Hissing noise - Jeep Wrangler JK.

[JKBall]

Originally Posted by Hayesio

Hi mate.

Try this: with the car stationary, in neutral, engine running, leave you door open and press the clutch in and out, in and out. Listen for the noise. Or better yet, get the missus to do this while you get down to the clutch housing and listen.

If the noise goes away when pressed in but comes back wthen released - its almost certainly the release bearing. This is a relatively common problem for JK's petrol and diesel alike. Mine, diesel, does it, and yes it's annoying. But don't be too alarmed, its not imminent failure - mines done it for 3 years now.

What makes the sound is when there is almost no pressure on the release bearing from the clutch fork against the spring/pressure plate in combination with the bearing having a little bit of play in it. The balls are able to "rumble" around a little bit. This "rumble" causes vibration through rest of the bearing assembly and against the clutch spring - which makes it louder. As soon as you apply pressure, the inner and outer races are compressed together, balls are aligned into the races and walla, no noise.

I'm betting they didn't change the release bearing when they did the clutch - dealerships are know for tight-a*sing on this.

Hi Hayesio,

I'll do you test tomorrow, with my girlfriend, but I can tell you now that I've pretty much performed this test by default in the past few days, without the need to have the door(s) open or my girlfriend assisting. I can hear the hiss/noise coming and going while the Wrangler is stationary, in neutral, engine running and pressing the clutch in and out.

Not an imminent failure, but progressively, with time, gets worse?

Not being rude or forward but you've had friends, who've owned JK's with the same or similar issue and or had the release bearing replaced and the noise/issue has been fixed?

The noise you hear/have heard from your JK, what would you describe it as? A hiss or a rattle or clunk or something similar?

If a brand new release bearing is installed, would it have any "play"? Or is that something that is caused by wear and tear?

Well due to the hiss/noise still being present after the extensive inspections and services last month, I would say you're correct that the release bearing wasn't changed when the new clutch was installed.

Thank you for your advice and input Hayesio. I may have several more questions for you in the coming days. I hope you don't mind.

[Hayesio]

I think it's really a design issue with the sach bearing they use - it's crap in my opinion. Maybe try getting another brand, not sure but I think there are a few available for the 3.8ltr. I've gone through 3 now, the first made the noise, the second didn't, and the last one is - bad. I've also though in the past that it might also be related to the spring tension or the fork clip tension. But these are all pretty simple parts, not really any adjustment that can be made.

I know a couple of guy with it, but I often here the noise on others jeeps when out on the trail or with the club. Have a look around the American sites, i've seen post there in the past.

The noise sounds like a loose worn bearing without lubrication racing around, a metallic hiss really.

Another thing you should try to confirm that this is the problem is just to put a little bit of pressure on the clutch pedal - just a little bit - don't disengage the clutch. If the noise gets less or disappear altogether - this is it.

[JKBall]

Originally Posted by Hayesio

I think it's really a design issue with the sach bearing they use - it's crap in my opinion. Maybe try getting another brand, not sure but I think there are a few available for the 3.8ltr. I've gone through 3 now, the first made the noise, the second didn't, and the last one is - bad. I've also though in the past that it might also be related to the spring tension or the fork clip tension. But these are all pretty simple parts, not really any adjustment that can be made.

I know a couple of guy with it, but I often here the noise on others jeeps when out on the trail or with the club. Have a look around the American sites, i've seen post there in the past.

The noise sounds like a loose worn bearing without lubrication racing around, a metallic hiss really.

Another thing you should try to confirm that this is the problem is just to put a little bit of pressure on the clutch pedal - just a little bit - don't disengage the clutch. If the noise gets less or disappear altogether - this is it.

So do you recommend the Jeep/Mopar replacement release bearing or another aftermarket brand?

Your first release bearing also made a hissing noise? The other guys you know who have had the same or similar issue, they could also hear a hissing noise?

A loose worn bearing without lubrication racing around, a metallic hiss - being the release bearing, just to confirm?

I'll also perform this second test, a little bit of pressure on the clutch pedal test, tomorrow.

Again, thank you for your help.

[Banshee]

They aren't all bad, but some people have had a bad run of them. Mine was fine for ~150,000km, but I had to replace the clutch at that point, so got a Centerforce kit from Morris that came with one included.

This is the bearing that is between the clutch slave cylinder & the rotating pressure plate. Throw out Bearing

So, if in neutral & stationary, you can hear the noise then it goes away as soon as you put pressure on the clutch, but not enough to release it completely, and the noise goes away, then this is a likely suspect. If you have to press hard enough to disengage the engine & gearbox, probably not.

[JKBall]

Hayesio,

To confirm, you're confident the mechanical part causing the noise and issue is the release bearing?

its almost certainly the release bearing

As other members have mentioned it's the throw out bearing? Or are they the same bearing with two descriptions/titles?

So, if in neutral & stationary, you can hear the noise then it goes away as soon as you put pressure on the clutch, but not enough to release it completely, and the noise goes away, then this is a likely suspect.

Yes, virtually the same instructions as to what Hayesio gave in the 9th post...

[JKBall]

So I just spoke with the mechanic who worked on my JK last month. He confirmed that he replaced the release/throw out bearing with the new clutch kit (as the release/throw out bearing was included in the new clutch kit package) and replaced the spigot bearing.

He also re-raised his third point that due to the nature of Wrangler JK drivelines the hiss is normal and that a Jeep Australia technician confirmed this for him...

Back to square one...

[JKBall]

So no-one has any more refined opinions what could be causing the noise/issue? Given my above post regarding my conversation yesterday with the mechanic who worked on my JK last month.

Also, I plan to have several upgrades installed on my Wrangler in the next few weeks. Bull bar, 2" suspension/lift kit, wheels and 285/70R/17 tyres.

Would installing the above upgrades worsen the issue or increase the hissing noise?