MG4 Reduction Gearbox Oil Leak

[Oberoy]

Just had this from my dealer, meant to be collecting our car on Sunday…

We can only be guided by MG regarding any safety – technical issues. They have said to us there is no reasons for the cars not to be driven or for new owners to continue to take delivery of their MG4

We did have similar persistent issues with ZS EV when launched and looks like when a new model is released issues are had. I see you are quite a distance from us if you do have issues so just for your own logistics do you have a reputable MG dealer close by ?

Naturally we will always strive to help you but the distance you are from us may naturally become an issue due to the distance.

On past experience the initial new model cars will have issues so maybe hang fire a little longer until MG iron out there teething problems . Naturally more than happy to look after this purchase Steve but I can see you are naturally concerned that the transmission oil issue is a concern to you and may cause you stress if the car is off the road etc .

As I said all we do is be guided by MG direct but we cannot guarantee you will not have any issues etc

Are you going to collect your car on Sunday? There is a possibility that it will leak oil on your drive. Will MG compensate you for that or for the inconvenience of having to take a new car back to the dealership for the breather tube?

Surely, as customers we should have a say in asking MG to fix the cars before selling them to us?

For sure inconsistent guidance between dealerships/MG here you are being told you car will be available others are being told it's being held until a fix applied.

 

[tsedge]

For sure inconsistent guidance between dealerships/MG here you are being told you car will be available others are being told it's being held until a fix applied.

Remember most dealerships are franchises: that means they are independent businesses making their own decisions and communication policies with their customers. Some manufacturers are good at getting their dealers to be consistent in comms, MG are not.

Some dealers will prefer to fix before release and not have the customer come back with a problem. Others want to get the cars out and worry about issues later.

 

[RichardC]

My dealer just contacted me:
"MG has confirmed there will be new design breather kit, which has the addition of a long pipe to avoid oil leakage. The kit are being prepared and estimated delivery by the second week in November. Keith is going to his very best to see if we can get a better ETA. Keith will call you tomorrow when he is back in the office."

My technical knowledge is precisely zero. So if anyone could answer my questions I would be very grateful.

1. What is the breather tube for and what is it attached to?
2. How will a longer one help?

Hopefully the answers will help me to understand the problem

Thank you

 

[tsedge]

My technical knowledge is precisely zero. So if anyone could answer my questions I would be very grateful.

1. What is the breather tube for and what is it attached to?
2. How will a longer one help?

Hopefully the answers will help me to understand the problem

Thank you

A breather is a device to let the gearbox breathe air in/out as it expands and contracts due to heating and cooling of the oil and components. If the breather is poorly designed, oil can also escape, which is not intended. One way to stop the oil escaping but still allow the air to breathe is to have a long breather pipe which stops the oil getting out.

In essence, there is a design flaw in the breather on the MG4 European gearbox which MG did not encounter with the Asian market version.

 

[RichardC]

A breather is a device to let the gearbox breathe air in/out as it expands and contracts due to heating and cooling of the oil and components. If the breather is poorly designed, oil can also escape, which is not intended. One way to stop the oil escaping but still allow the air to breathe is to have a long breather pipe which stops the oil getting out.

In essence, there is a design flaw in the breather on the MG4 European gearbox which MG did not encounter with the Asian market version.

10/10. Thank you very much. I now understand the problem perfectly.

An excellent explanation ?

 

[Jonbro]

I liked the theory someone propounded about the warped tray somehow altering the pressure dynamics of the breather pipe area, thus causing it to fail / drag in water / blow oil out intermittently.
So I would be interested to hear if anyone has the oil leak but has a perfectly formed tray

 

[WalkingBootWeather]

So, is the 'breather' effectively an expansion tank? If it is merely a longer pipe wouldn't some oil still be able to escape or debris to enter?

 

[Macadoodle]

In essence, there is a design flaw in the breather on the MG4 European gearbox which MG did not encounter with the Asian market version.

So their answer is to stick a bit of hosepipe on it. Hey, if it works and lets new owners enjoy their cars at last that's fine, just can't quite understand how this design flaw passed their testing, manufacturers usually boast about the millions of miles they cover so this doesn't happen.

Was sure we were going to be told it was just a batch of dodgy breathers, this looks more like they fell asleep on the job at the design and testing stage .

 

[tsedge]

So, is the 'breather' effectively an expansion tank? If it is merely a longer pipe wouldn't some oil still be able to escape or debris to enter?

A breather is usually some combination of hose/pipe, body and cap and is designed to prevent dirt and water ingress as well as to allow air breathing. This is why you can drive through a ford and not ruin the gearbox.

Some have speculated that the position of the MG4's breather allows oil to be flung from the gearset and then leak out. Because oil is heavy, if you orient the pipe/hose the right way and have the right length, it is effectively impossible for it to leak. So, a longer pipe might be all it needs.

 

[Diggsy]

Has there been an official comment from MG yet, aside from what some users have been told by their dealerships?

Don’t recall seeing anything from Miles, aside from his comment yesterday about MG notifying dealers of the fix today.

 

[tsedge]

So their answer is to stick a bit of hosepipe on it. Hey, if it works and lets new owners enjoy their cars at last that's fine, just can't quite understand how this design flaw passed their testing, manufacturers usually boast about the millions of miles they cover so this doesn't happen.

Was sure we were going to be told it was just a batch of dodgy breathers, this looks more like they fell asleep on the job at the design and testing stage .

I am guessing that the European version is a variant of the Asian version and they did not retest it from scratch, probably assuming that it would be fine. It is common for manufacturers to certify one part and then allow variations in design up to a point without full re-testing.

Since the gearbox comes from a 3rd party, it is also possible that they changed the spec and didn't tell MG.

 

[Fogey]

So, is the 'breather' effectively an expansion tank? If it is merely a longer pipe wouldn't some oil still be able to escape or debris to enter?

Not really - an expansion tank is there for a liquid-only system, to allow for dimensional changes with temperature.

The casing in question contains mainly air, with an amount (0.9 litres) of oil present - which is agitated furiously by the gears contained.

The breather should allow free movement of the air in and out, but stop any flow of oil outwards - or any liquid (e.g. puddle water) inwards.

A longer pipe would allow gravity to shift any escaping oil back into the casing. The open end of the pipe would have to be placed in a position which will prevent any likelihood of anything other than air back into the casing - and there lies an interesting question...

 

[tsedge]

Not really - an expansion tank is there for a liquid-only system, to allow for dimensional changes with temperature.

The casing in question contains mainly air, with an amount (0.9 litres) of oil present - which is agitated furiously by the gears contained.

The breather should allow free movement of the air in and out, but stop any flow of oil outwards - or any liquid (e.g. puddle water) inwards.

A longer pipe would allow gravity to shift any escaping oil back into the casing. The open end of the pipe would have to be placed in a position which will prevent any likelihood of anything other than air back into the casing - and there lies an interesting question...

All good stuff, but they are not typically open-ended pipes. This is how one typically looks.

 

[Fogey]

So their answer is to stick a bit of hosepipe on it. Hey, if it works and lets new owners enjoy their cars at last that's fine, just can't quite understand how this design flaw passed their testing, manufacturers usually boast about the millions of miles they cover so this doesn't happen.

Was sure we were going to be told it was just a batch of dodgy breathers, this looks more like they fell asleep on the job at the design and testing stage .

True - though I should imagine there would be pressure to make the breather as short as possible, to allow for a compact, self-contained, installation.

The extended breather may possibly consist of a flexible pipe, whose end is placed, er, somewhere "safe".

 

[Fogey]

All good stuff, but they are not typically open-ended pipes. This is how one typically looks.
View attachment 12131

Yes, but I wasn't meaning anything otherwise - the end is still open to the atmosphere (and anything else).

 

[WalkingBootWeather]

So are we saving that all MG4 owners should have a flexible pipe, (and comfortable slippers)?

 

[tsedge]

Yes, but I wasn't meaning anything otherwise - the end is still open to the atmosphere (and anything else).

I thought you meant that, was just clarifying for others as they might have got the wrong idea.

 

[Fogey]

So are we saving that all MG4 owners should have a flexible pipe, (and comfortable slippers)?

And a top-hat.

 

[Macadoodle]

The open end of the pipe would have to be placed in a position which will prevent any likelihood of anything other than air back into the casing - and there lies an interesting question...

They're gonna drill a hole in the floor of the boot ain't they.

 

[Fogey]

They're gonna drill a hole in the floor of the boot ain't they.

Only if they think their customers are amenable to the whiff of hot oil in the cabin!