It might be shards of metal in your gearbox. Change the oil and check that magnetic drain plug. I had half a teaspoon full of pig iron bits in mine and the noise disappeared when they did.
Don't be daft, they're made up. Grungle pins are actual things, I've read about them in motoring mags.
What does good oil look like? Don’t waste your money on Molyslip; change the gearbox oil to a fully synthetic GL4 such as Castrol Syntrans Multivehicle 75w-90, if it still makes a noise, and it probably will, it’s not caused by the lubricant.
I changed the gearbox oil when I got home today, admittedly not the best oil but it's a gl4 75-80w as that's what I could get, took it for a run and seems smoother and quieter but it making a bit of a noise in 1st and 2nd now, it does it if I'm parked up and rev it hard does this change anything? Is it my choice of oil, or still the gearbox?
Things that make bad noises when you rev it up and it is parked may include alternator bearings as well as the gearbox. It turns out that 0.2mm of radial play in the front alternator bearing can make the engine twice as loud and it sounds nasty. The bearing costs £3.50 if you have the tools and the time. Thicker gearbox oil will silence the whining noises a bit, so if you put thinner oil in it will be a bit noisier. Gearbox whining may just be something you can live with - my gearbox was changed around 40000 miles ago and the 'new' one was very noisy and it seems to have got quieter over time. But if there is a noise getting worse fairly quickly then that may mean rapid wear or something is coming undone. Also check the endfloat by pulling and pushing on the engine pulley that drives the alternator - if it moves in and out more than a little bit (0.14mm) then things need checking - I have had two incidents where the flywheel came loose creating severe vibration and the symptom of this is that as the flywheel loosens the endfloat increases. In one case it was my numpty self leaving the big nut holding on the flywheel undone, and the second time the flywheel came off was because of massive vibration from losing an exhaust rocker at 60mph. The first time the engine was repaired and the second time was new engine time. Post a video , the sound may prompt somebody.
I dont think this problem is linked but my carb seems to stick every now and then, if I push the throttle down with my finger it will stop at sort of 90 degrees but every now and then I can push it and it will go all the way, this happens if the engine has been running or if it's cold. Is that normal or is it worth stripping it and cleaning the carb up?
Have you bought some recently ..i think you might be a bit disappointed , After market grungle pins ...i ask you
Have you checked the adjustment you should have about one inch free play at the pedal, if it only happens when you depress the clutch pedal it could well be your release bearing, would change it before your long trip if it is faulty
It doesn't seem to do it when the clutch is depressed it's as I let off the accelerator it becomes noticeable
So, to summarise, you started to have a grinding noise in 3rd and 4th gears when you decelerated. You changed some good looking gearbox oil for something that’s not the best and now it makes a scraping noise in 1st and 2nd when stationary revving the engine. It makes the noise when the clutch is engaged but not while accelerating. It sounds to me more engine related than gearbox. Does the frequency of the noise change with road speed or engine speed? Is the fan touching the shroud? Is there something jammed in the fan? How much crankshaft end float do you have? Is it a type 4 or type 1 engine? It’s obviously not normal that the throttle sometimes sticks 90deg open but I doubt if it’s relevant to the problem.
