This was my first post here, and im posting it again to see if it can be answered more fully now that i have a better under standing of the sound and where it is coming from. I own a 1987 bronco II 4x4 with a mistubish 5 speed tranny. When i have it idleing and with the clutch pedal out i hear a whirring noise inside the trans/bell housing. I know this is where there are a few bearings, like the throwout bearing, and the trans input bearing. What i suspect it is is the trans bearing, but i cant be sure. Say it was the throw out bearing, would it act like the input shaft bearing and stop rotating and once the clutch pedal is depressed? I put my ear right up to the **** of the shifter knowing the noise would travel trough it and give me a better understanding off the noise and it was loud enough to cuase concern, and dose sound like bearings that are on there way out. Lets assume the worst, it is the trans input shaft, just about how much will it run to get it put in if i brang it to a garage opossed to me removing the tranny and bringing it to the tranny place and have them put the bearing in there and me do all the installing? Can i even do the bearing without needing a tranny place? The only info i have gotten on the clutch was that it has only 30,000 miles on it so i assuming they replaced the throw out bearing as well, so its a good chance its the input shaft bearing unless the throw out was defective. Any info will be very helpful.

 

The release (throw out) bearing is always rotating while the engine is running because the preload spring keeps the bearing pressed against the clutch fingers. When you depress the clutch pedal while parked, however, the trans input shaft bearing should slow down and stop rotating.

If the noise never goes away it's most likely the release bearing.

I just changed mine (I just changed everything clutch-related). The release bearing was bone-dry and made a whirring noise when I spun it, but it wasn't bad enough to notice when installed. It had 173,500 miles on it.

 

yeh so that pretty much means its the input shaft bearing, from what im guessing not to easy to replace. A friend told me you have to split the transmission ( i think it sounds stupid though, im pretty sure a truck transmission isnt in two halves that split apart to get to the bearings) Im pretty sure you buy a bearing puller tool of some sort. Any one else know about this bearing and or what else this niose could be??

 

The input shaft bearing is a know weak spot on the FM 145/146 trannys.the bearing can be replased with out taking the tranny apart.the gay at my tranny shop said you can pull it out useing 2 screwdrivers{ don't know for sure on that].the hardest part is pulling the tranny and reinstaling it.My 89 has the same problem and has had it for about a year and 1/2.The noise will not go away.just get louder.

 

<the gay at my tranny shop said you can pull it out useing 2 screwdrivers>

I know it off topic here, but you did mean guy right? lol. Thanks for the help i think ill replace it only when it gets very very bad. There is a bearing retainer i wouldnt be surprised if the bearings did come out with screw drivers after removing the retainer. Rock auto didnt have the input shaft bearing part listed on there site, do you know its availablity?

 

Yea GUYsometime my fingers go where I don't went them to.LOL!!
When you get it out find a place that sells bearings and match it up.Thats where I found mine.{Bearing,Belts and Drives}