Bad pilot or input shaft bearing -how long till trans blows?

general bacardi · Post by **general bacardi** » Fri Jan 20, 2006 10:17 pm

I have a 93 Legacy L wagon with 170K miles. At idle, it makes a low pitched rumbling sound, and the sound dissapears when you push the clutch in. The noise is not very loud. Also, while driving around town, the car makes kind of a scrapey/whiney gear noise. The whiney noise is most pronounced when you shift into first while moving. (The noise might be present at freeway speeds, but I can't tell due to the wind noise from the mirrors.)

I changed the tranny oil, I found a few tiny silver metal flakes on the drain plug magnet (much smaller than the head of a pin), but nothing major. The oil was relatively clean.

I did a search on the drivetrain forums, and it sounds like the noise at idle is being caused by a bad pilot bearing or input shaft bearing.

Can the pilot bearing be replaced relatively easily? (i.e. can it be done without completely pulling the engine apart?)

I take it the input shaft bearings are located inside the tranny, so if those are bad, it's time for a new trans - right? Is there a way to diagnose whether it's the pilot bearing or input shaft bearings that are going bad?

If the tranny needs to be replaced, how involved is the labor? Is it possible to replace the trans without completely removing the engine from the car?

If I can find a good used tranny, about how many hours of shop labor would it take to swap them? I try to do most of the work on my cars, but this might be too big of a job for me...

Given these symptoms, how many miles of driving could I expect before the tranny self-destructs? Unfortunately I just got the car, so I don't know how long the noise has been present.

entirelyturbo · Post by **entirelyturbo** » Sat Jan 21, 2006 5:26 am

I don't think pilot bearings make that kind of noise (dunno for sure), but it's pressed into the back of the crank; it supports the tranny input shaft. There's a way to get it out by forcing a thick liquid into the crevass behind it, and it will be forced out.

Post by **Legacy777** » Sat Jan 21, 2006 7:24 am

I'd suggest replacing the pilot & throw out bearing. If the input bearings need to be replaced, you'll have to take apart the tranny.

The pilot bearing can be replaced by taking off the flywheel and tapping the bearing out from the back side.

entirelyturbo · Post by **entirelyturbo** » Mon Jan 23, 2006 2:34 am

Bah, I thought the pilot bearing was in the crank, not the flywheel. Been a while since I dropped my tranny...

BAC5.2 · Post by **BAC5.2** » Mon Jan 23, 2006 7:31 pm

As far as hours of shop labor, it's about 5 hours to remove and replace a unit.

It's probably not the pilot bearing. That's not really a load bearing surface, it is simply a way to easily allow the flywheel and the input shaft to rotate at different speeds without much friction. If it were bad, you'd hear it ALL the time and it would increase with pitch as engine RPM increases.

If you hear a grinding, whining noise that goes away with clutch depression, there are a dozen things I could think to be wrong. First gear synchro, input shaft bearings, output shaft bearings.

Without taking it apart, it's difficult to say.

My personal outlook? If it gets worse, worry more about it. Maybe try to line up buying a known-good used tranny, just in case.

What fluid are you using now? That is probably the most important question.

professor · Post by **professor** » Mon Jan 23, 2006 9:44 pm

I've been driving my BMW with the exact same symptoms for 30,000 miles with no further change

I'd drive it unless you just can't stand it. You probably have a worn input shaft bearing on the tranny

general bacardi · Post by **general bacardi** » Wed Jan 25, 2006 7:33 pm

BAC5.2 - Why is fluid the most important question- are these trannies fussy about oil?

I'm using regular (non-synthetic) Valvoline GL-5 gear oil (it's either 75W90 or 80W90, I can't remember right now) - i.e. this stuff:

http://www.valvoline.com/pages/products ... roduct=114

BAC5.2 · Post by **BAC5.2** » Wed Jan 25, 2006 7:38 pm

Sometimes, fluid can cause odd noises. I used some ghetto dino oil for a thousand miles and the tranny made all kinds of funny grinding noises. Switching to different fluid changed that dramatically.

general bacardi · Post by **general bacardi** » Wed Jan 25, 2006 7:42 pm

What brand/weight oil would you recommend?

BAC5.2 · Post by **BAC5.2** » Wed Jan 25, 2006 7:56 pm

3quarts of Redline Lightweight Shockproof
1quart of Motul 75W90

I use 4quarts of LWSP in my Forester, but I'm gonna try to mix it up with the Motul next time I change, just to see.

The Legacy tranny will probably get 4quarts of Motul. Or 3 quarts Motul, 1 of LWSP.

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Bad pilot or input shaft bearing -how long till trans blows?

Bad pilot or input shaft bearing -how long till trans blows?

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