Another weird noise

[Rod_4x4]

Hey, Ive searched and cannot find a descripion of a sound like this. It's a whirring noise that kind of sounds like plastic cogs spinning together, it comes from beind the dash or pto handle from what I can tell. When I push the clutch it it stops, it also happens in neutral as well, and again when I press the clutch in it stops. The sound in quite loud in the cab. Its in a lwb GQ, 1990 TD42 manual with a safari turbo. I'm not very mechanically minded so any info will help. Thanks in advance,
-Rod

[toughnut]

Sounds like the thrust bearing in the clutch.

[Rod_4x4]

Thats one of the things I thought it might be after reading some other posts that were simlar. Is there anyway of defiantly knowing, also is it a big/expensive job? thanks
-Rod

[toughnut]

The bearing itself isn't expensive, BUT. It sits over the input shaft to the gearbox so you have to remove the box to remove the bearing. When you have the box out you may also find that the clutch is either stuffed or almost stuffed depending on how old it is. If the clucth is more than 18 months old its probably worth replacing the whole clutch for peace of mind if nothing else. If your a bit strapped for cash you can just remove the gearbox and replace just the bearing that you can buy from most bearing places or from anywhere that sells clutches. Other than removing the box I don't know how to check the bearing, but with the noise going away when you press the clutch pedal its either the thrust bearing or the clutch itself.

[Slug]

Try clutching it with the car in neutral ... If the noise changes in intensity/ type then its likely a throwout bearing. Like the man said.... not expensive but a right royal arse pain

[Hoonz]

i have a whrrrrring noise under my bonnet too its weird as well

[toughnut]

I think its the weird power steering pump you have on it

[Rod_4x4]

hehe, thank for the advice all, yer when in neutral it makes the sound then when I press the clutch in the noise goes away. And 'whirrrring' was the only way I could describe it, hehe. Oh well it might be a pain in the arse but not as much as the noise itself
Cheers,
-Rod

[toughnut]

Try to find somewhere that will supply you with a clutch you can hand back if you don't need it. Its better to have one on standby if you're pulling the gearbox out and find the clutch is stuffed as well.

[DieselBoy]

Is it auto or manual??

Read the post again carefully guys

He says the noise stops when he engauges the clutch (pedal depressed)
When he dissengages the clutch(pedal returned) the noise is present.

Now thats not going to be the throw out or thrust bearing is it.

That bearing is going to make noise with the clutch engaged, when it is loaded up, pressing on the springs of the pressure plate.

When the pedal is returned to the top, the clutch is dissegaged and the throw or thrust bearing is doing nothing. No spinning, no load, nothing. So how can it be making a noise??

What you are hearing are the gearbox bearings on the main shaft rumbling.
They all do it to a certain extent, if its bad, try running a heavier oil and an oil stabiliser in the gear box.

At the end of the day, ignor it untill the box starts wineing while driving along the road, which will happen adventually, in 1st, 2nd, 3rd and probably 5th. Then wip the box out and get it recond.
Do it as soon as it starts wineing, as if somthing lets go andit lunches it's self, your in for more than a simple bearing replacement job!!!
Pete.

[Slug]

Hmmm
To the best of my knowledge the throwout bearing always had some contact with the pressure plate and spun more or less constantly hence the noise.... Then when they were loaded up with the clutch in they stopped spinning and acted more or less merely as a large surface area to push the fingers on the pressure plate

Could be horribly wrong though !

[DieselBoy]

Nope, that would defeat the purpose of it being a bearing wouldn't it.

The bearing is clear of the pressure plate, it is pulled back out of the way by the carrier that is attached to the clutch fork.
Can you picture the pressure plate doing 3000rpm, then you putting your foot on the clutch, and thrust bearing acting as a solid block??
Arrg, the noise, the shards or metal............. It doesn't bear think about!!!

No, one surface of the thrust bearing makes contact with the springs on the pressure plate, alowing pressure to be applyed the to springs, but also allowing the pressure plate, fly wheel, crank shaft and whole bloody engine to continue to rotate freely.

Cheers,
Pete.

[Slug]

That sounds reasonable ...
Would be dumb to have the bearing stop dead and kinda noisy to boot

Based on a few Google searches, what I said hold's true in that throwout bearing noise will change or stop when the clutch is depressed...
Ie: bearing under load and increase when the clutch is let out.

[DieselBoy]

Seriously, to isolate transmission noise in nuetral, you depress the clutch while the engine is running and engage any gear.
If the noise ceases, it indicates that the noise is in the transmission, caused by such things as lack of lubricant, worn input shaft bearings, chipped gears, worn couter shaft bearings
etc.

If the noise occurs when you depress the clutch pedal, it is the release bearing, broken pressure plate springs, worn spigot bearing etc.

He clearly says the noise stops when he depresses the clutch, so there for the noise is clearly in the transmission.

[Rod_4x4]

Thanks guys, hmmm, it doesnt sound that great.... Pete you sound spot on with what you've said, it has started making noise in 1st, 2nd and I think 3rd, while driving and neutral, all when the clutch pedal is dissengaged, that is I'm not touching the pedal at all. So this is bad by the sounds of it. What am I looking at now? Does it mean something in the gearbox is defiantly stuffed or can I try a different oil or is it to late?

[toughnut]

The throw out / thrust / clutch bearing is in constant contact with the pressure plate of the clutch. When the bearing starts to wear out it vibrates when there isn't as much load on it. ie. when the clutch is disengaged. When you engage the clutch it puts more pressure on the bearing and forces the centre of the bearing to push agains the rear edge of the bearing housing which slows down or stops the vibration effectively silencing the bearing. When the pressure is released the bearing vibrates in the housing again. As I said have a clutch handy when you go to replace the bearing. At least then you can change it at the same time if there is more of a problem.

[DieselBoy]

*Shrugs*

Rod_4X4:
Yeah, if its makiing noises in those gears, your are in for a new set of gear box bearings in the very near future.
Try running 80w90 in the box with an oil stabiliser, it may prolong it slightly.
You really don't want to drive it untill somethings breaks in there, what could have been a relativly cheap bearing replacement job could turn into a major!!!

[Rod_4x4]

Thanks again lads for going to the trouble of trying to help me out. Im guna have a good look at it sunday with the old man and get whatever it is repaired/replaced asap, I'm not guna drive it untill then, which will hopefully be soon, as nearly snow time. I dont want to damage anything any further, I 'll keep you updated as you may want to know what the problem was. Anyone else with info on what it could be would be great as well. Cheers
-Rod