[shepherd32]

So I changed the fluid in my 6-speed transaxle and now it has started to sound like a very quiet jet. I thought a pinion bearing would give up before 155,000 miles and why didn't it make noise before the change? It is very quiet, barely audible with the windows up and radio off, but directly related to road speed with no effect on sound with the car in gear or in neutral while moving. Ideas?

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[tamathumper]

Are you the original owner, or is it possible the previous owner had added something to quiet the tranny and you've now changed it out?

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[shepherd32]

I am the third owner, but I've had the car for 80,000 miles and definetly would have noticed this sound before now. A "transmission quiet" fluid would be an awesome product, but if that was the case, then it would operate the same as before the fluid change, just with a touch of noise now - which is way less worrying then "something is now wrong".



What does a 968 tranny with low/no fluid sound like? The transaxle was approprietly warm after an hour drive, not enough to sizzle water tho. Maybe it's leaking very slowly? I'll try to put more fluid into the trans in the morning, see if it's still full.

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[tamathumper]

Aside from the noise, how is it operating differently?

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[flash]

pinion bearing failure has nothing to do with mileage. it can happen at very low or very high mileage. it also has nothing to do with the year of the car. it has only to do with how much preload was installed on the bearing, and since it was mechanically installed, and the case is cast, the tolerances add up in the wrong direction some of the time.



as for the fluid change "causing" the sound, likely it was there, but masked by a thicker fluid. a thicker fluid would coat the walls of the case more, and dampen the sound.

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[shepherd32]

[quote name='tamathumper' timestamp='1341916090' post='129089']

Aside from the noise, how is it operating differently?

[/quote]



It works a lot smoother now. I can still hit all the gears and the synchros seem to be working just fine, but it does shift better/easier now. Overall, I'd say it was working great except for the noise. It sounds like I'm playing Gran Turismo in a car with straight cut diff, but I think I'll start worrying about it if it gets progressivly louder and louder.



I hope that process is a matter of months rather than days, but from reading through other posts, it seems as if it can last a little bit if I can only just barely hear it now.



Thanks for the info Flash, I guess I'm looking at the next tear apart job. At least it's something new this time.

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[flash]

yup - sounds like they put in a heavy fluid, and you replaced it with a lighter one.



just realize that the longer you go with the noise, the higher the likelihood of bits of metal from the degrading bearing getting into places they shouldn't and doing other damage that can significantly raise the prices of the repair.



you can help stave off the damage, and delay the repair a bit, by repeatedly changing your fluid, and thereby getting the damaging bits out of there, but it's only a patch.

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[KRAG50]

Do you still have the old fluid, if so put it into a white bucket, let it set for a couple of days, slowly poor it out. When I did mine this way I did see some minute particles. Now I drain a pint or so every driving season, just to look for issues.

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[RS Barn]

You would be surprized to see how small the pitting in race can be and still make lots of jet noises.

When they really get bad, there is another noise on decel

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[tamathumper]

And strap a big magnet next to the drain plug to catch the steel particles. <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

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