Racket After New Clutch Install

Team,

Recently I installed a new clutch kit, flywheel, and rear main seal on my
2016 Tacoma 2.7L 4x4.

Within 1000 miles, I began to notice an intermittent racket when I came to a stop, shifted into neutral, then let off the clutch pedal and reengaging the clutch. I also hear it when driving slow next to close objects that allow the sound to echo back, such as cars, fences, buildings, and some curbs.

The racket stops when I depress the clutch pedal and release the clutch. Reengaging the clutch makes it come back.

It’s really noticeable when my A/C is running. Each time the A/C compressor kicks on, the racket is at its worse.

I made a couple videos to listen to. They’re posted on YouTube.
(if there’s a more efficient, effective, or easier method to share videos, let me know)

https://youtube.com/shorts/hZxpehzlcQ0?feature=share

https://youtu.be/NVwFVXA2Sjc

Any insight before I tear back into it will be greatly appreciated!

 

Sounds like the throw out bearing to me.

if you just lightly engage the clutch petal, enough to just press the TOB into the clutch fingers *slightly* and it goes away….that’s usually it.

If that’s it, it could just get louder with the AC kicking on due to the additional drivetrain load or vibration frequency or something.

 

Check for a worn thrust bearing, it would allow the crankshaft to move forward and back in the block - not good obviously.

Watch the crankshaft front pulley as the noise comes and goes, see if it appears to move.

A strobe light might help spotting it if you could find one.

Thrust bearing on left and a regular main bearing on the right.


Thrust bearing installed, it rides close (oil clearance) to the machined surfaces of the crankshaft.
Note the clearance - this one is badly worn, the normal clearance is around .004.

 

I would say throw out bearing
What parts did you use?
Did you replace the throw out bearing?

 

Always start with the last things/areas you last touched before the issue….always. Venture out from there if needed.

 

I purchased and installed the following kit and flywheel. It included release and pilot bearings, disc and pressure plate. I took extra care in further packing the bearings too.
https://www.ebay.com/itm/1326952863...3WCs983RH6&var=&widget_ver=artemis&media=COPY

https://www.ebay.com/itm/1333776538...3WCs983RH6&var=&widget_ver=artemis&media=COPY

I’m leaning against it being the release bearing, but will troubleshoot it to make sure.

Now, I hate to admit this, but I’m sure I pulled a rookie mistake when doing this job. I had a heck of a time separating the bell housing from the engine. Obviously I didn’t have it aligned and supported axially, causing the input shaft to bind up. A few times I’m certain the entire weight of the transmission and transfer case were being supported by only the input shaft stuck into the clutch assembly.

I’d like to know all the potential ramifications of allowing that to happen.

Based on that, the thrust bearing theory scares the crap outta me, but could make sense. What about the bearing on the input shaft?

 

Hopefully it’s the throw out bearing. I see your location is Portland, if that’s Oregon not Maine then you are welcome to borrow my transmission jack. Just PM me.

 

If the transmission input bearing is bad usually the noise will immediately go away when the clutch pedal is pushed with the transmission in any gear and the vehicle stationary.

In this situation there is nothing moving in the transmission.

When releasing the clutch pedal in neutral a bad input bearing will be heard spinning right up to engine speed.
Usually it is kind of a wisssssh sounding noise - if that makes sense.

 

Properly adjusted the release bearing will usually be silent until you push the clutch pedal.

By design it clearances itself from the pressure plate when you release the pedal.

 

My concern is the noticable increased noise with the AC cycling.

(Sorry for the multiple posts, difficult for me to edit with the phone. )

 

[QUOTE="
Usually it is kind of a wisssssh sounding noise - if that makes sense. [/QUOTE]

Yeah there’s no whisssssh sound. Just the knock knock knock racket. Possible it’s nothing more than an A/C compressor? Or are you still leaning towards a thrust bearing? I would think that’d eventually lead to oil leakage from prematurely wearing the front and rear main seals, yes?

I haven’t looked for axial deviation in the crank yet. This weekend hopefully.

To provide a little more context, I was well equipped with a 1-ton hydraulic transmission floor jack with fore and aft tilt. I used two ratchet straps to secure the jack and transmission together. They’d become one. But when slowly lowering, constantly adjusting the tilt to accommodate, the front wheels of the jack lifted off the floor. The tilt knob, which turns a screw on the aft end, was obstructed and in contact with the transmission. I raised it back up and loosened my straps. Some time later after wrestling this thing, lowering the jack again, all contact was lost with the transmission. I immediately raised it back up. This happened twice.

 

I tested the release bearing theory by pushing the clutch pedal down only fast enough to make contact with the pressure plate. There was no deviation in sound at all.

Prior to replacing the clutch, the release bearing was indeed worn. I was getting a very annoying chirping sound. Push the clutch pedal just a tad, the chirping stopped.

 

I mentioned the thrust bearing as something to check and eliminate - hopefully not leaning that way...

When they get excessive clearance they wear exponentially faster until - when the softer face of the bearing wears away and the crankshaft starts hitting the steel backing of the bearing things go bad much faster - the oil leaks are the least of your problems at that point...


The AC compressor clutch bearings can go bad causing it to be noisy when the AC is off and it should be freewheeling. The clutch can also lock up causing the AC compressor to turn all the time.

The AC compressor itself can go bad causing noise only when it is engaged (AC on), when not engaged the compressor isn't turning, the clutch freewheels on the bearings mentioned above. If the compressor locks up the belt will smoke (perhaps stalling the engine at idle) when the AC engages.



You can remove the belt from the engine and run it briefly to see if the noise changes, you will have several warning lights on the dash probably but you won't damage anything running the cold engine for a minute or two for a test.

You can also use a broom stick, pry bar, etc to listen for noises like a stethoscope - they make actual stethoscopes for mechanics too, I have always just used whatever was handy.
Put one end where you want to listen, put the other end against that little pointy thing on your ear -- the "Tragus".
If you have never done this you might be surprised how well the noises telegraph up the stick/bar/etc.

Obviously don't stick the other end into something moving.

 

I just happen to have one retired and one active RN in the family, so an actual stethoscope should be easy to acquire. I’ll give that try, paying close attention to where I stick my hand! Haha. Thanks for idiot-proofing your message. One just never knows exactly who they’re dealing with.

In all seriousness though, I surely appreciate you sharing all your experience and expertise.

I’ll first try the listening method in an attempt to pinpoint the source of my sound. If inconclusive, maybe even just for shits and grins, I’ll start the engine up from cold with the serpentine belt off. That’ll also allow me a closer look at the crankshaft pulley to check for any wander.

All are things that I wasn’t thinking up to check any time soon. So thank you. I will be posting my findings soon!

 

@KetchupOnMyTaco

Any progress to report?

 

RustyGreen, good sir!
Thank you much for checking up on me.

I’ve nothing to report as yet, for I’ve been terribly busy wrapping up a college affiliated internship. Writing final reports, creating PowerPoints, and submitting appraisals.
Meetings mixed everywhere in between.

Took my son camping in central Oregon last weekend. Drove my girlfriend’s XTerra.

Still driving the Tacoma plenty. Milder weather equals little A/C usage. When I do though, I’ll periodically poke my head under to hear the racket. I got the stethoscope on my passenger floorboard. Waiting to commit a morning to run though the different troubleshooting you gave.
Wasn’t this weekend, once again.

Jotting all this down, jogged my memory. I’ve one observation to report: I changed my oil a few weeks back, first change since servicing the clutch. My racketing knock sound seemed to lessen. Still only noticeable when A/C runs, but it’s severity improved some.

I don’t know if I mentioned, when I had the rear main seal and retaining plate off, I selectively followed the sections of YouTube videos I agreed with, while also referencing my Hayne’s manual (more on that later). I gently scraped all the cured RTV I could before taking Brillo pad to the mating surfaces to finish the cleaning. Well, while scraping a larger piece of unknown size fell inside. Unknown because it was sqeezeout that sat over a lip on the inside of the crankcase, and was under oil that was dammed clear up to that lip. I tried for an hour to fish it out, but was unsuccessful. I’ll guess and say it was 5x10mm, possibly having a stringy tail hanging from one end.

I read every article and discussion I could find. Read a few horrific stories of engine failure. But most suggested the RTV would likely settle on the bottom of oil pan, to spend into eternity.

But this knock I have while A/C pump kicks in, leaves me forever concerned I’ve a blocked oil gallery that feeds the right-side of the engine. I say right, because that’s the side where the sound is more dominant.

Yeah, I need to stick that stethoscope all over under there, sooner than later.

Can I ask what you meant when you mentioned using a strobe to check the crank for axial movement?
My search online was inconclusive.

Oh, the Hayne’s manual! Despite its cover printing claiming third gens are covered, they are not! It’s hardly usable even to reference. That’s all I have to say about that.

 

Good to hear from you , sounds like you have a lot going on.

A stroboscope is a tool which uses a bright flashing light to allow a user to view objects which are rapidly moving in a periodic manner. When the frequency of the flashing light is matched to the speed of the object, the object can appear to be stationary.
https://www.instructables.com/Stop-Time-with-an-LED-Stroboscope/

If the crank were moving back & forth you might be able to see it by watching the distance between a fixed point near by.

This is the style we use in industrial settings, you adjust the strobe rate until it matches the speed of what you are point it at.
You can read the part number on a moving belt, obviously the number is going round & round - the strobe will make it appear to be standing still.

 

Well, I’ve had the belt off twice now. First time was to have a listen with a stethoscope. That was inconclusive, as I wasn’t getting the knocking sound to occur. Perhaps the system wasn’t worked enough from the drive in cooler temps. While it was off, I was able to pick a single point of reference to hold a steady eye and watch for axial movement in the crank. I couldn’t see any deviation.

Just yesterday, I replaced the belt, idlers 1 & 2, and the tensioner idler. That quieted things down immensely. I will have to continue to watch for the knocking as time progresses, and especially as we move into warm weather next year. Until then, I’m considering the situation to be steady.

 

Good news!

The idlers & tensioner do wear out and can make quite a bit of noise.