Tranny/clutch rattling. Any help appreciated.

[Joe72Mart]

My 91 S10 in sig has developed a rattling noise from either the transmission or the clutch. Not very loud, but noticeable. I've googled this issue to death and ended up overwhelmed with (mis) information.

Here's the problem: Slight rattling noise at idle (with foot off the clutch and in neutral) and while driving. Just slightly touching the clutch pedal eliminates it completely. So far I've read: pilot bearing, throwout bearing and trans input bearing are causes. What do you think? Truck has extremely low miles and has all original clutch and related parts. Could the throwout bearing be rattling in its mount? Help.

thx in advance for any suggestions.

Joe

 

[Rand]

generally speaking I would be thinking throwout bearing.

but to fix just about all that it needs to come apart.. so does it really matter?

 

[eljefino]

Jack up the rear and run it in first at idle. If it's still chattering I think it would be one of the trans bearings.

 

[bruno]

You have checked the fluid level I assume ?

 

[NHGUY]

I bought a new 1989 S10 2.5/5 speed back in the day,and 7000 miles later it developed the rattle/squeak.At 21,000 miles I had the clutch replaced due to the noise getting louder.The shop called me up once they got it apart and said the cone on the front of the transmission had a groove wore into it (this cone guides the T/O bearing) and the diaphram fingers on the clutch cover were wore 1/2 way thru.My take on this was/is the hydraulic system would not allow proper freeplay at the bearing and it was rotating the bearing every engine revolution for those 21,000 miles.Eventually the bearing overheated,went dry and locked up.Hence all the damage.I had the clutch replaced,couldnt find a new cone anywhere in stock,and traded the thing in on a new 93 Dodge car.One garage came up with a grease fitting fix for part of the rattle....supposibly it allowed grease at the fork pivot which would (I guess) wear and rust causing the dry squeak.Wouldnt have made a difference in my case.

 

[TallPaul]

If the throwout bearing is okay and the transmission does not have a bearing going bad, and if it specifies ATF, then I wonder if a slightly thicker lube would help, maybe like Redline MTL would help. ATF is terribly thin.

 

[Joe72Mart]

Originally Posted By: bruno
You have checked the fluid level I assume ?


Changed and checked. Filled with M1 ATF. Has been serviced every few years.

thx bruno

 

[Joe72Mart]

Originally Posted By: Rand
generally speaking I would be thinking throwout bearing.

but to fix just about all that it needs to come apart.. so does it really matter?


True. But how quickly? Will this rattle for a year or does it need changed ASAP?

Thx Rand

 

[Joe72Mart]

Originally Posted By: eljefino
Jack up the rear and run it in first at idle. If it's still chattering I think it would be one of the trans bearings.


Will try that tomorrow.

thx for the feedback eljefino

Joe

 

[beast3300]

Throw out bearing.

 

[Joe72Mart]

Originally Posted By: beast3300
Throw out bearing.


thx beast

How long can I drive it like this? I know that's tough to answer, but will it gradually fail? Or will the T/O grenade and leave me stranded?

Joe

 

[Joe72Mart]

Originally Posted By: TallPaul
If the throwout bearing is okay and the transmission does not have a bearing going bad, and if it specifies ATF, then I wonder if a slightly thicker lube would help, maybe like Redline MTL would help. ATF is terribly thin.


Run all Redline MTL or a mix of ATF and the Redline?

Joe

 

[Trav]

Quote:
Just slightly touching the clutch pedal eliminates it completely

That almost completely eliminates the pilot bearing.
Pilot bearings get louder with the clutch pedal fully depressed.
It could well be the input shaft bearings but it's also possible there is something sticking in the slave cylinder causing the clutch fork to hold the throw out bearings (which are usually loud under load when worn out) to rest on the clutch fingers and cause noise.

Does the clutch come far up before it grabs?
Try changing the fluid in the clutch for a start.

 

[aquariuscsm]

It`s just your transmission`s internals spinning. Every manual transmission car I`ve ever had has done that. If it was the throwout bearing,it would squeal when you *press* the clutch pedal. Check to make sure all dust boots,etc underneath the shifter are secured.

 

[Joe72Mart]

Originally Posted By: Trav
Quote:
Just slightly touching the clutch pedal eliminates it completely

That almost completely eliminates the pilot bearing.
Pilot bearings get louder with the clutch pedal fully depressed.
It could well be the input shaft bearings but it's also possible there is something sticking in the slave cylinder causing the clutch fork to hold the throw out bearings (which are usually loud under load when worn out) to rest on the clutch fingers and cause noise.

Does the clutch come far up before it grabs?
Try changing the fluid in the clutch for a start.


Thanks for the response and advice Trav

It is the original clutch M/C and slave. I have siphoned off and replaced fluid in m/c. Never have bled the slave.
Clutch is engaging in the same place as always, probably about half way up. Bleeding the slave may be problematic, since its never been done.
BTW I always read your posts-most informative.

I'll try to bleed the slave, it could very well be hanging up after all these years. Perhaps even a replacent is due.

Why would a slight touch of the clutch pedal quiet things down?

thx Joe

 

[Joe72Mart]

Hi aquar.

I would agree with you about some manual transmissions being noisy. But this rattling just started recently. My understanding of t/o bearing is the same as yours. Loud when failing under load-like when it's pushing the fingers of the PP. This noise stops with just a slight push of the clutch pedal. Just the opposite. I'll crawl underneath and check out the hardware you mentioned tomorrow.

thx Joe

 

[Bluestream]

A bad throw out bearing will squeal when you touch the clutch pedal, or push it in. It will stop when you release the pedal. (unless pedal is not adjusted properly and the throwout bearing is always turning)

It will get progressively louder as the bearing wears out; Can't do a whole lot of harm unless it seizes. It has to be fixed so you may as well do it now if you have the cash...

 

[Trav]

Quote:
Why would a slight touch of the clutch pedal quiet things down?


When you depress the clutch slightly you load the clutch fork which presses the throw out bearing against the clutch fingers a little firmer.

I am a firm believer in doing the cheapest possible thing first especially things that can be considered good maintenance.
It could be a number of things but eliminate the small stuff like clutch transmission fluid first.
It has been posted that this is normal noise, its true there is a fair amount of noise associated with the normal operation of rotating assemblies, but it sounds from your post that this rattle noise has not always been there.

If everything checks out okay i would try something like this before opening anything up.

http://www.lubegard.com/~/C-269/LUBEGARD+Gear+Fluid+Supplement

 

[Joe72Mart]

Originally Posted By: Trav
Quote:
Why would a slight touch of the clutch pedal quiet things down?


When you depress the clutch slightly you load the clutch fork which presses the throw out bearing against the clutch fingers a little firmer.

I am a firm believer in doing the cheapest possible thing first especially things that can be considered good maintenance.
It could be a number of things but eliminate the small stuff like clutch transmission fluid first.
It has been posted that this is normal noise, its true there is a fair amount of noise associated with the normal operation of rotating assemblies, but it sounds from your post that this rattle noise has not always been there.

If everything checks out okay i would try something like this before opening anything up.

http://www.lubegard.com/~/C-269/LUBEGARD+Gear+Fluid+Supplement


Hello again Trav:

We must think alike! I actually bought a bottle of lubegard red (since transmission specs ATF) at O'Reilly's when I first noticed the noise. Emailed them for a dosage rate. They said try about 4 ounces and see if it makes a difference. It does shift a little smoother now, but didn't do anything to quiet the noise.

The truck is 21yrs old and I bought it new. It has plenty of squeaks and rattles, but I can notice an additional one quickly. The transmission did not make this noise until just a few weeks ago. I thought at first it was something belt driven since it varied with speed. Than one tap on the clutch ID'ed it.

thx for the advice
Joe

 

[mechtech2]

Input bearings make different noises with different symptoms.

Your light touch on the pedal to stop this noise strongly indicates a throwout bearing.