MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Unusual Overdrive oil leak

I have been chasing oil leaks around the LH overdrive on my 73B, which I have now successfully resolved, so I detail the resolution here as I could not find any reference to it in the archives.

Background:
I have successfully replaced the rear oil seal which was leaking along with the two seals associated with the speedo gear drive. I addition I have replaced the three O rings, gasket and cable seal that are associated with the solenoid.
This resulted in a reduction in the oil forming at the bottom of the overdrive. However there was still a small amount of oil forming on the lower radius of the rear casing of the overdrive, just a small amount enough to cover your finger after a 5 mile run.

Problem:
I traced the leak to oil seeping out from around the lower four studs, nuts and washers that fix the rear OD casing to the main OD casing. (These are items 79, 80 & 81 detailed in section Fc, page 2 of the 15th edition of the workshop manual (part no. AKD 3259))
After cleaning all nuts with carb cleaner, and another short run, there was oil evident around the nuts and on the lower of the rear casing, but above the filter/sump gasket.

Resolution:
To resolve this I have fitted a fibre washer (to form a seal), then a plain washer (to compress the fibre washer), spring washer and the nut in that order, and this has resolver the leak. I removed each nut one at a time so as not to disturb the mating of the rear casing to the main casing. This was done with the OD in the car from below. The nuts are easily accesses with a small 7/16” socket and retorqued to the same tightness. I repeated the same 5 mile run and no oil leak.

I attach a picture of one of the studs, immediately after removel and you can see the oil on the shaft. I will post a second picture of the four nuts in question in a moment.

Has anyone come across this problem and can anyone comment on my resolution? I have no idea how oil is getting into the studs, but it was coming out.
Hope this helps others.

Richard



Richard Thompson

Second picture

Richard Thompson

Richard I have come across this before, and have fixed the oil leak with using a copper washers, the first time I did this I had the box on the bench, and I pressurised the box with air, and I could see exactly where it was leaking, after I had sealed it I retested it and no more leaks, A.T
andy tilney

well done
Nigel Atkins

Very good. Just like leaks from the thermostat housing bolts.
Paul Hunt

Thank you for your remarks.

Andy,

I would have preferred to use copper washers but I only had fibre ones to hand. Thanks for the suggestion.

Richard.
Richard Thompson

This thread was discussed between 04/05/2014 and 05/05/2014

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now