6 replies to this topic

[MFM]

Seems like a simple question but I replaced the oil in my M21 (XU1) by filling it up through the side filler plug until it flowed out then tightened the plug. Now this car was sitting for 20 years in a shed unstarted. After replacing the oil I reversed the car out of the garage back up a slight incline driveway, then back into the garage. The car is unregistered so I can't take it for a drive. Next day there was a pool of nice clear gear oil under the rear of the engine about 6" in diameter. Its definitely gear oil, no-one can mistake that smell. I assumed the front seal of the gearbox may be stuffed but was advised yesterday that there is no seal as such and that I have probably put too much oil in the box and when I reversed up the driveway it has caused the gear oil to pool to the front of the box and out the input shaft. I was told to only put in 1.4 litres. Does anyone know what's going on here. Do I have a front seal in the gearbox which is supposed to stop this? Is it incorrect to fill the box with oil the way I did?

[S pack]

Hello Mark,

 

The XU1 M20 holds 3.4 imp pints or 1.9 litres of oil. I assume you drained all the old oil out and refilled the box with the car on level ground?

 

An original XU1 M20 has the oil slinger on the input shaft whereas the aftermarket XU1 input shafts require an oil seal.

Oil leakage from the front of the aussie 3 & 4spd boxes when parked facing nose down on steep hills was an issue which led to GMH changing over to oil seal input shafts on all the Aussie 3 & 4spd boxes in early 74.

XU1's did not receive this upgrade as production had ceased before the end of 1973.

Edited by S pack, 06 November 2018 - 08:16 PM.

[MFM]

Thanks fore the explanation Dave. Seems like the answer may not be that simple after all. Does this mean if your XU1 gearbox is untouched original it probably leaks when the nose of the car is on a downhill slope? Yes I did drain the oil and fill it on level ground. Can't see how you can overfill if you use the filler plug as the tell tale of when its full but mabey I gave it one last squeeze of the oil bottle before I put the plug back in which might have caused this leakage. Probably find that all XU1's leak then find their level over a period of leakage. The box was quite wet with oil when I 1st crawled under this car before I dropped the old oil so perhaps the slinger is worn out because I spoke to the previous owner and the owner before him which takes it back to about 1978 and both said they never touched the gearbox. 

[S pack]

Thanks fore the explanation Dave. Seems like the answer may not be that simple after all. Does this mean if your XU1 gearbox is untouched original it probably leaks when the nose of the car is on a downhill slope? Yes I did drain the oil and fill it on level ground. Can't see how you can overfill if you use the filler plug as the tell tale of when its full but mabey I gave it one last squeeze of the oil bottle before I put the plug back in which might have caused this leakage. Probably find that all XU1's leak then find their level over a period of leakage. The box was quite wet with oil when I 1st crawled under this car before I dropped the old oil so perhaps the slinger is worn out because I spoke to the previous owner and the owner before him which takes it back to about 1978 and both said they never touched the gearbox. 

The slingers don't wear out.They don't rub on anything. I can't say I've ever had any leakage from the front my gearbox from parking nose down on steep grades.

You may have a leak issue with the gasket between the gearbox and the input shaft cover?

 

I found that filling the box from dry with 1.9 litres with the car on level ground the oil level sits about 5mm below the filler plug hole. 

[MFM]

Ok thanks Dave. I'll unscrew the plug today and see what comes out. 

[RallyRed]

interesting this one...refilled my LJ 4 speed the other day, from dry.
My non gen. shop manual said 1.4 litres.
It took all but 2 x 1l bottles before it dribbled out of the filler hole.
Was confused.
Happy now I see ( as above) that its really 1.9l.( = 3.4imp. Pints)
Thanks.
and

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[MFM]

Ok been reversing up and down driveway several times and leak has totally stopped? Think you are spot on S Pack as appears gearbox seems to have found its own correct oil level by leaking out of the input shaft after I replaced the oil. Not a drop now which is great as I didn't feel like removing the box.