3rd gear whine/squeak, but only sometimes

[Zwyllie]

Hiya all,

Noticed a weird issue developing with my 3rd gear in that it makes a bit of a whiny noise, but confusingly it doesn't sound like a metal on metal clang or grind that I've heard from other vehicles before, it sounds more similar to when I've had a squeaky belt which is rather confusing me since last I checked, belts don't exactly belong in gearboxes which has me confused at what could be causing the sound.

It shifts in an out of all gears perfectly smoothly and has been driving fine in all of them too, it only seems to be once driving when in 3rd gear causing it (the noise isn't there until I am off the clutch and am moving it but being in 3rd with the clutch in produces no noise)

The weirdest part is that the noise isn't even consistent, sometimes the sound stops and drives with no problem, sometimes there is the noise, sometimes the noise starts and vanishes shortly before I'm about to shift to 4th. At least a constant metal clunk is easier to figure out than a squeak

Anybody have any potential ideas of the cause?

[King Kenny]

I had something similar after years of neglect. I finally checked the gearbox oil level and found it was very low. Topped her up again and all's well.

[Bill_qaz]

If oil level ok it could be a synchro ring.
Drain box refill with atf give it a good run, drain and refill with normal oil. ATF cleans synchros.
Check drained oil for contamination.

[kevin s]

If you are using engine oil make sure it is the classic type, modern engine oils are nothing like the mono grade engine oils around 60 yeers ago. (things like zddp aren't in there at all!)

[Zwyllie]

Hiya everyone,

thanks for the help, a gearbox oil change is exactly what she was after, I've only had her a couple weeks so working my way round the maintenance jobs and was hoping that change had been done not too long ago. Full service time this weekend so all should be buttery smooth from here on

[Bill_qaz]

Hiya everyone,

thanks for the help, a gearbox oil change is exactly what she was after, I've only had her a couple weeks so working my way round the maintenance jobs and was hoping that change had been done not too long ago. Full service time this weekend so all should be buttery smooth from here on

Simple fixes are always the best

[Zwyllie]

Hiya everyone,

thanks for the help, a gearbox oil change is exactly what she was after, I've only had her a couple weeks so working my way round the maintenance jobs and was hoping that change had been done not too long ago. Full service time this weekend so all should be buttery smooth from here on

Simple fixes are always the best

Well it would've been simple if I didn't overfill it because I read my measurement wrong and have to suck a bunch out with a hose and my mouth... Had to make it an interesting job somehow

[Bill_qaz]

How can you overfill, the filler plug is the level. Even if you filled to the top of the threads it wouldn't be way oveffilled. Cant understand why you had to suck oil out?

[svenedin]

I always fill the gearbox until it starts to overflow from the filler.

Stephen

[geoberni]

I always fill the gearbox until it starts to overflow from the filler.

Stephen

How can you overfill, the filler plug is the level. Even if you filled to the top of the threads it wouldn't be way oveffilled. Cant understand why you had to suck oil out?

Exactly...to quote the workshop manual

The gearbox must only be filled with engine oil ....to the level of the filler plug.

[Zwyllie]

How can you overfill, the filler plug is the level. Even if you filled to the top of the threads it wouldn't be way oveffilled. Cant understand why you had to suck oil out?

Quite simple really. Parking at my house isn't flat so the thread filler level ends up being raised more than flat ground and can fit more in before it overflows at the threads and there isn't any alternative flatter areas nearby didn't need to take much extra out, just enough to take it nearer the bottom of the threads when raised (nearer the top of the threads when the car is flat) for it to lubricate everything properly again. When it was over filled, the car couldn't shift into gear in the slightest and it was only after taking out the surplus out the car shifted normal again and has been shifting buttery smooth since