Throw out bearing failure

[tercelwill]

My throw out bearing is starting to act up. I'm getting alot of rumbles and generally terrible sounds from the bell housing. I got a new clutch kit but i have a dilemma. Either I continue to drive around for a month until i can use my buddy's lift. or i do it now on my back.
So my question is what will happen if/when the bearing goes kaput. I've heard the worst case scenario is that the transmission's input shaft could snap.
Does anyone have experience with this happening in a terc. btw its a 85 federal wagon 205k.
Thanks

[4wdchico]

The minimal groveling method would be using a cherry picker and pull the motor to do the clutch if you don't want to wait to use the lift. The only way I would pull the tranny to do the clutch is if I had access to both a lift and a tall tranny jack.

[takza]

Might try to shoot some oil in there if you could hit the bearing...since you will be replacing the clutch? Make sure the bearing does not have continual pressure on it? The only bad bearings I've heard just made a kind of "white noise"...just when the clutch was pushed in.

[4wdchico]

I have been giving your description of terrible rumblings some thought. Does it only do that when you depress the clutch pedal?

[tercelwill]

The noise only ever occurs when the clutch is out such as sitting at a stop light out of gear.
It comes and goes but usually is the worst after 30+ minutes of driving and usually makes a knocking sound but it can very from a high pitched whine like a loose belt and when it is very cold it can sound like stirring gravel. All these noises will go away when the clutch is pushed in.
Is it possible my throw out bearing isn't to blame?

[4wdchico]

Per your description it sounds like the input shaft/gear stack system that transfers the power from the clutch down into the tranny might be failing. The t4wd's crankshaft centerline is several inches higher than the mainshaft of the tranny and the input shaft/gear stack system transfers power down into the transmission. If one of these cars has had it's tranny gear oil run low the input shaft/gear stack system is the first thing damaged as it is the farthest above the gear oil.

The input shaft/gear stack system stops turning when the clutch pedal is depressed and the clutch is disengaged.

[takza]

Yep..not the throwout bearing at all. It's what would be called mainshaft noise in any other transmission. Could be low oil...but it's probably too late....might get by replacing the input shaft bearing as mentioned above.

[Petros]

You can likely drive it with out issues for while longer, but fill up the trans will gear oil. It will make it so it does not get much worse, hopefully. IF it quiets down after you add gear oil to the trans (see the proceedure on a thread in the repair guides), than it was almost surly the input shaft bearing.

It could still be a T/o bearing however, they can make noises at odd times. It can also be the pilot bearing in the back of the crankshaft, that can make a lot of noise too, both are easy checks once you have the trans out. I drove on a bad throw out bearing for a year, if it is the t/o bearing (or the pilot bearing) there usually no bad results in waiting to change it (it is just very annoying). If it is the trans input bearing, best get to it as soon as possible.

Either way the trans has to come out of fix it, might as well replace the clutch while you are at it. let us know what you find when you get the trans out.

Good luck.

[Highlander]

Whoa, Petros- Isn't the input shaft bearing the one that comes out with the input shaft? You can get that out without removing the tranny- but you do need access to the underside of the car. Drop the tail of the tranny down, then It's the three bolts on the firewall side of the trans, then you coax the shaft out, right?

[xirdneh]

Whoa, Petros- Isn't the input shaft bearing the one that comes out with the input shaft? You can get that out without removing the tranny- but you do need access to the underside of the car. Drop the tail of the tranny down, then It's the three bolts on the firewall side of the trans, then you coax the shaft out, right?

there are two input shaft bearings one on the input shaft and one in the front of the tranny
that ones tricky to get out

[splatterdog]

I have a hoist and trans jack. I would still pull the engine for a clutch job.

Lots less dirt and rust in the face that way. Pulling engines on a T4 is done almost entirely from the top.

Plus the pan can be pulled so crankshaft bearings can be measured/replaced.

[tercelwill]

It makes sense it would be the input shaft bearing. I crawled under the other day and found a nice coat of gear oil on the underside of the transmission.

I'm gonna top it off tomorrow with some Lucas additive. Maybe some thick oil will keep it quiet for the time being.

[takza]

There was once a video demo on bobistheoilguy.com of using Lucas additive in a gear train...seems it causes foaming and POORER oil climb up to the higher gears...physical location not gear ratio. I'd only use what Toy specs for oil....since this trans has a lot of VERTICAL.

[tercelwill]

Well i found out you all were right. my trans was WAY low on gear oil. (i should be ashamed. i know)
so i put in a quart of 80w-90 and the Lucas stuff. the noise went away at least for now. hopefully i didn't tear it up too bad.

[Petros]

Good news indeed. That is much less work (and cost) than replacing any of the bearings. Likely any damage was minimal if there are no noises with the proper level of oil. I suspect that a quart low in the 4 quart cap trans axle is not too disastrous if you top it up soon.