1970 MGBGT overdrive , gearbox leak (help!)
Discussion
Hi all , not my car but a friend has the above car all body work restored and resprayed last year. Since he started using it he has noticed it using a small amount of engine oil and more worryingly a steady leak from the gearbox when hot, dripping it seams from the centre area of the box . When cold it stops !
I have been roped in to assist as I have a reasonable sized well equiped garage and a fair amount of engine change expearience but have never done an MGB!
Our current thinking is that an oil seal on the box has failed so we need to remove and replace the seals what else could we need?
The owner has decided its best to remove the engine and box together, I have a good engine crane so thats possible, but is it the best way? I should say I have removed and swapped engines both ways before just not on a B!
Is it easier to remove the box from under the car, car on ramps then jack up the front on stands? (I may have access to a 2 post ramp if this is much easier?)
Are there any pitfalls we need to be aware of either way?
we have engine crank seals incase and a clutch to put in as its coming out and full gasket set available. Is there anything else we should do while it is out?
Speedo has failed ( could that be the source of the leak?) so we have new drive mech and cable to fit, any tips for this?
Finally is there any guide to how long it should take to remove split and reassemble and refit so we allow enough clear time ?
Many thanks for all your help
steve
I have been roped in to assist as I have a reasonable sized well equiped garage and a fair amount of engine change expearience but have never done an MGB!
Our current thinking is that an oil seal on the box has failed so we need to remove and replace the seals what else could we need?
The owner has decided its best to remove the engine and box together, I have a good engine crane so thats possible, but is it the best way? I should say I have removed and swapped engines both ways before just not on a B!
Is it easier to remove the box from under the car, car on ramps then jack up the front on stands? (I may have access to a 2 post ramp if this is much easier?)
Are there any pitfalls we need to be aware of either way?
we have engine crank seals incase and a clutch to put in as its coming out and full gasket set available. Is there anything else we should do while it is out?
Speedo has failed ( could that be the source of the leak?) so we have new drive mech and cable to fit, any tips for this?
Finally is there any guide to how long it should take to remove split and reassemble and refit so we allow enough clear time ?
Many thanks for all your help
steve
You can't remove the gearbox separately on the B and it's best to take it out with the engine and do the same to put back in. Having said that, make sure it's not the overdrive filter that's not leaking first as you can do that in situ from under the car.
If you do have to remove the engine it needs to come out at an angle which means the front of the car needs to on ramps and the gearbox crossmember needs to be unbolted and the box supported until you are ready to pull the engine from the car. If you've got the angles right it'll come out of the front of the car and clear the slam panel, with the rad panel removed of course.
Ideally you need two people once you've unbolted everything, it's not too hard and replace the clutch unless it's new or recently fitted, just makes sense in the long run.
HTH
If you do have to remove the engine it needs to come out at an angle which means the front of the car needs to on ramps and the gearbox crossmember needs to be unbolted and the box supported until you are ready to pull the engine from the car. If you've got the angles right it'll come out of the front of the car and clear the slam panel, with the rad panel removed of course.
Ideally you need two people once you've unbolted everything, it's not too hard and replace the clutch unless it's new or recently fitted, just makes sense in the long run.
HTH
As above, plus the following note:
- double check it's not the seal around the panel for the overdrive filters.
Gearbox cables are notorious failures and is not necessarily connected to the gearbox leak. It's a mechanical spindle and the end just wears out rather than coming off and allowing a leak.
- double check it's not the seal around the panel for the overdrive filters.
Gearbox cables are notorious failures and is not necessarily connected to the gearbox leak. It's a mechanical spindle and the end just wears out rather than coming off and allowing a leak.
Shouldn't have to replace the filters as they're gauze, just clean them. Not too awkward to replace the seals (very vague memory from years ago). Just in case you didn't already know - don't replace the oil with gearbox oil as it's the wrong viscosity for the overdrive. Engine oil is the way forward.
Sounds to me like the best course of action is to clean the whole area to find the actual leak source(s), then check the gearbox leak first and resolve - as others have said, it may be as simple as the overdrive filter cover gasket as the culprit, or indeed the side cover over the gears themselves if the leak is in the centre of the box, and may just be a gasket alignment/fit issue.
Engine oil leaks are not uncommon - it is not oil tight like a modern engone - and if not serious, particualrly if there is nothing actually wrong with the clutch/gearbox, might well be best tolerated unless the engine is seriously incontinent. Oil leak sources may be the crank seal or the sump gasket, particularly in the centre near the rear main bearing cap.
If you do end up wanting/needing to remove the engine and gearbox, the engine can be removed separately, as long as the gearbox is properly supported as you slide the engine forwards, or you risk shagging the gearbox input shaft seal as you remove it or mate the two back together - and when replacing the engine with the gearbox still in the car, it is difficult to align the engine and gearbox properly before pushing them together. It can be done, but if not familiar with the car, best remove and replace the two as a single unit. However, if using ramps or a 2 post lift to be able to get under the car to undo mounting bolts etc, suggest that you use them to be able to disconnect all the ancillary components (e.g. clutch slave cylinder, starter motor, propshaft etc) first, but when you come to remove the engine mounts and gearbox cross-member, better have the car off the ramps, otherwise you need an engine hoist with a heck of a high lift and one that is easy to move with the suspended weight, if you're bringing them both out as a single unit. This is due to the length of the combination and angle needed to clear the back of the gearbox on front of the car. Better to lift the combination gradually and move the car on its wheels rather than having the move the engine hoist.
MG Mark
Engine oil leaks are not uncommon - it is not oil tight like a modern engone - and if not serious, particualrly if there is nothing actually wrong with the clutch/gearbox, might well be best tolerated unless the engine is seriously incontinent. Oil leak sources may be the crank seal or the sump gasket, particularly in the centre near the rear main bearing cap.
If you do end up wanting/needing to remove the engine and gearbox, the engine can be removed separately, as long as the gearbox is properly supported as you slide the engine forwards, or you risk shagging the gearbox input shaft seal as you remove it or mate the two back together - and when replacing the engine with the gearbox still in the car, it is difficult to align the engine and gearbox properly before pushing them together. It can be done, but if not familiar with the car, best remove and replace the two as a single unit. However, if using ramps or a 2 post lift to be able to get under the car to undo mounting bolts etc, suggest that you use them to be able to disconnect all the ancillary components (e.g. clutch slave cylinder, starter motor, propshaft etc) first, but when you come to remove the engine mounts and gearbox cross-member, better have the car off the ramps, otherwise you need an engine hoist with a heck of a high lift and one that is easy to move with the suspended weight, if you're bringing them both out as a single unit. This is due to the length of the combination and angle needed to clear the back of the gearbox on front of the car. Better to lift the combination gradually and move the car on its wheels rather than having the move the engine hoist.
MG Mark
Edited by MG Mark on Tuesday 26th October 23:01
Quick update car all in garage on ramps at rear and stands at front - think we have found our leak from the overdrive unit solenoid cover ( the one with the writing on ) bolts were barely finger tight and there is a gasket under it so we assume that it is open to oil on the inside? Does anyone know how tight what torque they should be ? Also any tips ie should we use any sealant with the new gasket ( which we have ) or any thread lock on the bolts? should there be washers under each bolt?
We plan to do this tomorrow as tonight we have cleaned it with brake cleaner and cloth found it dripping and tightened the loose bolts tomorrow we plan to change gasket and also the filter and gasket next to it as we have one of those as well then top up gearbox.
I am so grateful for the help so far you have saved us so much time and hassle .
We plan to do this tomorrow as tonight we have cleaned it with brake cleaner and cloth found it dripping and tightened the loose bolts tomorrow we plan to change gasket and also the filter and gasket next to it as we have one of those as well then top up gearbox.
I am so grateful for the help so far you have saved us so much time and hassle .
Yes, that is open to the oil inside. IIRC it should be a rubber gasket under that plate; not sure what the torque figure is, but they are not big bolts (3/8" AF?), so not much torque and you should not need gasket sealant as well; torque should be enough to pinch down the gasket and flatten spring washers under the bolt heads. Thread lock on the bolts would be belt 'n' braces. It is the sort of component that when installed properly should not work loose in use.
Broken speedo cable should be a simple case of take out the old and replace with the new; just make sure you line up the cable and knurled retaining nut to avoid cross threading; if it is difficult to screw on, either the thread needs cleaning or it is misaligned - it should screw on by habd for most of the thread.
As for the split gaiter on the clutch actuator (presumably the outer rubbber seal on the slave cylinder bolted to the gearbox bell housing), make sure there is not a leak from within the cylinder itself while you are replacing it ; if there is replace it - it's not expensive and worth doing while you are under the car.
MG Mark
Broken speedo cable should be a simple case of take out the old and replace with the new; just make sure you line up the cable and knurled retaining nut to avoid cross threading; if it is difficult to screw on, either the thread needs cleaning or it is misaligned - it should screw on by habd for most of the thread.
As for the split gaiter on the clutch actuator (presumably the outer rubbber seal on the slave cylinder bolted to the gearbox bell housing), make sure there is not a leak from within the cylinder itself while you are replacing it ; if there is replace it - it's not expensive and worth doing while you are under the car.
MG Mark
Well thanks to you all! We have had a great day gearbox leak sorted . It was the small plate over the solenoid and all is now good , the only issue we found is that the magnets in the lower filter pan are missing so we need to source some if anyone knows the dimensions that would be handy?
Speedo cable sorted all working and to top it off we fitted a pair of K&N filters with stub stacks inside and it sounds lovely!
Greased all the nipples and replaced the two 6mm fuel pipes as they were cracking so a potential problem found and averted.
Does anyone know if you can still buy the su jet adjuster spanner ( think gunsons used to make one ) we have searched and cannot find one?
Many thanks for your assistance and what a lovely car to work on !
Speedo cable sorted all working and to top it off we fitted a pair of K&N filters with stub stacks inside and it sounds lovely!
Greased all the nipples and replaced the two 6mm fuel pipes as they were cracking so a potential problem found and averted.
Does anyone know if you can still buy the su jet adjuster spanner ( think gunsons used to make one ) we have searched and cannot find one?
Many thanks for your assistance and what a lovely car to work on !
You mean like this?
http://www.sucarb.co.uk/productDetail.aspx?id=3203...
Glad you did the job and enjoyed doing it!
MG Mark
http://www.sucarb.co.uk/productDetail.aspx?id=3203...
Glad you did the job and enjoyed doing it!
MG Mark
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