissan says to replace the belt, but not out of the possibility it needs replacing and could be contributing to the noise, right? I should also mention that I went on a quick drive before posting this, getting it to operating temp for around 15 minutes. Neither when it was idling cold nor after the drive did the noise come up, it sounded just as it did before the concern arose. I don't know what that means but probably good to know. This car was very nicely garage kept and maintained for most of it's life before I had it, and while sadly it did experience a decently big front end collision (that didn't immediately affect any mechanical components), I have been very on top of oil changes and other maintenance items, so it's very frustrating to see the engine potentially going to crap, especially so long before 200k miles.

Didn't see this until now, but I came to the same conclusion. When I first opened up the distributor completely, there was dust and metal shavings everywhere, and a single exploded bearing. I'm guessing the debris got the ICM sensor dirty and sent faulty signals. I don't know how thoroughly I was able to clean it, but I took a duster can and sprayed it in the slot for a few seconds, after also changing 5/6 spark plugs (I wasn't able to get to the 6th one) and spark plug wires. It seems to be running good, for now. Have you seen issues related to that bearing before? Your response denotes past experience with this exact issue.

Hey y'all, new to the forum. I've been having a frustrating issue with my '98 SE lately, which really came out of nowhere and so suddenly. I was driving on the highway one day (70 mph cruising if it matters) and noticed it started to stutter slightly every once in a while, something I've never noticed before. A couple days later on that same highway, it went from a slight stutter to very apparent misfiring very quickly. The max rpm I could get the engine to progressively shrank as time went on, eventually getting to the point where it wouldn't even start. After doing what I could in a remote area, I noticed there wasn't a spark when I did the old screwdriver-stuck-in-spark-plug-wire trick. Naturally, I replaced the distributor cap/rotor and an ignition coil (they were cheap). After replacing the ignition coil, it seemed to have fixed the issue, running and revving like normal while parked. However, when I tried driving it around, the same thing started happening within minutes, and I barely was able to limp it back home. While diagnosing fuel pressure, I noticed that the engine will sometimes 'snap out of it' and idle perfectly smooth at 1k rpm, and when I rev, it goes wild again. I don't think it's a fuel issue because 1: the missing spark I mentioned earlier, 2: a new ignition coil seemed to help, 3: using a fuel pressure tester reveals the pump is giving a steady 35-40 psi. I've only been able to take out the right bank of spark plugs (the ones not covered by the intake manifold), and they look due for replacement, with very apparent wear patterns. But with what I mentioned about the periodic smooth running, it makes me think there is a sensor issue somewhere. There hasn't been any check engine light to indicate a faulty sensor though. TLDR: Engine doesn't run smooth, rpm maxes out way too low. New ignition coil temporarily fixed it, but quickly reverted back to rough running. No check engine light, and steady fuel pressure, my instincts tell me it's an issue somewhere in the ignition circuit. I tried recording what is happening. Sorry for the shorts format, youtube formatted it like that. https://youtube.com/shorts/OvFNfK1ecIw This one is where I discovered where it sometimes will run smooth at 1k rpm, you can hear my confused "what?" https://youtu.be/pndj0Tl-8nA As I usually am when I come to forums for help, I have no idea what to do next.