Confusing sound from gearbox-Any ideas please?

adamskibx · Post by **adamskibx** » 08 Jul 2005, 01:55

Basically, my BX is going very well and everything works 100% but there is a worrying sound from the gearbox that I want to put right, no matter what it takes effort wise.
The symptom is this- Its a wooshing/grinding type sound as far as I can make out that occurs for a certain number of degrees when something in the gearbox rotates, and it is most noticable in first and second gears, particularly when decelerating or not under load from forward acceleration. I think the only reason I dont notice it as much in the other gears is because its something to do with engine speed rather that driveshaft speed- This becomes obvious when you are going along and then depress the clutch and rev the engine a bit. Strangely, the same sound cannot be heard when the car is stationary and you select a gear and rev the engine with clutch pressed. Its obviously the engine speed dependant bits of the gearbox as the frequency of wooshing increases as the revs increase, and yet, for some reason I cant replicate it when the car is not moving. It makes no sense to me so I was hoping someone with a more in depth knowedge of gearboxes might be able to diagnose the problem from this description:-) Its probably a bit hard without hearing it but ive done the best I can- Only reason its started to worry me is because it got worse after a trip to North-West Wales yesterday.
Cheers, Adam

bernie · Post by **bernie** » 08 Jul 2005, 02:15

Hi Adam
When you did the CV joint gaiter did you replace the gearbox oil that came out with the drive shaft removed

fastandfurryous · Post by **fastandfurryous** » 08 Jul 2005, 02:27

Are you saying that when driving along you can dip the clutch, rev the engine and it makes the noise? If so, does it have to be in gear to do this, or will it make the noise in neutral too?
The wooshing/grinding noise is almost without doubt a bearing breaking up. I'm wondering if it might actually be something on the engine rather than the gearbox, or possibly the clutch release bearing. I have a drivebelt tensioner roller bearing breaking up on my 1.9TD engine at the moment, and it makes a similar-ish noises to what you're describing.
If you dip and raise the clutch with the engine idling, do you get any difference in noise at all? The input shaft bearings on BE gearboxes can suffer from under/over full oil levels, and are often noisy (but last for ever even when noisy)

Post by **Peter.N.** » 08 Jul 2005, 02:29

Yes, first check the oil level. If the noise only occurs when moving the problem must occuring when the gearbox is under load if it is varying with engine speed rather than road speed it will probably be a layshaft bearing or possibly the first motion shaft bearing. If its varying with road speed it could be a wheel bearing, they sometimes only make a noise when under load.

adamskibx · Post by **adamskibx** » 08 Jul 2005, 02:30

Yes Bernie I made sure it was topped up as it should be. It was making the sound before this too on the brief drives I made in it to MOT center etc but didnt really worry me as it never got any worse but it has done after a 400 mile trip yesterday so im inclined to put it right. Its not annoying as such but it is annoying in that its a bit of a worry and the car would be A1 if this problem didnt exist. I expect something is very worn as the gearbox is the one part of the car that will have gone for 160,000 without an overhaul.
Regards Adam

fastandfurryous · Post by **fastandfurryous** » 08 Jul 2005, 02:36

If it refuses to shut up, and is definitely a gearbox bearing, drop the oil out and refill with EP90. It's thicker than the recommended oil, and has EP additives (obviously!) Peugeot don't recommend it, but I've run EP90 in a noisy BE gearbox before for tens of thousands of miles, and it worked a treat.
Makes the gearchange a bit stiff first thing in the morning in the winter, but it's not that bad, and easily liveable with.

adamskibx · Post by **adamskibx** » 08 Jul 2005, 02:38

Sorry guys you wrote that in the time I was replying to Bernie.
"Are you saying that when driving along you can dip the clutch, rev the engine and it makes the noise? If so, does it have to be in gear to do this, or will it make the noise in neutral too?"
Basically yes it makes the sound when coasting, when you dip the clutch and rev the engine (sound increases in speed when you rev the engine), but however it wont do the same when in neutral or when stopped and in gear with cluth pressed.
"If you dip and raise the clutch with the engine idling, do you get any difference in noise at all? The input shaft bearings on BE gearboxes can suffer from under/over full oil levels, and are often noisy (but last for ever even when noisy)"
Yes sometimes you can hear a very faint metalic sound that just sounds like dry bearings spinning- I had this on my Dyane and it went on for 40,000 miles like that until other problems stopped me using it.
"If its varying with road speed it could be a wheel bearing, they sometimes only make a noise when under load".
Umm I wish it was but it definately engine speed dependant and comes from the middle of the engine bay area from what I can make out.
Cheers, Adam

adamskibx · Post by **adamskibx** » 08 Jul 2005, 02:55

"If it refuses to shut up, and is definitely a gearbox bearing, drop the oil out and refill with EP90. It's thicker than the recommended oil, and has EP additives (obviously!) Peugeot don't recommend it, but I've run EP90 in a noisy BE gearbox before for tens of thousands of miles, and it worked a treat".
Umm I might give it a go if its going to be really hard work replacing gearbox parts etc. Be nice to cure the problem rather than the symptom though. I might do this until I can find a second hand gearbox or until I know exactly what to replace. Ive repalaced cogs and bearings in a 2CV gearbox before but I suppose the BX is a rather bigger kettle of fish:-) Regards, Adam