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Discussion Starter #1
I just noticed a noise from the front of the engine as RPMs wind down after letting off the throttle. Here's a video link if anyone could identify it, sorry for the vertical orientation. Is it bearings, the supercharger, distributor or something else that I should address?

The truck has 212,000+ miles. I just changed the timing belt, other belts, water pump, spark plugs, and radiator after hitting 200,000. Distributor/cap/rotor wasn't changed though. Also changed oil and filter more recently.

I'd appreciate any help if anyone has heard this before. The truck has been really reliable and I'd love to keep it that way. Thanks.

 

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It's hard to determine just by listening to the YouTube vid. If the noise just started after replacing the timing belt, then you probably have the belt on too tight. There needs to be a little slack in the belt. Correct way to check the tension is with a belt tension gauge, but how many of us actually have one of those? I've done, literally, hundreds of VG timing belts and this is what works for me: once you get the new belt on the cam and crank sprockets and have made sure the timing marks are lined up to the marks on the sprockets, loosen the nut on the tensioner and let it's tension spring take up the slack. Turn the right bank cam gear (on your left if you are facing the engine) about 3-4 teeth counter-clockwise, which will pull the slack towards the tensioner pulley and be taken up. Torque the tensioner nut to 35 lb-ft. Then, turn the right bank cam sprocket about the same distance in the clockwise direction, which will move the slack between the two cam sprockets. At the center point of the belt spanning between the two cam sprockets, use your thumb and forefinger to twist the belt. If it's properly tensioned, you should be able to twist it 90 degrees. If you can't, it's too tight and if you can go more than 90 degrees, it's too loose.
If the noise started well after the timing belt replacement, then I would suspect something else. I suppose you could get a whining noise from the supercharger, but most of the ones I've encountered with bad bearings have made a low-pitched, rattling noise. A bad alternator bearing or idler bearing could also make a whining noise. You could remove the belt and start the engine and see if the noise still exists, which would help isolate the source.
 

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Discussion Starter #4
Wow awesome tips, I'll check those out. But definitely sounds like something with the bearings right?

Are there other bearings aside from the belt-driven pulley wheels and supercharger? I'm thinking maybe the distributor could also have bearings if the sound persists without the belt? Thanks!
 

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Play Doctor and get you a stick or a long ratchet extension or something like that, Put it to your ear and start listening to things it may be. It'll help you find the defective part. Listen to the snout on the SC or maybe further back where the needle bearings are. And of course be careful

Just throwing this out there but at 200k you may need to rebuild that Snout.
 

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I’m not sure about that 1st gen but I find it a little more difficult to try the stets or a rod of sorts on the 2nd gen .. just really tight and down in there. That’s a good idea but be very careful!!
 

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Wow awesome tips, I'll check those out. But definitely sounds like something with the bearings right?

Are there other bearings aside from the belt-driven pulley wheels and supercharger? I'm thinking maybe the distributor could also have bearings if the sound persists without the belt? Thanks!
Yes, the distributor shaft has a bearing. It usually makes a rattling noise when it starts to go bad.
 

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Discussion Starter #12 (Edited)
I finally had time to troubleshoot and try some things you guys suggested :) Used a ratchet extension and confirmed that the supercharger isn't making the noise I'm looking for. I removed the idler pulleys to inspect the bearings, they weren't pretty but not that bad. I just greased them (cleaned up) and reinstalled. Noise was still there though, but I paused to work on something else first because I felt the engine not running smooth when I was driving up a hill.

I wanted to check and calibrate timing because I changed the cap and rotor a month or so prior although the truck felt OK in normal conditions. Except for the hill climb. Anyway while checking with a timing light, the timing marks kept jumping between two or three positions between flashes. I was using a cheap Harbor Freight timing light so I thought that was the culprit. I got a still-cheap-but-a-bit-better Innova off Amazon, but the marks still jumped the same way. I pulled the distributor and it was not spinning smoothly and was a bit hard to turn by hand. There's also small lateral movement on the rotor when I pushed side to side. I should probably replace the distributor, right? Maybe that'll also take care of the noise. Should I go OEM or are there decent reman / rockauto alternatives? Thanks!

314981
 

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IIRC, Gen 1 3.3 distributors are either hard to find (rebuilt?) or OOP. Hope I'm wrong. If not, then buy the most reputable brand would be my best advice. Let us know how this turns out, please.
 

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Discussion Starter #15
I just confirmed my distributor bearings are shot! The trucks does have 212k+ miles already, I don't think the previous owner has changed it.
IMG_2816.JPG IMG_2820.JPG

I almost bought a distributor from Nissan Parts until I realized they were rebuilt units too. So I went ahead and disassembled it to inspect the bearings. I found a thread on the Xterra forums that convinced me it's doable. I disassembled the distributor while still on the truck since I don't have a vice, I just needed screw drivers to disassemble to confirm.

I'm going to look for a local bearing shop tomorrow to get the correct replacements because Amazon or NAPA orders won't be available until late next week. I'll also need an 8" C-clamp to take the bearings off and to set the new ones in. Hopefully it'll be an easy enough fix.
 

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Nissan distributors, alternators and starters are always labeled as remanufactured. Most of the time they are brand new parts just put into a box labeled remanufactured, or at least that was the case when I left Nissan in 2003. Either way, they are just as good as a brand new part and come with a Nissan cap and rotor, as well. I would always go with a Nissan reman over any new or reman aftermarket part. In your case, if the new bearing (and I would replace the shaft seal, as well, if you can find one) fixes it, that's the way to go!
 

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Discussion Starter #18
...In your case, if the new bearing (and I would replace the shaft seal, as well, if you can find one) fixes it, that's the way to go!
Hmmm, I can't find the shaft seal online. I didn't see one on the distributor when I disassembled it, maybe it has disintegrated already too just like the bearings? Oil wasn't going up to the bearings or distributor, I wonder if the shaft is long enough to prevent it from going up. Is there an alternative I could consider, or just run it this way for now and see what happens? Thanks.
 

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Hmmm, I can't find the shaft seal online. I didn't see one on the distributor when I disassembled it, maybe it has disintegrated already too just like the bearings? Oil wasn't going up to the bearings or distributor, I wonder if the shaft is long enough to prevent it from going up. Is there an alternative I could consider, or just run it this way for now and see what happens? Thanks.
I use to have the part # for the seal, but that was a long time ago and I have no idea where I put it or if I have it. I could be wrong, but I "think" it's the same seal that was used in the Hitachi distributors used in early 80's Sentras with the E-series engine? Of course, my memory isn't what it used to be!
 
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