Knocking noise from transmission at idle

[Lucas03es]

So this just started, my Galant has a knocking noise coming from the transmission when I am idling. It isn't super loud, but i is noticeable, and is not right. When I push in the clutch, the noise does seem to go away completely, also when I rev the motor it does (or maybe it drowns out the sound?). I just recently replaced the transmission fluid with Pennzoil syncromesh (400 mi ago), and adjusted the clutch at the same time. Could it be the clutch adjusted improperly and it is not completely disengaging? Thanks!

 

[brandon1239]

more than likely its your throwout bearing.

 

[Silent_White]

chipped tooth.. even with the car in neutral you have moving gears in the tranny until you push in the clutch. whatever chipped off could be floating around your tranny causing damage to the rest of the assembly. what did the fluid look like when you changed it? was it heavily metallic?

I drain a little right now to look at it. you might be looking at a rebuild...

 

[talondave]

Sound like the through-out bearing! But very well could be something in your tranny.

 

[Lucas03es]

So I cleaned out my oil drain pan to where there was no oil residue left so when I drained the fluid out. I crawled under the car with my 15/16" socket and breaker bar, broke it loose(it was tight), and nothing. I mean nothing as in no fluid came out. There was only a bit of brown goo on the drain plug. Where could it leak from? Could it be making that noise because there is no fluid in it? Have I ruined my tranny? 15 miles driven on it like this tops no boosting limping it home.

 

[luv2rallye]

Manual trannys are extremely strong (and all gears are always engaged with each other). 15 miles with no oil where it once had oil is not likely to ruin it. Most tranny leaks are from worn driveshaft (halfshaft) seals. You will have to figure out the leak but the knock sounds like throwout bearing to me by the way you describe its behavior with clutch pedal.

 

[rlacasse1]

Sounds like throw out bearing to me as well.

As for the tranny, if you didn't drive the shit out of it for those 15 miles then you are probably ok.

 

[92 GSR-4]

My tranny made a knocking-like noise one time. It turned out to be the ACT clutch disc (newer version supposedly) had completely come apart, meaning the inner hub's rivets were loose and coming apart from the outside piece.

Have you done any really high RPM shifts/accidently down-shift instead of up-shifting?

Either way, it sounds like you are going to be checking in the right area (TOB/Clutch)

 

[Lucas03es]

Well I stuck my pinky up into the drain hole, and I got some piece of metal on my finger. I think I might just call it dead and replace the tranny, I don't want a ticking time bomb under my hood. Thanks guys for the help!

 

[GsXdSmKingGsX]

That might be your throwout or release bearing. I have one sitting around if you need it.

 

[Lucas03es]

I am going to drop the transmission here in the next couple days, I'll let you know, thanks.

 

[anteversion]

In my opinion, this is NOT your TOB. A throw out bearing will in fact make more noise when the clutch is pressed in. And it will be more like a grinding or high pitch squealing noise than a ratteling or knocking sound. A knocking sound coming from a tranny is generally generated by a bearing located at the end of one of the shafts.

If the noise is stopping when you press the clutch in, this is because the tranny become un-engaged and all the shafts inside stop rolling on themsleves.

Put some oil in the tranny before you drop this thing to the ground. I bet your problem is caused by a lack of lubrification.

Of course, if you have found some metal chirps in the drain plug hole, it is your choice to drop it or not. But i will try oil first and road test it to check how it will perform.

And there's are for places wich a tranny can possibly leak: the two side axles seals,
the transfer case output shaft seal, or the input shaft seal . If the bellhousing is not full of oil and the clutch is dry, this seal is not leaking.

 

[brandon1239]

in all my experiences the throwout bearing rattles until you push the clutch in, if it gets louder when you push the pedal in you have serious problems.

 

[92 GSR-4]

In light of you finding metal inside the tranny (and the tranny being out of oil also) and also that putting load on the TOB WOULD make the noise louder, I think the tranny needs to come out now. Sure, you can road test it with new oil, but damage has obviously already been done and from here on out its only going to get worse. Just like finding metal in your motor, if you catch it early you will damage less and spend less repairing it. Transmissions are the same way, especially if you send it to a shop like TRE or Shep. They will charge you for any parts they intended to reuse, but had to replace. Right now its wise to not drive it any further and have the tranny sent off for rebuild.

 

[anteversion]

in all my experiences the throwout bearing rattles until you push the clutch in, if it gets louder when you push the pedal in you have serious problems.

How does a TOB should rattle until you push the clutch in?? If well installed and greased sleeve a TOB cannot rattle cause it have absolutely no contact with nothing in movement except while you start pushing the clutch.

And logically, if a bearing is shot and you apply pressure on it, it WILL make more noise. So same thing apply to a throw out bearing