MGB-GT Gearbox oil change

[ormsky]

How difficult a job is it to change the gearbox/overdrive oil on an MGB-GT (1970)?
The drain plugs are easy enough to get to but I cant see any way to access the filler/dip stick (I'm not even sure where it is?).
Can this job be done with the gearbox in the car or does it need to be removed first?

Thanks!

[heebeegeetee]

You can do it with box in car but it is a bit fiddly.

Behind the centre console thingy, on the drivers side is a flap of carpet. (or there should be unless a previous owner has been careless with the new carpets!) Under this flap is a large rubber bung/grommet thing. Under there is the dipstick, you might have to grope around for it.

The dipstick hole is also the filler IIRC. When I did mine, I got one of those flexible funnels with a flexy spout on it, know what I mean? I then taped a good length of clear tubing to the spout. I used enough tubing so that I could suspend the funnel at about head height, (hung from the garage roof) and poked the tubing through the hole in the bodyshell into the gearbox filler. I then carefully poured the fresh oil in. By having the funnel quite high means the oil will flow a bit quicker, and the clear tubing allowed me to see what was happening.

I dare say others have different (and possibly quicker) methods, but my viewpoint was that a good quantity of spilt oil into the carpet in the inaccesible area that it is would be a complete disaster, so I took it v carefully indeed. Plus you can leave the funnel and tubing hanging overnight so that the oil drains thoroughly into the 'box.

There are some good websites around, not least this one which has an MGB technical board. They're mostly yanks posting here, but they're very knowledgable and hel[pful.

http://www2.mgcars.org.uk/cgi-bin/gen

Oh, forgot to say, this is how to do it on an earlier car. Mine is a Mk1 '67.

[heebeegeetee]

Ah-ha! I see you have already been there.

[ormsky]

Yes, thanks for the reply. I'll have another go tomorrow.

Edited by ormsky on Saturday 24th February 18:51

[niva441]

I didn't realise there was a filler access hole.

I filled mine up by taking the filler plug out then filling the gearbox with siphon tube running up through the engine bay.

It did take some time though.

[wadgebeast]

Don't forget to use the proper oil! Gearbox oil is too thin and will affect the overdrive unit.

[niva441]

Yes the proper oil spec surprised me and I had to check a couple of sources to confirm. Especially as my BV8 used conventional gear oil, not engine multigrade - expensive when you use the Castrol Classic.