mgb gt overdrive problems help

[llohcins]

Hi, I have an mgb gt 1979 with overdrive. this seems to have stopped working in the last month. A mate of mine says its the solenoid. Is this an easy fix? To be honest even though i have a manual and i am usually alright at these things I have never had to play with an overdrive before and I am not 100% sure where it is, is it inline with the gearbox, inside it or to one side? looking in th manual it seems that once i find the thing its an easy unbolt and replace but an overdrive is a bit misterious to me. Any advice would be much appreciated, thanks

[MG CHRIS]

Another thing you need to look at is has the wires came of the bottom of the gear stick that what had happened to ours check that you have live and earth on the wires to the bottom of the button on the overdrive switch other than that check the fuse if it has been working recenctly it more than likly it something like that rather than the overdrive unit that need to be replaced they are normally bullet prof. Im not sure how easy the solenid is to replce but should be easy to do

[saxxeblt]

Yep, check the wires are connected in the switch, if they are, put a test lamp on to see if there a current. Ignition on of course and in 3rd or 4th gear, which is when the O/D works. If no current, it's likely it's a wiring or electrical fault.
HTH

[SB - Nigel]

I agree with Chris and sax it's likely to be the wire(s) to the switch as the way they run to the gear lever is sublect to wear (but of course check other suggestions first)

Whilst you're at it if, before it stopped working, the overdrive did not almost instantly drop in or out then you should try cleaning the O/D filter plate which must be very easy to do as I've done it and I'm ham-fisted and slow witted as regards mechanical things

Changing the gearbox oil every three years is also a goood idea I think (no lubricating aditives these times tho' as it's an O/D box)

If you don't know when the gearbox oil was last changed or it was more than 3 years ago then change it giving plenty of time for the old oil to drain

I always recommend doing a full and proper 36,000 mile service if the car is new to you or you don't know when the last full and proper 36,000 mile service was done

Also having an owners Handbook instead of or as well as something like a Haynes

[alfa pint]

Agree with the others - tends to be broken wires before the solenoid goes. Also, if you do change the oil make sure it's engine oil not gearbox oil. The overdrive needs the extra viscosity to work properly.

[SB - Nigel]

alfa pint said:

Also, if you do change the oil make sure it's engine oil not gearbox oil. The overdrive needs the extra viscosity to work properly.

The owners Handbook would tell you

[K williams Wood]

I'm having an issue with my over drive, Normally you feel it kick in but now when in 4th you don't feel any difference when you throw the switch, and the revs remain high. When you turn it off however you do feel a slight drop. Can anyone help what should I be looking at?

[PositronicRay]

K williams Wood said:

I'm having an issue with my over drive, Normally you feel it kick in but now when in 4th you don't feel any difference when you throw the switch, and the revs remain high. When you turn it off however you do feel a slight drop. Can anyone help what should I be looking at?

What do you mean "a slight drop" I'd start by looking @ the electrics, switch & wiring etc.