Gearbox? Clutch?

[ghr]

Since the dual mass flywheel broke apart (115 ps so no recall) a few years ago, when accelerating in first and then flooring the clutch to change into second keeping the clutch pedal depressed I noticed a noise something obviously spinning that decreases in frequency as the transmission slows down to a stop still with the clutch pedal depressed. This has now got worse and has become a rumble when in gear, say third, and taking my foot off the accelerator so that the engine and transmission brake the car. Putting my foot on the clutch while doing this and the noise slows in frequency and then diasappears. The car accelerates okay in any gear but once at high revs in any gear there is a rumbling noise.

 

Changing gear is no problem and the clutch works fine. My thoughts are bearing/low oil but would value anyone else's opinion.

 

[Mk2 2002 1.9Tdi 6 speed gearbox]

 

 

Grateful for ideas

[nicebutdim]

Could be the input shaft bearing on the gearbox. When the DMF came apart it could have put undue forces on the bearing and damaged it. Bearings quickly self destruct in short periods of time so be careful if it is the cause. If it is a similar design to the mk1 5 speed box then the bearing is possible to change without box disassembly, but it does mean the box coming out. 

Can't be the release bearing or other clutch components as the noise would be constant with engine noise. 

[ghr]

Appreciate your time and advice. Take your point about the clutch. Bearing makes sense as it is a 'rotational' noise. Once the box is out do I need special tools to get the old bearing out? Dreading removing the box - have new Haynes manual complete with the timeless 'See section 7.9' and there's a section 7.8 but no 7.9.

[BigDog]

Looking at Elsawin it looks like the input shaft has has taper roller bearings which bear on internal races so you would need to split the housing to replace the bearing if knackered.

Call me a stoopid but if it were mine I'd drain the oil, check for anything metalic or broken bits coming out with the oil and if OK then fill up and carry on 'til it stops operating properly or is very obviously in distress.

I'm not entirely sure I understand your description of when the rumble stops. Are you saying the rumble slows in frequency and stops when the car is moving, you press the clutch and a gear is in engagement or when the box is in neutral and the clutch depressed fully? Also are you saying the rumble stops only when the car comes to a stop (if it only happens when a gear is in engagement)? I would not follow your reasoning if the rumble stops during coasting in gear with the clutch down, because the input shaft is surely then rotating at a speed defined by the road speed and the trans. ratio. Do you get the rumble with the box in neutral and the clutch up (although without the bearings under load they may not make the noise anyway)? Could it be the release bearing - if this is partially siezed its face will spin against the clutch spring fingers at a speed that might vary as you describe; long shot though? Let me know if you want gearbox pdfs.

Matt

[ghr]

Thanks for your reply. If coasting and the box is in neutral and clutch not depressed then no noise. Likewise if coasting in gear with the clutch depressed then no noise (noise before depressing clutch though while coasting). Taking foot of accelerator while in gear I get noise but acclerating again noise stops. Coasting at any speed/any gear with the clutch depressed and no noise. I have the drain plug tool coming and hopefully here tomorrow. I'll do what you suggest and drain the oil, check the amount and look for metal bits. If none then I'll refill with new and see what happens.

 

Again, thanks for your help. I'll let you know how it goes on Saturday.

[uk_promonsta]

Any luck? mine also does this and havent managed to pin point it either.

[ghr]

No. The bloody drain plug key hasn't turned up yet. They forgot the order then the bank holiday turned first class post into third class. As soon as I get it I'll let you know.

[ghr]

Still didn't arrive so I went to the local motor factors and got one. Cost a quid more than the internet one. Should've gone there in the first place. All set for tomorrow.

[ghr]

Job done. Just under two litres came out. No metal bits that I could see. The rumbling noise is still there at high revs in any gear. This doesn't build up; it's sudden once get to a certain number revs. I don't usually rev the guts out it anyway so it may have been there a long time. Good news is that all the other noises have stopped. Bad news is that there appears to be an oil leak somewhere. Only a drip leak. Quite a large area around the drain plug is covered in oil and an area on the the plastic tray under the engine. The leak could be the drain plug but I suspect that's wishful thinking. Anyway I've filled it up with new oil (Castrol 75W/90 Universal GL4/GL5 from Halfords £12.99). I used one litre bottles that have a nifty pull out nozzle and the bottle is pliable so you can squeeze the stuff in there. It's quite thick at room temperature so you don't tend to spill any unlike the hot oil that comes out at a rate of knots. You get enough of an angle with the bottle at the right of the filling point. Just need to sort out the leak but I have't a clue where to start. At the moment it drives like it always has done no noise (apart from the one mentioned above) and smooth gear change so I'm inclined towards Matt's suggestion of driving it until it really complains.

 

Many thanks for the time you spent replying and your advice.