Reduce noise in worn gearbox that's not worth repairing

Peterbilt

Evening all, Anyone got any ideas? Car is 20 year old 1.0 Micra worth maybe
€100. Dont know which bearing or bearings is worn, input shaft maybe. Clatter largely disappears when clutch pushed to floor. Worse in mornings when cold. Was thinking of refilling box with 140 gear oil to replace the 80/90. Also, Lucas make an additive for noisy boxes, Heavy Duty Oil Stabilizer, but its expensive.
I've thought of replacing with box from breakers but that'll cost region of
€300 all in, and no guarantees regarding the internal condition of box from breaker's yard. My 8 year old little fella drives it around the farm and he has me damned with his pleading for me to fix it.
Someone suggested sawdust, someone else oatmeal :eek:

porsche boy

If noise disappears when you put your foot on the clutch then it's the release bearing. Changing oil or adding additive won't make a difference as the bearing in question isn't 'in' the gearbox, so to speak. It's part of the clutch set up.

Peterbilt

I would have thought if it was the clutch throw out bearing it would be noisy when the clutch is pressed? And it would be a different sounding noise? This is a clatter when the car is ticking over, as well as when its driving. Noise mostly stops when the clutch is pressed to the floor.

blackbox

If it really is the gearbox that's making the noise, replacing the oil with new oil of the correct grade or very slightly thicker may help.

Adding 140 oil will make gear selection very difficult when cold, as well as not lubricating properly.

rex-x

porsche boy wrote: »

If noise disappears when you put your foot on the clutch then it's the release bearing. Changing oil or adding additive won't make a difference as the bearing in question isn't 'in' the gearbox, so to speak. It's part of the clutch set up.

Actually if it disappears when you push in the clutch its usually the main input shaft bearing on the gearbox very common problem mostly misdiagnosed

Peterbilt

rex-x wrote: »

Actually if it disappears when you push in the clutch its usually the main input shaft bearing on the gearbox very common problem mostly misdiagnosed

That's what I was thinking too. The capacity of the gearbox on the 1.0 Micra is 3L. I was thinking 1L of 140 gear oil, 1L of 80/90 and 1L of Lucas Heavy Duty Oil Stabilizer. Wouldn't cost much more than €30. What do you think? Cant make it any worse surely.