I think this has been in the works for awhile, but it just escalated. May or may not be related, but I've had an occasional whine coming from what seems like the tranny bellhousing area, though I know sounds can telescope. It changes with rpms.

I was hoping it was a pulley bearing or something, but now I don't think so. Yesterday I started hearing a kind of grinding noise. I can even feel it a bit in the stick shift. It just started yesterday so I haven't pinned down all the specifics, but what I know so far: The grinding happens in gear, clutch pushed in. I notice it when putting it in first when I'm at a stop light or parking. When I let out the clutch, it immediately stops. Mostly wondering whether it sounds more like a tranny or clutch bearing issue.

Any thoughts?

 

It does sound like a throwout bearing by your description, if so it should make noise every time you push the clutch in regardless if in 1-3 or neutral, there are Aisin kits available still for these trucks. How many miles on the current setup?

 

/\ /\ /\ Most likely, it's also possible it's the pilot bearing, both are in motion only when the clutch pedal is down with the engine running. I'm sure it's possible to figure out which one in particular it is, but basically, you're pulling the trans and replacing both of them and the clutch (and RMS) while it's apart anyhow, so it doesn't matter.

 

Alright, thanks! Yeah exactly, if it's clutch-related, it'll all get replaced. The grinding I've only heard in first, with clutch in. Doesn't mean it isn't happening other times, but that's the only time I've heard it. And it doesn't happen every time. Hasn't happened at all today. What's been happening off & on for at least a year now is when I push in the clutch, I hear a high-pitched whistling noise, mostly on acceleration. Always when I have the clutch in. But just like the grinding, it comes & goes.

Anyway, if it's clutch time, it's clutch time. 313,000 miles on the original! And I've been towing a 3,000 pound trailer quite a bit for the last 100,000 miles. Hard to complain. I'll look at part prices and start seeing what friend is willing to loan me garage space. The question now is whether to look at the tranny while it's out...I'm all for not fixing what ain't broke, but even though pulling a tranny isn't complicated, it's definitely a pain. At this mileage I wonder whether rebuilding it is worth it. Finances might be the deciding factor more than anything else, I guess.

 

Grinding noise is not good you may need to peek in the inspection cover sooner then later, could be a broken clutch spring or pressure plate lever floating around the bellhousing, best to pull the drain plug aswell and see how much metal is on the magnet and brass in the oil to make a judgement if further investigation is required. A TOB usually only makes noise with clutch depressed, most notice it parked and pressing the clutch to better hear it.

 

While I'm at it...I'm worried that I have a few things going on. There's the grinding noise I described above, which is obviously the throwout bearing. But another noise that's been coming & going for a while longer is more of a whining/groaning noise, which changes with rpms, and is starting to be more constant. It happens no matter whether the clutch is in our out.

I'm starting to think input shaft bearing. Anyone have experience diagnosing one of these? Kind of sounds like a go-cart. I've rebuilt a transfer case in the past so it's possible I'm up for replacing the input shaft bearing, but obviously that's a lot more work to plan for, and lot more downtime for the truck to plan for. I don't want to get in there to do the clutch and find a loose input shaft, so I'm wondering if anyone has experience with known input shaft bearing noise to help me decide how likely it is that I should be ready to replace it along with the clutch. And I guess whether I should buy an entire bearing kit for the transmission. My trailer-pulling is finally catching up with my truck....

 

If the truck is motionless and the tranny is in gear, the noise cannot emanate from the transmission because under that circumstance,
everything in the transmission is at rest.

 

So that would mean clutch in, truck not moving? I was thinking the shaft was always spinning, but as I try to picture it, I guess 'clutch in' is the one time it's not spinning. But it would be spinning in neutral with the clutch out, correct?

So where should I be focusing on for a noise that changes with rpm (not speed), and happens no matter the clutch position? Could a pulley bearing transmit noise so it sounded like it was coming from the bellhousing? I've never heard pilot bearing noise before but to me this noise doesn't seem like it could come from such a small bearing. I did basically submerge the truck in dry sand last spring. So I wondered if any exterior engine stuff would fail...Otherwise...a bearing inside the engine? If the noise doesn't go away this time I'm not against getting it diagnosed at a shop. It's just hard to schedule an appt 4 weeks out and hope the noise is happening then.

 

Yes, in neutral and with the clutch out, some of the tranny internals are rotating.

 

The input shaft, the layshaft gear cluster, and all of the gears on the output shaft are still meshed and spinning too. The output shaft isn't turning.

All of the gears are constantly in mesh and turning, they're just selectively locked to the output shaft, presumably one at a time.

4th gear is a special gear, that's the only one where engine torque doesn't go through the input shaft gear, into the layshaft cluster, and back up to the output shaft - it simply locks the input shaft to the output shaft, producing a 1:1 'gear' ratio.

 

So I can't rule out transmission bearings then, if the noise happens regardless of clutch position, or am I misunderstanding?

 

With the truck stopped, the output shaft isn't turning.

With the clutch out and it in any gear, with the truck stopped, nothing will be turning in the trans. The throwout bearing (pressing against the pressure plate) and the pilot bearing (between the input shaft and the end of the crank/flywheel) are turning.

If it's in neutral,even with the clutch out, the input shaft and most of the trans internals may or may not be turning (other than the output shaft). There's a certain amount of drag between the clutch and pilot bearing, this can sometimes spin the trans even with everything working properly. But usually, in neutral, engine running, car not moving, you can hear the trans parts stop turning if you push the clutch down.

So you have to be a bit systematic in doing different things and listening for the noise.

1) Engine running, car stopped, clutch out, in a gear (just to make sure nothing is spinning in the trans), is it making a noise? Could be throwout and/or pilot bearing. If not, the noise is likely coming from the trans.
2) Put it in neutral and let the clutch out, does the noise stop? Points to the TO/pilot bearings. If it starts at this point, likely a trans issue
3) As you drive, is it making a noise? Does it change with engine RPM or vehicle speed? Does it change on accel/decel? Does it change in the various gears? Noticeably absent in 4th (possibly 5th)?

It's really hard to diagnose something from a description of a noise. And cars are usually making multiple noises, some good, some bad, some in between.

 

Got it, thanks. Seems like there's a chance it could all be clutch-related, but I'll need to wait till the next time it's happening and pop the hood to see if it's actually coming from a pulley.

It definitely makes the noise with the clutch out, parked, while I'm warming it up. Worse in cold weather. Changing with rpms, not vehicle speed.

 

That sure sounds to me, for what it's worth, after having owned an 87 4Runner for more than 25 years, like a idler pulley bearing is worn. I don't know HOW many of those I replaced over the years. They are cheap, easy to replace, and easy to access. A long screw driver, and a pair of "ears", or hard shelled hearing protectors, and you can check each bearing quickly eand easily. Touch the screwdriver bit to a bearing, and the handle to an ear, and check for the sound. If you hear it loud and clear, you've found the problem.

I don't know if an idler bearing IS the source of the noise, but it was a common problem, especially starting in cold weather, in my Runner. Most every idler bearing I had had been replaced several times, and that's how I found them. I also took the belt of my AC, so it was never a problem.

Have fun!
Pat☺

 

Thanks Pat. I saw the screwdriver trick on a youtube video and I plan to try that soon.

 

Pretty sure the noise is the idler pulley. The power steering pulley has a little play, and makes more noise than the alternator, but the idler pulley has a lot of play and worse noise. I've got one on the way so we'll see if that takes care of it.

Then of course I need to plan when to replace the clutch....

 

The awkward unbalanced bulk of the transmission and transfer case makes it a bit of a bear to pull to get at the clutch.

 

Yeah I remember that. It's been a while, but I had the transmission on my 83 out multiple times. I don't remember it being fun.

In other news, the idler pulley was definitely the source of the noise I was chasing down. Glad it wasn't input shaft or other internal tranny noise.