New noise goes away when clutch pedal is depressed

[Terry B.]

Yesterday when I started my 62 340HP I noticed a kind of whirring sound. I thought it was the heater fan and turned the heater knob and the fan came on and I realized the sound was not from the heater fan. I was idling in neutral and when I pressed the clutch to put it into gear the sound went away. Clutch in no sound clutch out I hear the sound. Any ideas as to what this might be?

[Wayne C.]

Re: New noise goes away when clutch pedal is depressed

sounds like a bad throw out bearing to me. wayne

[Thomas P.]

Re: New noise goes away when clutch pedal is depressed

This is highly unusual, but several years ago, I saw a standard transmission Oldsmobile (yes an Oldsmobile with a standard transmission) that had the thrust bearing on the crankshaft worn so badly that pushing the clutch in moved the crankshaft forward and caused noise changes.
You could actually see the crankshaft move.

[Domenic T.]

Re: New noise goes away when clutch pedal is depressed

Terry,
Ajjust your free play on your clutch and check the return spring, you might buy a little more time on the throw out bearing.

DOM

[Bob H.]

Re: New noise goes away when clutch pedal is depressed

Terry:

I agree with Domenic. If that doesn't solve it then a new bearing is about $40. It's not too difficult to change, remove driveshaft, shifter, speedometer cable, rear cross member that supports tranny and bottom bell housing cover. You can unbolt and slide the transmission back far enough balancing the front shaft on the rear edge of the bell housing. You can then remove the old one and install a replacement. You need to be careful that it is installed properly with the fork in the groove. I use a small jack to hold the engine up. A block of wood under the rear of the pan works but I drill a hole in the center for the drain plug to sit in and to make sure it is not supporting the engine.

You may check out the clutch also to make sure it is good condition. The throw out bearing could also have been installed incorrectly. Both the forkand the spring go iin the groove.

Bob

[Richard S.]

Re: New noise goes away when clutch pedal is depressed

sounds like noise i had a couple months ago.pushed in on clutch and screeching noise would disappear. went to all the trouble to replace throwout bearing and noise was still there. started disconnectiong alt. water pump, tensioner etc, noise still the same. ended up finding ballancer was seperating and material that seperates inner and outer pieces of balancer was rubbing very slightly on timing chain cover, but would move forward just enough with clutch pedal pushed to stop the noise. then i replaced ballancer and problem solved.

[Duke W.]

Re: New noise goes away when clutch pedal is depressed

Here's the deal. When the clutch pedal is up, there is no load on the throwout bearing and it's not turning, so it can't make any noise, but the transmission input shaft and counter gear are spinning.

If you push in the clutch, the transmission winds down, so if the noise stops, it's the transmission. A certain amount of transimission noise in neutral is normal in some cars. If it gets worse with time and mileage, it's probably either the front main transmission bearing or the countergear needle bearings.

Make a note of it and see if it increases with miles. If it is a transmission bearing, it will get noticeably louder. If it stays the same, it's normal.

Duke

[Terry B.]

Re: New noise goes away when clutch pedal is depressed

Thanks for the input so far. Here is a little more information. It looks like the clutch was replaced/rebuilt in April of last year (work request shows Clutch assm $189 and resurface flywheel $36). I'm not sure what the mileage was then but I've added nearly 2,000 since purchase just before Thanksgiving. Also, the gear shift chatters a lot at between 55 and 60 mph (and I'm pretty sure at similar rpm in lower gears). I think something is out of balance.

[Stephen L.]

Re: New noise goes away when clutch pedal is depressed

If you place the car in gear and noise ceases then the transmission is the culprit. When in gear and clutch depressed the transmission shafts are not turning. If the noise persists under these conditions then the pilot bearing would be suspect as the transmission is not turning but the crankshaft is.

[Domenic T.]

Re: New noise goes away when clutch pedal is depressed

Duke,
That is a possibility alright but I have seen many T/O bearings dry up and not turn rubbing the fingers on the pressure plate.
Then when pressure was applied the balls would break loose and the T/O bearing face would turn with the fingers stopping the noise.
This situation would also get worse and make more noise the more it were driven.
Clutch pedal adjustments are commonly ignored and as you know and when the disc wears the adjustment changes.

DOM

[John G.]

Re: New noise goes away when clutch pedal is depressed

Does the noise go away when it warms up? If it's been sitting awhile or it's cold, it takes a bit to lube the gears/bearings.

John G

[Bob H.]

Re: New noise goes away when clutch pedal is depressed

Terry

I just replaced my TO bearing that had the same symtoms you have. It was worn out. When removed, I could spin it and it was very rough to turn and would bind up. Applying forward pressure on it, such when depressing the pedal; it was smooth with no noise.

Your rattling shifter could be no anti-rattle spring or a weak spring on the shifter. Cheap simple fix if you can get under the car.

[Domenic T.]

Re: New noise goes away when clutch pedal is depressed

Terry,
Start your car and push your clutch pedal in slowly and see if the noise go's away before you release the gears.
If not then it's the trans, if it changes with little pressure on the pedal then you have solved the mystery, it's the T/O bearing.

DOM

[Chuck S.]

Re: New noise goes away when clutch pedal is depressed

...if it changes with little pressure on the pedal then you have solved the mystery, it's the T/O bearing...

I agree.

Proper clutch free play adjustment can be taken for granted; it doesn't seem important when a new clutch is first installed and may be overlooked by the tech. BUT...if your new clutch installation doesn't include proper free play adjustment, the throw out bearing can run continuously until it begins making that rustling, whirring noise you're hearing. Light pressure on the clutch pedal just begins to load the bearing making the noise disappear.

Throw out bearings are not designed to run continously. I once had four throw out bearing replaced under warranty before I got tired of spending time at the dealership, read the **** service manual and adjusted the clutch free play myself. End of problem.

[Earl S.]

Re: New noise goes away when clutch pedal is depressed

Here's the deal. When the clutch pedal is up, there is no load on the throwout bearing and it's not turning, so it can't make any noise, but the transmission input shaft and counter gear are spinning.

If you push in the clutch, the transmission winds down, so if the noise stops, it's the transmission. A certain amount of transimission noise in neutral is normal in some cars. If it gets worse with time and mileage, it's probably either the front main transmission bearing or the countergear needle bearings.

Make a note of it and see if it increases with miles. If it is a transmission bearing, it will get noticeably louder. If it stays the same, it's normal.

Duke

Duke is right on the money here. I just went through this myself after a fresh rebuild. Slight chance it could be the pilot bearing but more than likey the input shaft bearing is going bad. It could just as easily be a gear as well. That was my problem, the new 3rd gear I put in was a bad part...

~m