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MG MGB Technical - overdrive oil drain

I've just changed the gearbox oil and note that I also need to drain the overdrive unit (Laycock). Also I need to remove and clean the filter in the overdrive. I can not see a plug labelled 'DRAIN'. Is it the one next to the name plate? If not the only way I can see to get the oil out is to remove the inspection plate. Should I expect any problems?
Steve Church

I've just seen the University motors video on Youtube. Just have to let the oil run out. The filter has a card type gasket which has separated slightly. Are replacement ones available or do I need to use some gasket goo (Hylomar)?
Steve Church

This is no separate drain plug for the LH overdrive. Removing the filter cover will drain the overdrive sufficiently. RAY
rjm RAY

Steve,

Replacement OD filters should be available from the good parts suppliers. Weight of opinion here over years is NEVER any gasket goo (of any sort) anywhere where it may discard pieces into the OD hydraulics.

Don't overtighten the OD plate screws on re-install or you risk stripped threads or, probably worse, a distorted plate.

Regards
Roger
Roger T

*Make sure* you can remove the dipstick (CB) or side filler plug (RB) *before* draining the oil. You can live without an oil change for a bit, but not without oil.

Drain the gearbox, but there will be some more when you remove the OD sump so be ready for it. Slacken the screws round it gradually as it is relatively thin alloy so could warp. Leave the screws in two opposite corners until you have freed it from the OD, it may need a bit of careful levering, there is a large tab by the hex plug seemingly for the purpose. I did two but opted to buy only one strainer/gasket, and one did indeed rip but the other didn't :o) Which is another way of saying yes, they are available, from the usual suspects.

If you are removing and cleaning the relief valves etc. put a clean container underneath to catch any parts that may not fall out immediately. I didn't use any gasket seal and it seems to have been OK. Tighten the sump screws gradually, there is no torque figure I have seen even in the Laycock manual but overtightening is likely to warp the cover which will *cause* leaks. The smallest 'standard' value I have is for a 1/4" thread and that is 8ft lb for a coarse thread, as I recall these screws are smaller than that so 8 should be considered the absolute maximum. Small values like this are likely to be very hit and miss on a torque wrench capable of going up to say 150 ft lb, so you need to very careful. One site talks about 76 *inch* lb for that 1/4" screw because of this, but how many of us have inch pound torque wrenches?
PaulH Solihull

This thread was discussed between 23/10/2010 and 25/10/2010

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