Release bearing - risks

[944_85]

The other day I noted after pulling the car out of the garage that there is a sort of knocking sound coming from the back of the car at the gearbox area. This is when car is standing and idling in neutral. Reading the Haynes guide, they indicate that this is a damaged release bearing. Does this sound like a correct diagnose?

If yes, what is the risk, if any, using this car like this? Can it damage something else like the gearbox?

I am already saving for a clutch replacement, as the rubber center is on it's way out. Just trying to judge what else needs to be done and how urgent.

 

[Mike_Pollock]

Release bearing is on the clutch which is at the front, so sounds wrong diagnosis, but sounds do "travel" around cars.
Does it make the sound with the clutch pushed in, in or out of gear?
There are so many things it could be!
Mike

 

[944_85]

With clutch pedal out = noise
With clutch pedal pushed in = no noise

 

[JM1962]

With the clutch pedal out the input shaft of the gearbox will be turning at engine speed, with the pedal in it won't be. Get someone to operate the pedal and have a listen underneath, just make sure they don't run you over []

 

[DivineE]

ORIGINAL: JM1962

With the clutch pedal out the input shaft of the gearbox will be turning at engine speed, with the pedal in it won't be. Get someone to operate the pedal and have a listen underneath, just meke sure they don't run you over []

Well you know simple as it sounds I never would have thought of that, he had me puzzled there. Release bearing is usually the opposite:

Clutch in = noise (from front of car)
Clutch out = no noise

 

[bertelli_1]

It could also be a torque tube bearing.

 

[Mike_Pollock]

If its from the rear - torque tube bearing. if its from the front Clutch release.
Mike

 

[944_85]

Well, took it for a spin a hour ago, and closely listed again.

Unless the "knocking" sound which I am hearing is being relayed from somewhere else, it sounds like it is definetely coming from the gearbox area.
Checked again : clutch pedal pushed in = no noise, clutch pedal out with car in neutral idling = noise.

I presume then it must be the tube bearing. Then my question again: any risk driving around like this? Could the bearing totally get stuck and made the engine "jump" out the car?

 

[Mike_Pollock]

Worst case would say is broken shaft, what that could do - I dont know.
Could be gearbox layshaft - have you checked state of gearbox oil / level etc?
Mike

 

[Diver944]

To some extent they all rattle under the conditions you describe, both of mine do it and have done for the past 12 years.

Do you know any other 944's nearby that you can listen to? Unless its a major clunking it sounds normal to me

 

[Frenchy]

What Tony said but mine goes silent when warm ?

 

[zcacogp]

As Paul said - these cars often have a lot of transmission noise, and it's nothing to worry about. Check with others to see how 'normal' yours is.

If it is a torque tube bearing then I'd imagine it could get frighteningly grumbly before it will cause any other damage. As in, very very noisy indeed. Worst that is likely to happen is that the torque tube and housing are damaged, but I suspect you may just replace the whole lot with a known-good second hand assembly anyway.


Oli.

 

[Mike_Pollock]

I'm in Leicester and your welcome to come for a drive, second opinion etc and I'm sure there are others around who would do the same - whereabouts are you?
Mike

 

[944_85]

I am actually from across the water, in Belgium. Still possible to drive past for a listen to Leicester but a slightly long drive []

When cold the noise is worse than when the cars is warm. When I just pull it out of the garage, it is a clear clunking noise, after a short drive it is much quieter. I will try an get a listen from another 944. Maybe it is normal, however I do have a slight noise like a wheel bearings on it's way out, when I am at speed. This could be a wheel bearing, or the tube.

Gearbox oil is not the issue, as it was on mineral oil which has now been changed to full synthetic. Shifts extremely smooth.

 

[Mike_Pollock]

Yes, would be a long trip!

The only things moving at the rear when idling in neutral are the prop shaft and the gearbox layshaft, both of which stop when the clutch pedal is depressed.

You say gearbox oil recently changed, how much did you put in? Capacity is often quoted as 2.0Litre - mine took approx 2.6! That would account for it quitening after a short run.

Not sure what else to suggest!

Mike

 

[944_85]

Bought 3 liters of oil, and it also took around 2,6 liters. Pretty sure oil is not the issue here.

I will continue to use as is, until I get the clutch replacement done, which is planned for the winter. When everything is a part, it would be a good time to search for the "guilty party"

Thanks for the help!