Noise that stops with clutch pressed

[moyesboy]

My recently acquired 2002 2.7 LWB is in nice nick 81,000 miles, but there is just this one thing that worries me.
From inside the vehicle with the gearbox in neutral it sounds like the exhaust is blowing slightly, but it stops when the clutch is pressed.
I missed this issue before I bought it because the front exhaust was sheared at the flexi. and I assumed it was that (I fixed that).

When driving there is a bit of transmission noise, which is again quiet with the clutch pressed in - it follows engine revs, not wheel revs. At higher speed it has a slight throb to it, nothing that noticeable though.

I haven't experimented yet with the transfer box, I'll see if that changes the noise.

Perhaps its the clutch release bearing but in my experience on other vehicles that is noisy with the clutch pressed in. This is the opposite.

I searched out this thread where something similar is discussed but no real conclusion reached:
http://www.nissan4x4ownersclub.com/forum/showthread.php?t=5452&highlight=GEARBOX+NOISE&page=2

I'm hoping that as one of the guys in that thread swapped the gearbox and it made no difference it might not be anything too expensive!

This is my third car to get me through the snow this winter, and up a few mountain tracks next summer. My intention is to keep driving it and see what happens. As a third car I can tackle a few jobs myself. What I've done so far I've quite enjoyed.
Hopefully it is something that I can leave until it is worse, or something I can tackle myself.

 

[exosteve]

its sounds like one of your gearbox bearings. mine sounds terrible but keeps going. most peoples opinion is don't bother fixing till its broke.

 

[puddle hoppers inc.]

i believe you can get additives to help with the symptoms, available at most outlets, in yesteryear it was a bit of sawdust added to the oil.....

 

[exosteve]

another tip was to jack up the gearbox to fit more oil in

 

[Sweety]

Sounds as if it's the lay shaft bearings, over filling the G/box by around 1/2 litre of oil seems to help a bitMy last T2 rattled away when I bought it & I put over 40K on it & 2nd gear was just starting to get a tiny bit stiff now & again when I sold it so it would have gone on for longer

 

[moyesboy]

I just changed the gearbox oil. After a bit of a run it doesnt seem so bad. Must get it on the breakdown insurance.
By the sound of it it should get worse and warn me before it leaves me stranded? All the gears change nicely and all sound the same.

 

[R1cho]

there will be a lot left in it yet, mines done it since i got the truck and i've done over 20k in it

 

[Sweety]

They don't just pack up it'll rubble badly first but adding extra oil helps as the bearings are set high up in the box & don't get a great covering of oil which is why the wear badly/fast. The was a few threads about this around 6-7 years ago

 

[rustic]

i believe you can get additives to help with the symptoms, available at most outlets, in yesteryear it was a bit of sawdust added to the oil.....

Molyslip, i have posted this several times, there are two additives, multiglide and molyslip G
I was hearing a slight noise as I decelerated towards junctions, this was years ago, and many tens of thousand mies ago... the molyslip dropped the noise to less than 20% and you can't hear anything these days... pardon, what...

I'll have a look...
edit.. try this..

http://www.nissan4x4ownersclub.com/forum/showthread.php?t=1747&highlight=molyslip


The primary input shaft, lay shaft bearing is starved of oil and an extra 200 ml of oil in the main gearbox helps.


Rustic

 

[rustic]

This is what I posted... and that was 6 years ago....


I had similar problems with my MkI 2.7TD, when slowing down through the gears, I had this whine...
I used molyslip in March 2007, this is what I wrote on a previous thread.

I have now changed the gearbox oil, added 105ml of molyslip G and 100ml of multiglide, I jacked up the passenger side and overfilled by approx 200ml, I took her for a 20 mile drive to get the oil circulating, and 2 days later the gear box noise has reduced by 80% I could not believe it.
I did the transfer box, but only added 50ml of G and 50ml of multiglide.
Tip, in order to fill the gearbox and avoid gear oil running down your arm, get a 1 metre length of garden hose with a funnel at one end open the bonnet and thread the hose down the back of the engine, ty-wrap the funnel to the fuel filter hoses then go below and position the pipe into the fill hole, but wedge it up so that the pipe flows down into the gearbox, otherwise the oil will run back along the hose.
Warm the oil container first (in a bucket of hot water) and it goes in a treat.

Worth a try, still drives well, no major noise now, there is still some whine but it's probably ok for another 2 years I guess..
Hope this helps.
Best regards, Rustic

 

[moyesboy]

I put some GL5 left over from the front diff in with the GL4 in the main gearbox.
But although I was told the difference was only to do with its heat capability (gas limit) I've now read elsewhere that GL5 might have additives that could eat some oil seals and synchro rings in there.
Any truth in that?
Its EP80W-90 GL-5 (not the special stuff spec'd for the limited slip rear diff).
Unless the advice is to get all that changed out...
I'll tip it over a bot and get some more in, unless anyone wants to explain about how to pour it in through some sort of gear change hole at the top...

 

[geoffdown]

I put some GL5 left over from the front diff in with the GL4 in the main gearbox.
But although I was told the difference was only to do with its heat capability (gas limit) I've now read elsewhere that GL5 might have additives that could eat some oil seals and synchro rings in there.
Any truth in that?
Its EP80W-90 GL-5 (not the special stuff spec'd for the limited slip rear diff).
Unless the advice is to get all that changed out...
I'll tip it over a bot and get some more in, unless anyone wants to explain about how to pour it in through some sort of gear change hole at the top...

Yes get the gl5 out asap not good with brass . I just jack up and support passenger side a bit tp allow more oil in think on level the gearbox is full with 5l but put say another 200 mm in .tip boil kettle and put in bucket place 1l bottles in there so they get nice and runny and easier to squeeze in:thumbs

 

[firebobby]

As above, GL5 eats the bronze in our gearboxes, get it out ASAP and fill with GL4

 

[moyesboy]

GL5 out, GL4 in and tipped it on ramps to get at least 500Ml extra in there.
Thanks for the advice. I'll see how it goes.

 

[stevo]

So, given I have the same noise with clutch pedal up, and knowing its the layshaft, I've added extra oil, and some molyslip.

The results? Intermittently quieter with the clutch up in neutral, generally quieter when driving (to be more specific, if I labour it slightly uphill, there is a lot less vibration), and gear changes are smoother.

Hopefully, a bit more life given to the gearbox, layshaft bearings etc.

I'll get mine overhauled when the clutch goes (the biting point is low, so might be soon)