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Hope some of you can help with these:

1. I am getting a strange knocking noise which sounds, and feels, like it is under the driver's seat. It mainly happens on bumpy country roads, but not necesarily when driving over bumps (!) and usually happens in 2nd or 3rd at about 20 - 30 mph. Have thought it could be exhaust banging the car, CV joints, wheel bearings, rear suspension???

2. Oil leak. The oil looks like it is coming from the bottom of the gearbox, but I am hoping that it is engine oil that is just running down the gearbox and collecting at the bottom of it. Any way of telling what oil it is? My engine oil is pretty clear as I have recently changed it so that isn't much help. If it is gearbox oil, how do I check the oil level and how do I top it up. I have found a white plastic plug at the top of the box. Is that the filling point?

3. I fancy cleaning the breather. Is it better to get to it from the top or the underneath of the car?

Ta, hope you can help.

whatever you do dont fill through the white plastic bung that'll put oil all over your clutch!!!!! the oil fill bungs are on side of the box below the dizzy!

Have looked below, but still can't find the gearbox oil filler. And what do I do when I do find it? Fill it until oil starts coming out the hole?

the fill & drain holes are both on the side of the diff housing of the gearbox where the near side driveshaft attaches. The filler plug is next to the driveshaft & the drain is below it. If you change the oil (which is a good idea now G40s are getting old), fill it back up to the bottom of the fill hole which takes up about 3.5-ish litres.

Check the sump gasket for leaks, this is quite common & can blow onto the gearbox when the car is moving.

You'll know if it's gearbox oil as it REEKS of cat p***. Open the filler hole & have a sniff. then compare that with the stuff on the bottom of the box.

You need a 17mm hex key to undo the plugs by the way.

Maybe thinking about changing my gear box oil, is there actually any point? Is it easy to do and does it take any special oil because it is a G40.

OK, thanks. The sump is leaking a bit so hopefully that's all it is! I'll check the gearbox oil level, and maybe change it anyway.

Anyone got any ideas about my knocking?

polo_GT wrote:Maybe thinking about changing my gear box oil, is there actually any point? Is it easy to do and does it take any special oil because it is a G40.

yes there is a point to it. The oil in there will be about 13 years old & it's being relied on to lubricate the gears. Without it your box would go bang in a matter of a few miles. Although it doesn't get contaminated like engine oil does it still wears out & stops lubricating as well. G40 gearboxes aren't exactly easy to get hold of so it's worth taking care of it.

I can't remember the grade of GB oil to use but Haynes will tell you. It's nothing special for a G40 box. Unless you have an LSD fitted which uses different oil.

Thanks for the help.

Have changed the sump gasket so will see how that goes.

The banging has turned out to be the exhaust hitting the car.

Thanks for the help.