MG4 Reduction Gearbox Oil Leak

[Cocijo]

Plus you would have thought that it would have been subject to extensive testing?

 

[Hagen]

The breather does have ball bearing in its 4mm tube, it lifts in response to pressure from the box, exposing a little slot in the tube.
I guess at some point gravity pushing down on the ball will be greater than the pressure of oil pushing up.
At what point we get to this is anyone's guess

I suppose the ball bearing is for preventing dust to come in the gearbox. If so, and the same breather is placed in the 'Z' solution breather, could it be that some oil remains in the 'Z' when the air in the gearbox is decompressed, because the ball bearing prevents it from falling down?

 

[AndyL61]

I suppose the ball bearing is for preventing dust to come in the gearbox. If so, and the same breather is placed in the 'Z' solution breather, could it be that some oil remains in the 'Z' when the air in the gearbox is decompressed, because the ball bearing prevents it from falling down?

The breather with the ball bearing in it I believe will be on the end of the Z so should not prevent oil running back in.

 

[Hagen]

The 1,5ml oil that WigglePig mentioned, isn't that much. The 'Z' breather could contain that, I think. Maybe its building up in the 'Z' in more drives?

The breather with the ball bearing in it I believe will be on the end of the Z so should not prevent oil running back in.

When the gearbox is cooling down, it can create a vacuüm in the 'Z' that holds the oil?

 

[WigglePig]

The 1,5ml oil that WigglePig mentioned, isn't that much. The 'Z' breather could contain that, I think. Maybe its building up in the 'Z' in more drives?


When the gearbox is cooling down, it can create a vacuüm in the 'Z' that holds the oil?

Precisely so.
One poster on here has shown their large tube solution and I would imagine that would work pretty well. Or use an expansion vessel to allow the air to pass and the oil to drain back.

 

[siteguru]

When the gearbox is cooling down, it can create a vacuüm in the 'Z' that holds the oil?

Possibly. Think of when you have a straw in liquid and you put our thumb over the end ... when you pull out the straw the liquid remains inside. (A mix of lack of pressure from above, and surface tension of the liquid at the bottom).

 

[Hagen]

The 1,5ml oil that WigglePig mentioned, isn't that much. The 'Z' breather could contain that, I think. Maybe its building up in the 'Z' in more drives?


When the gearbox is cooling down, it can create a vacuüm in the 'Z' that holds the oil?

 

[Hagen]

Precisely so.
One poster on here has shown their large tube solution and I would imagine that would work pretty well. Or use an expansion vessel to allow the air to pass and the oil to drain back.

That person can check if there remains some oil in the transparent tube after driving. If so, a breather without ball bearing should solve this.
Like this.

 

[WigglePig]

That person can check if there remains some oil in the transparent tube after driving. If so, a breather without ball bearing should solve this.
Like this.View attachment 15388

Not really, since with a narrowish tube the surface tension will hold the oil there.

Anywaysup, the solution is pretty straightforward; a breather tube with a reservoir/widening/bottle to allow the air to escape and the oil to drain.

 

[Macadoodle]

When the gearbox is cooling down, it can create a vacuüm in the 'Z' that holds the oil?

That had occurred to me too. Not sure how well a steel on steel interface would hold a vacuum, but maybe the oil coating would assist it in doing so ?

 

[Hagen]

Not really, since with a narrowish tube the surface tension will hold the oil there.

Anywaysup, the solution is pretty straightforward; a breather tube with a reservoir/widening/bottle to allow the air to escape and the oil to drain.

Then you still need a breather without ball to prevent for vacuüm problem, if I am right with my 'diagnose'

 

[horse7]

Good to see so much expertise out there, I wonder if the experts at SAIC have a solution with the MG4,s that are being produced in the factory at the moment.

 

[Hagen]

Patented Macadoodle oil breather fitted today, zero leaks so far after 40 miles, some on 70 mph section.View attachment 15381

Good news!
Maybe there isn't any leak so far because the oil is building up in the 'Macadoodle' if the MG breather makes a vacuüm? I am not sure about that, maybe you can look sometime if thats the case?

 

[Macadoodle]

Well, another 50 miles covered today, some at 75mph. No leaks whatsoever .
Doesn't look like the oil is making it up the pipe very far, can't really see any evidence in the pipe in fact.
I filled the box with 870ml to allow for some oil still being in there.
We'll see what happens in the warmer weather but pleasantly surprised so far

 

[Hagen]

View attachment 15391
Well, another 50 miles covered today, some at 75mph. No leaks whatsoever .
Doesn't look like the oil is making it up the pipe very far, can't really see any evidence in the pipe in fact.
I filled the box with 870ml to allow for some oil still being in there.
We'll see what happens in the warmer weather but pleasantly surprised so far

Thats no oil beneath the orange cables?

 

[siteguru]

Oil mist coating, above the cable clamp (IMHO)

 

[Hagen]

Okay I assume that some oil mist is normal. The MG 'Z' solution still leaks by a lot of cars and the 'Macadoodle' not.
Iam wondering if the reason is the different length and/or the stand of the breather: upright in the 'Z' (maybe vacuüm problem) versus diagonally (less chance on vacuüm).

 

[Macadoodle]

To be honest when I looked at it after the journey and took the picture, the pipe looked pretty oil free inside, even in the clamp area.
I think the brass of the threaded tube I used is giving the yellow look.
Either way, a little misting in the lower section of tube will be fine, outside is totally dry, ran my finger all around the joins to be sure.
I'm just pleased that I've found a way of letting the unit have its full 900ml of lubricant, its a really unfair game MG are playing with their customers regarding the 750ml recommendation.

The oil cools as well as lubricates, come summer there's going to be some stressed MG gearboxes in hot climates I think.

 

[Hagen]

Good to hear. Thanks for your 'homework'! Do you think that 'vacuüm' might also be part of the problem?

 

[the briggie]

As a matter of interest has it actually been confirmed that there is no liquid cooling around the reduction gearbox and that the internal lubricant is the only cooling method?