MG4 Reduction Gearbox Oil Leak

Update on engineer report been out over weekend car is now in for rejection.engineer said he is fed up off visiting mg cars for rejection.oil leak is worse than original breather pipe has failed car covered underneath I will upload the report when I receive it with his comments
Just to add to it also the seals on the boot have also failed boot is drenched with water inside not used car for 6 weeks due oil leak engineer was shocked amount water inside

My 6 week old 1100 mile dec build car has absolutely no leak and the underside is also flat with no kinks

stevegus said:

My 6 week old 1100 mile dec build car has absolutely no leak and the underside is also flat with no kinks

Click to expand...

I heard the new batch builds have been redesigned but how true this is I don’t know.the first batch seem to be the vehicles giving the issues

Mars6394 said:

I heard the new batch builds have been redesigned but how true this is I don’t know.the first batch seem to be the vehicles giving the issues

Click to expand...

Be interesting to know if the new 'design' just involved putting less oil in the reduction gearbox.
We are all waiting with baited breath to hear from someone who has drained the oil to check ml. content in the later models without leaks.
In fairness the later models may have a completely new designed breather or whatever but if they have just dropped the oil content from the recommended 900ml to 600 or 700ml as a bandaid fix then that's a deal breaker for me and they can forget about me as a future customer in Australia.

wiz043 said:

We are all waiting with baited breath to hear from someone who has drained the oil to check ml. content in the later models without leaks.

Click to expand...

Whos going to that level of hassle tho on their less than a year old car?

stevegus said:

Whos going to that level of hassle tho on their less than a year old car?

Click to expand...

A couple of members here indicated some time back that they would be draining the oil to check the content at some stage on their leak free cars as they were concerned that the oil content may have been reduced possibly creating other issues down the track.

Of course these cars are under warranty but I doubt anyone wants to have to make a claim on a wrecked reduction gearbox at some stage in the future which may or may not occur of course due to lower oil levels than recommended.

wiz043 said:

Be interesting to know if the new 'design' just involved putting less oil in the reduction gearbox.
We are all waiting with baited breath to hear from someone who has drained the oil to check ml. content in the later models without leaks.
In fairness the later models may have a completely new designed breather or whatever but if they have just dropped the oil content from the recommended 900ml to 600 or 700ml as a bandaid fix then that's a deal breaker for me and they can forget about me as a future customer in Australia.

Click to expand...

That's assuming that 900ml was correct in the first place.

Many years ago I had an Austin Maxi which when filled with oil to the correct level on the dipstick would blow the oil into the clutch housing and contaminate the clutch requiring it to be replaced. Someone had made a mistake in the required oil level and susiquently the markings on the dipstick. The official solution was to lengthen the dipstick so lowering the fill mark so less oil was put in which stopped the problem. Never had a problem with the clutch after the fix and never had a problem with the engine either.

Ian Key said:

That's assuming that 900ml was correct in the first place.

Click to expand...

Well if it wasn't correct what are the so called engineers doing designing reduction gearboxes?
Maybe they would be more suited to a less complicated profession.

A friend of mine took delivery of a Standard SE model in Luxemburg on the 10th of May. It seems to have the modified breather and still leaks oil. He will visit his dealer tomorrow. It's still a thrill.

Be interesting to know the build date.

wiz043 said:

Be interesting to know if the new 'design' just involved putting less oil in the reduction gearbox.
We are all waiting with baited breath to hear from someone who has drained the oil to check ml. content in the later models without leaks.
In fairness the later models may have a completely new designed breather or whatever but if they have just dropped the oil content from the recommended 900ml to 600 or 700ml as a bandaid fix then that's a deal breaker for me and they can forget about me as a future customer in Australia.

Click to expand...

Absolutely, they don't deserve your dollars if they don't do the right thing with this flawed design.

The most oil this box seems to be able to contain is 650ml, even with their stick on periscope fitted.
If that is what the newer batches of cars are operating with then in my humble opinion it's simply not enough. I'd be shocked if there's another EV on sale running with this tiny amount of oil in its gearset .

I wrote way back in this thread somewhere, when who ever designed the box decided at that time that 900 ml was required so anything less is incorrect.
Les.

as you are aware mine is now rejected.but the response back from mg was to retry a new breather again I have refused as this issue does not seem to be resolving at all anytime soon.and now new build cars are the same issue it’s shocking the customer service has been awful hope everyone gets sorted but the oil level would be great to know

Mars6394 said:

as you are aware mine is now rejected.but the response back from mg was to retry a new breather again I have refused as this issue does not seem to be resolving at all anytime soon.and now new build cars are the same issue it’s shocking the customer service has been awful hope everyone gets sorted but the oil level would be great to know

Click to expand...

Well, as they say...'the proof will be in the pudding'.
If MG4 reduction gearboxes start to fail down the track and it is proven that the reason was that the oil content was not sufficient MG will have a lot of explaining to do.

Perhaps they have confused the term 'preventative maintenance' with 'bandaid fix' if they have gone down the track of reducing the oil level.

As many know it is not really about the breather design but more about where it is attached and regardless of how long they make the 'spout' oil still seems to fly out with reduction gears turning at speed with the correct oil fill.
We are all aware our enterprising friend here @Macadoodle devised the solution by placing a sensible breather in a different position on the 'box (in simple terms).

It appears obvious that the 'box was designed to hold 900ml of oil as Les indicated in #3,212 and many still leak with the 'modified' breather anyway but what is puzzling is that not all cars have the issue but what we do not know is whether the 'fix' for those and the latest models is just to reduce the oil content.

This is going to be a problem for MG sales down the track in my view as there is now at least one comparitively recent video on the 'net showing prospective buyers where to look for possible oil leaks, and a bulging tray under the car and other quality control issues prior to purchase....fine for a used car but discouraging when you are shopping for a reliable new car.

Can't they just block the breather off, does it really need one ?
It's not like an ICE engine breather where the pistons create a significant back pressure that can blow seals.
As I understand it, it's only expansion from heat that creates any pressure in there.
My ZS transfer box breather is blanked off. Some are not.

Kithmo said:

Can't they just block the breather off, does it really need one ?
It's not like an ICE engine breather where the pistons create a significant back pressure that can blow seals.
As I understand it, it's only expansion from heat that creates any pressure in there.
My ZS transfer box breather is blanked off. Some are not.

Click to expand...

The idea is that there's no pressure build up at all , the only way to achieve that is to allow the cavity to breathe in both directions. That's why I couldn't understand why they would fit a one way ball valve in the original breather. They actually caused a build up then sudden release which will spit oil out as well as putting it in line with the main crown gear. So it became a double effect of allowing pressure to build and fitting the breather in the worst position. Just wrong, bad design.

Update: the dealership was aware of the oil leak issue but did not have a car with it so far. There is a revised version of the modified breather consisting of three separate parts - it is on back order.

It's really strange why some cars have this issue and some don't. They did not provide any information on the oil level, but my friend will try to have the new breather shown to him.

Eber said:

Update: the dealership was aware of the oil leak issue but did not have a car with it so far. There is a revised version of the modified breather consisting of three separate parts - it is on back order.

It's really strange why some cars have this issue and some don't. They did not provide any information on the oil level, but my friend will try to have the new breather shown to him.

Click to expand...

Revised version of a revised version which still fails did on mine anyway unless there has been another revision version 4. good luck.they will underfill and send you on your way seems to be the fix

I think it will remain a mystery until someone external with gearbox design expertise tears down the gearbox and gives us an independent explanation.

tsedge said:

I think it will remain a mystery until someone external with gearbox design expertise tears down the gearbox and gives us an independent explanation.

Click to expand...

Well Tom I don’t see that happing until one fails to be honest.
Les