Gearbox grinding noise

Hello

Couple months ago my Peugeot started making “grinding” noise from the gearbox, the noise gets louder and more high pitched when accelerating but it can also be heard when in neutral, when i press the clutch pedal the sound disappears. Both diff bearings and 1of the input shaft bearings were replaced the clutch was replaced as well including the release bearing. But sadly after the first couple of kilometers i started hearing the sound again at first it wasn’t so loud but after around 50 kilometers it was loud as before, any idea what could the problem be ? I am suspecting the other input shaft bearing that wasn’t replaced but the mechanic that checked them before replacing them told me the other bearing was fine.

This is the sound while driving - 374.2 KB file on MEGA

This is with my phone under the gearbox while pressing and releasing the clutch pedal - 1.44 MB file on MEGA

Thanks.

When you press on the clutch pedal, that puts some extra force on the release bearing and the pilot bearing. When the clutch pedal is pressed the trans input shaft isn’t doing much. Was the pilot bearing replaced? My guess the problem is one of those first two, the trans input shaft bearing is possible, but seems less likely. Technical problems prevent my listening to the auto files.

Another weird possibility, when you press on the clutch pedal it pushes on the crankshaft. So there’s some possibility of a crankshaft bearing, maybe a crankshaft thrust bearing.

the mechanic who did not fix it right the first time,

Hey thanks for the response, but i think you misunderstood me. The noise can be heard only when the clutch is engaged, when i press on the clutch pedal the noise stops. The release bearing was replaced but the pilot bearing was not.

Yes, I understand the noise goes away when you press on the clutch pedal. If there’s some play in a bearing, putting force on it will sometimes make the noise go away.

Oh ok i guess i was the one that didn’t understand you :smiley: Would you be able to listen to the audio files when you fix your technical problems ?

If you hear a growl or grind , the transmission input shaft has a bad bearing. Check the clutch release bearings. If you notice chirping noises , push the pedal in with the vehicle still in neutral. If the noises go away when you load the pedal, the problem is with the clutch fork and pivot stud.

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No. But other folks here are probably able to listen and provide a comment. In my experience listening to audio folks post here is rarely diagnostic. You really need to be listening when standing next to the vehicle for audio to be of much help.

Then it’s not the pilot bearing.

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I think it is cool we’ve had 2 Peugout posts in about 2 days! Since most of the forum regulars are from the USA, we don’t see French cars much. They are not sold here.

That said, sounds like a countershaft bearing in the transmission is bad. The bottom line is the mechanic had your transmission out and apart and did not replace every bearing. If the diff bearings and one input shaft bearing were bad, you can assume others in the transmission were not far behind.

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The 3rd gear synchro starting to crunch on my 4yr old 30k Mitsubishi. We had a warranty but I expected better quality. I don’t recall even looking at a Honda/Toyota.

Thanks to everyone for the help, i have one last question. Let’s say i am going down hill in 4 gear while pressing the clutch will the input shaft still be spinning (getting turn by the output shaft) ?

Hi Jackie:
Yes, the transmission input shaft will be turning because you have it in gear (4th in this case).

If you slip the transmission into neutral and then depressed the clutch, the input shaft will not be turning.

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hmm thanks but that means there is a chance that the noise is not from the input shaft because when i am going downhill in gear with pressed clutch the noise stops, i can hear something speeding up and making the grinding noise while i slowly release the clutch pedal

Does this noise happen when:

  1. You slowly release the clutch while in 4th gear when going down a hill?
  2. Or when you release the clutch to accelerate from a dead stop, like from a stop sign?
  3. Or when you are stopped in neutral with your clutch pedal depressed and you slowly release the clutch then.

Which of the above conditions do you hear the noise?

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The noise can be heard all the time when the clutch is released it doesn’t matter in what gear or if i am going down a hill or sitting in one place in neutral, but it gets a lot louder when accelerating. For the reply above i meant the 1 condition. Since the input shaft should be spinning when going down hill in gear while pressing the clutch pedal but the noise can’t be heard during this condition, i can hear it only after i release the clutch this leads to believe the problem is from something else.

I am going to guess either synchro’s throw out bearing clutch release fork pivot ball fork itself or a combination of all the above a good mechanic should be able to figure it out easy enough.

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Based on your description, it sounds like it’s either the clutch release bearing, or a bearing inside the transmission (or something similar inside the transmission).

Based on your initial post where you said you had the clutch release bearing and the transmission input shaft bearing replaced which fixed the noise for about 50 kilometers, I would start with an inspection of those two. The parts could have been faulty or incorrectly installed. If they look fine, then to look elsewhere inside the transmission.

The input shaft is spinning when the clutch is out and you’re in neutral. One end of that shaft is the input shaft bearing. The other end usually has a needle bearing. That should be inspected as well.

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It sounds like the transmission is going to have to come out in any event. Might as well bite the bullet, pull the trans, and then the shop should be able to determine what the problem is. Or is there a reason you’d like to know before removing the transmission?; i.e. warranty issue or something?