Technical 🆘Manual transmission problems (LOUD NOISE)

[DragonHeart6]

Fiat Bravo T-Jet six-speed manual transmission:
The other day, while driving slowly, I started hearing a slight noise coming from the gear shift area.
I thought it was insufficient lubrication, since I had previously repaired a leak, which I eventually fixed. (I was away from home for work.)
To get home, I tried adding a liter of oil. The noise seemed to have gone away, so I drove home(60 kilometers)
I parked near a store to get a cardboard box to put under the car to check for leaks overnight.
I drove back home (near the store).
I parked the car in neutral to place the cardboard box under it, and that loud noise began(video attached)
In the morning, there wasn't a drop of oil on the ground, and the loud noise was still there.
I drove to the mechanic (3 minutes away), and the loud noise was goneHowever, there is indeed a slight noise, probably coming from the primary driveshaft "also according to the mechanic".
I wanted to have the oil level checked, but the mechanic refused, saying he didn't have time. So I took the car to work, waiting to find another manual transmission to replace. The mechanics will be closed for two days now, but I need the car for work.
My fear now is that the oil level is too high or too low. What do you think could have happened? What can I do?
The clutch and flywheel are new, replaced a few months ago

Please help

 

[bugsymike]

Fiat Bravo T-Jet six-speed manual transmission:
The other day, while driving slowly, I started hearing a slight noise coming from the gear shift area.
I thought it was insufficient lubrication, since I had previously repaired a leak, which I eventually fixed. (I was away from home for work.)
To get home, I tried adding a liter of oil. The noise seemed to have gone away, so I drove home(60 kilometers)
I parked near a store to get a cardboard box to put under the car to check for leaks overnight.
I drove back home (near the store).
I parked the car in neutral to place the cardboard box under it, and that loud noise began(video attached)
In the morning, there wasn't a drop of oil on the ground, and the loud noise was still there.
I drove to the mechanic (3 minutes away), and the loud noise was goneHowever, there is indeed a slight noise, probably coming from the primary driveshaft "also according to the mechanic".
I wanted to have the oil level checked, but the mechanic refused, saying he didn't have time. So I took the car to work, waiting to find another manual transmission to replace. The mechanics will be closed for two days now, but I need the car for work.
My fear now is that the oil level is too high or too low. What do you think could have happened? What can I do?
The clutch and flywheel are new, replaced a few months ago

Please help

I would check oil level to start with.
Too high will just cause oil leaks, but too low is bad for bearings etc.
First video sounds like an exhaust manifold gasket blowing to me.

 

[xarenwo]

That sounds like a flywheel noise, it's a very sharp knock. It's like a big mass is hitting something and resonates. Did you ever touch the flywheel guards ? The 2 black metal guards between engine block and gearbox ? If those are bent, the flywheel can touch them. It's weird it makes noise only when you release the clutch though, sounds like there is something metallic that is loose, the insides of a gearbox would make a whining noise, if there would be such a problem to make such a big knock, the whole gearbox would disintegrate, there are only the gears , synchros and the differential that are moving, but they have small teeth and they would grind, not knock. Also the sound sounds the same frequency as the engine is turning, the shafts and gears inside the gearbox have different speeds based on their ratio.
The thing is that there is also a delay from when you press the pedal to when the noise stops, which indicates it's a bearing or something that stops spinning when you press the clutch, and that does lead to the gearbox, but it also might be something on the clutch disc rattling around the pressure plate. It can be that the part with the splines of the disc is damaged and the disc does not rotate normally. Does the car drive ok, does the clutch slip ?

Too much oil would just be thrown out from the breather on top, and it would make engaging gears harder because the synchronizers wouldn't work properly, but it should not cause any noise or permanent damage.
You can't really check the oil level on an m32 gearbox. Gen1 had a plug but it's kind of useless and Gen2 does not have it. Only way is to take the oil out and measure how much you got out, keeping in mind around 200gr are always left in the gearbox while it's on the car.

If your gearbox bearing would be bad, you would have whining while in gear, gear level would move and wanting to get out of gear, and if it's so bad that the shafts are leaning onto each other and grinding the gears, then you would have known in advance and wouldn't just start randomly.

Anyways those are just my opinions, there are many things that can cause that noise, but I'm pretty sure that if it would be some piece of metal inside the gearbox rattling around and making such noises, the gears would already disintegrate because it sounds like a big piece of metal that would not get picked up by the magnets in the differential housing.

If you can safely lift the car and support it with jackstands (always), it's not that hard to remove the gearbox oil and check how much you have. You can recycle it if clutch was changed recently and put it back without changing it. You just need to remove that metal bar with 4 m16 head bolts so it doesn't splash around everywhere, and undo the plug. When you put the plug back you should use some sealant. Given you are in Italy , you can use Sigill Block, red container, you can find it in ferramenta, just go around the bolt on the thread with 1 line, no need to put too much. This seals the bolt but does not block it unlike thread locker.
Then filling it back up, from the top is not that hard. Torques for bottom bolt near the differential are 15-17nm and top filling plug 25nm.

 

[xarenwo]

I would check oil level to start with.
Too high will just cause oil leaks, but too low is bad for bearings etc.
First video sounds like an exhaust manifold gasket blowing to me.

Hi again Mike, it does also sound like an exhaust manifold gasket, but If I understood right, the noise comes only when he releases the clutch and it's engaging, thus turning the gearbox primary shaft and clutch disk. Besides other things I listed (in my opinion as always), it could also be that the pressure plate's teeth became bent and when the pedal is pressed the CSC presses them evenly but when releasing the CSC, it still touches those teeth/wings but 1 or 2 stay more outwards and they are hitting the bearing. Just a theory. But this would cause jerking while driving because the clutch would have gripped randomly and not evenly.
On second thought, if the bearing behind the CSC is bad, that would cause a lot of play on the primary shaft of the gearbox when engaged and vibration, so the disc would just rattle and hit around. Wasn't the play of primary shaft checked when the clutch was changed ? That should always be done when the gearbox is off.

 

[DragonHeart6]

That sounds like a flywheel noise, it's a very sharp knock. It's like a big mass is hitting something and resonates. Did you ever touch the flywheel guards ? The 2 black metal guards between engine block and gearbox ? If those are bent, the flywheel can touch them. It's weird it makes noise only when you release the clutch though, sounds like there is something metallic that is loose, the insides of a gearbox would make a whining noise, if there would be such a problem to make such a big knock, the whole gearbox would disintegrate, there are only the gears , synchros and the differential that are moving, but they have small teeth and they would grind, not knock. Also the sound sounds the same frequency as the engine is turning, the shafts and gears inside the gearbox have different speeds based on their ratio.
The thing is that there is also a delay from when you press the pedal to when the noise stops, which indicates it's a bearing or something that stops spinning when you press the clutch, and that does lead to the gearbox, but it also might be something on the clutch disc rattling around the pressure plate. It can be that the part with the splines of the disc is damaged and the disc does not rotate normally. Does the car drive ok, does the clutch slip ?

Too much oil would just be thrown out from the breather on top, and it would make engaging gears harder because the synchronizers wouldn't work properly, but it should not cause any noise or permanent damage.
You can't really check the oil level on an m32 gearbox. Gen1 had a plug but it's kind of useless and Gen2 does not have it. Only way is to take the oil out and measure how much you got out, keeping in mind around 200gr are always left in the gearbox while it's on the car.

If your gearbox bearing would be bad, you would have whining while in gear, gear level would move and wanting to get out of gear, and if it's so bad that the shafts are leaning onto each other and grinding the gears, then you would have known in advance and wouldn't just start randomly.

Anyways those are just my opinions, there are many things that can cause that noise, but I'm pretty sure that if it would be some piece of metal inside the gearbox rattling around and making such noises, the gears would already disintegrate because it sounds like a big piece of metal that would not get picked up by the magnets in the differential housing.

If you can safely lift the car and support it with jackstands (always), it's not that hard to remove the gearbox oil and check how much you have. You can recycle it if clutch was changed recently and put it back without changing it. You just need to remove that metal bar with 4 m16 head bolts so it doesn't splash around everywhere, and undo the plug. When you put the plug back you should use some sealant. Given you are in Italy , you can use Sigill Block, red container, you can find it in ferramenta, just go around the bolt on the thread with 1 line, no need to put too much. This seals the bolt but does not block it unlike thread locker.
Then filling it back up, from the top is not that hard. Torques for bottom bolt near the differential are 15-17nm and top filling plug 25nm.

Thanks, you've been very precise and detailed.
However, I already knew I had a worn gearbox: the gears were having a bit of trouble shifting. Furthermore, a couple of times recently, fifth gear seemed to get stuck inside (always during a downshift).
The strange thing about all this is that the loud noise in the video has disappeared

 

[bugsymike]

Interesting to hear what you find.

 

[DragonHeart6]

Interesting to hear what you find.

I'm already looking for a new transmission. The problem is that there are several versions for sale, similar ones I believe, with different part numbers. All produced by Fiat: Bravo, Delta, Giuletta, Mito.
But the codes on eper are different. Do you know if they are all interchangeable (plug and play) or if something changes in the gears?
I'm looking for manuals but I can't find these details

 

[bugsymike]

I'm already looking for a new transmission. The problem is that there are several versions for sale, similar ones I believe, with different part numbers. All produced by Fiat: Bravo, Delta, Giuletta, Mito.
But the codes on eper are different. Do you know if they are all interchangeable (plug and play) or if something changes in the gears?
I'm looking for manuals but I can't find these details

Sorry I don't have any details on model specifics.

 

[Sylvester22]

How many miles/km does your car have?
Perhaps they fix wasn't done properly either.