MG4 Reduction Gearbox Oil Leak

[Macadoodle]

So the leak is still there but reduced?
Your theory is that it is 'pressured' up your revised pipe and just spitting a little out the end at this stage without any oil gathering in the clear tubing which would be obvious?
Surely your version 2 will solve this otherwise you will have to make it 2 metres long and coil it under the car somehow.

Yep, with the length of the tube increased 3 fold and the end of the tube with the breather attached now well above gearbox level I can only hope this solves it

 

[Macadoodle]

Is this new leak definitely coming out of the breather at the end of the 30 cm tube ?

Yeah, could see traces of it on the little holes in the breather valve. All the other joints seem dry.

 

[AndyL61]

Yeah, could see traces of it on the little holes in the breather valve. All the other joints seem dry.

Ok , like you I can't believe it's managed to make it that far just from oil throw. I'm gobsmacked.

 

[AndyL61]

Do you think that part of the problem is the breather having a one way ball valve which will create a small amount of pressure, then release it quickly. Would it be better to just let the cavity breath to atmosphere unhindered by any valve which would mean no pressure being created ?

 

[Macadoodle]

Do you think that part of the problem is the breather having a one way ball valve which will create a small amount of pressure, then release it quickly. Would it be better to just let the cavity breath to atmosphere unhindered by any valve which would mean no pressure being created ?

Yes that absolutely might be the case, had occurred to me to try it without but was slightly nervous of outside contaminants entering the box.
The ball bearing might be acting like a popping cork and encouraging this oily incontinence.
Not sure if this is a typical design with breathers, never took much of an interest in them in my 30 odd years fiddling with cars !
Surely a breathable piece of foam or whatever on the end would be enough to keep dust out while allowing air to move to and fro .

 

[Hagen]

I take you back to the 17th of October last year:

MG4 Reduction Gearbox Oil Leak

A small update from me. You may have seen in post #228 that oil leak diagnosis has been delayed as the latest software update bricked the car and it can't be switched on. Advice from MG to techs is to disconnect the 12v battery, leave it over the weekend and they "hope" it will rise from the...

www.mgevs.com

If its foam, Shell is doing a bad job. There is 1 client for this pretty new developed transmission fluid I saw: SAIC.

More likely: when pressure is building up in the gearbox, a mixture of fluid and air is rising in the tube. Those 'fluid air bubbles' are leaving the breather after some time. When the fluid in the gearbox is cooling, the ball closes the breather. Massive fluid stays in the tube because the vacuüm. Maybe 'fluid air bubbles' not?

 

[Hagen]

Yes that absolutely might be the case, had occurred to me to try it without but was slightly nervous of outside contaminants entering the box.
The ball bearing might be acting like a popping cork and encouraging this oily incontinence.
Not sure if this is a typical design with breathers, never took much of an interest in them in my 30 odd years fiddling with cars !
Surely a breathable piece of foam or whatever on the end would be enough to keep dust out while allowing air to move to and fro .

My Yanmar diesel also has a one way breather. Thats marine and water is the enemy

 

[Macadoodle]

Massive fluid stays in the tube because the vacuüm. Maybe 'fluid air bubbles' not?

The transparent 30cm extended tube I fitted had no oil residue inside when I looked at it today.
Oil was evident below the little holes in the original tiny breather I fixed to the end of that tube.

So oil is definitely passing the length of my first short pipe, maybe in squirts or foam form, who knows, but I don't think it's getting trapped in a vacuum.

 

[wiz043]

Yep, with the length of the tube increased 3 fold and the end of the tube with the breather attached now well above gearbox level I can only hope this solves it

I can understand you experimenting for a solution to the oil leak issue and I applaud you for it but it is ridiculous that anyone needs to do this with a brand new car under warranty because MG cannot get on top of it.
Many say that the MG4 is a great drivers car and and no doubt it is, and the oil leak and software issues are minor 'quirks' with the car and they can live with that until solutions are found. My view is that the oil leak problem is a couple of steps up from a minor issue.
From reports here it doesn't seem to matter how much oil is in the car as many seem to leak anyway and if owner's accept that for the time being and the oil leaks out to the extent that components fail I wonder whether MG will honour warranties.
This has been going on since last October in the UK to my knowledge and probably months before that in China, plenty of time for MG to sort out 'teething' issues.

 

[tsedge]

Discovered that I still have a small leak today Looks like 12 inches just ain't gonna cut it.
There was no trapped oil in the extended tube I fitted and I simply cant believe simple 'splash' is getting that far up a 30cm 10mm ID pipe.

I think its foaming that is causing the issue, but unless I rig up a go pro underneath the car its not easy to say for sure.
I have devised a version 2. Its around a meter long of the same 10mm clear tubing, comes out of the breather stub I fitted snakes along under the charger DC/DC conv unit at the back of the car, and terminates about half way up behind the rear bumper, capped with the original breather valve.

I am running with the full 900ml of oil but boy this car is a squirter ?

Does sound like it must be oil suspended in air, so foaming most likely. Edit - IIRC Macadoodle already did put different fluid in, possibly then needs to be the official stuff for best comparison test.

I can understand you experimenting for a solution to the oil leak issue and I applaud you for it but it is ridiculous that anyone needs to do this with a brand new car under warranty because MG cannot get on top of it.
Many say that the MG4 is a great drivers car and and no doubt it is, and the oil leak and software issues are minor 'quirks' with the car and they can live with that until solutions are found. My view is that the oil leak problem is a couple of steps up from a minor issue.
From reports here it doesn't seem to matter how much oil is in the car as many seem to leak anyway and if owner's accept that for the time being and the oil leaks out to the extent that components fail I wonder whether MG will honour warranties.
This has been going on since last October in the UK to my knowledge and probably months before that in China, plenty of time for MG to sort out 'teething' issues.

I don't disagree with you, the oil leak problem is something MG need to get better on top of and I think a recall is justified now that we've started to get examples of more serious failures because of an untreated leak. That does put it a couple of step above minor issue territory and MG are shooting themselves in the foot with warranty claims if they don't at least check all cars for the leak.

I am not confident MG fully understand the problem and Macadoodle is to be congratulated for using his expertise to better diagnose.

If its foam, Shell is doing a bad job. There is 1 client for this pretty new developed transmission fluid I saw: SAIC.

More likely: when pressure is building up in the gearbox, a mixture of fluid and air is rising in the tube. Those 'fluid air bubbles' are leaving the breather after some time. When the fluid in the gearbox is cooling, the ball closes the breather. Massive fluid stays in the tube because the vacuüm. Maybe 'fluid air bubbles' not?

Definitely worth trying an alternative fluid, but as you say unlikely to be the issue.

 

[Ian Key]

The transparent 30cm extended tube I fitted had no oil residue inside when I looked at it today.
Oil was evident below the little holes in the original tiny breather I fixed to the end of that tube.

So oil is definitely passing the length of my first short pipe, maybe in squirts or foam form, who knows, but I don't think it's getting trapped in a vacuum.

Would a bigger bore pipe allow the air pushing the oil droplets up the tube slow down the air flow allowing the oil to drop back before reaching the breather valve on the end?

 

[AndyL61]

Yes that absolutely might be the case, had occurred to me to try it without but was slightly nervous of outside contaminants entering the box.
The ball bearing might be acting like a popping cork and encouraging this oily incontinence.
Not sure if this is a typical design with breathers, never took much of an interest in them in my 30 odd years fiddling with cars !
Surely a breathable piece of foam or whatever on the end would be enough to keep dust out while allowing air to move to and fro .

I now think that this breather should not have a one way valve . There is no value in creating pressure which can suddenly be released. The gearbox needs to breath to atmosphere as it warms up and also as it cools down. I didn't think this breather had a ball valve until you pointed it out. So 2 bits of bad design. Position and lack of bafflingly of the breather and a breather which can cause pressure build up.

 

[Deleted member 10041]

I can understand you experimenting for a solution to the oil leak issue and I applaud you for it but it is ridiculous that anyone needs to do this with a brand new car under warranty because MG cannot get on top of it.
Many say that the MG4 is a great drivers car and and no doubt it is, and the oil leak and software issues are minor 'quirks' with the car and they can live with that until solutions are found. My view is that the oil leak problem is a couple of steps up from a minor issue.
From reports here it doesn't seem to matter how much oil is in the car as many seem to leak anyway and if owner's accept that for the time being and the oil leaks out to the extent that components fail I wonder whether MG will honour warranties.
This has been going on since last October in the UK to my knowledge and probably months before that in China, plenty of time for MG to sort out 'teething' issues.

I totally agree, this issue has been played down by most as being minor with no long term impact on components.

There are 2 reports of really dark/black oil being drained from cars, well below the recommended level left in it and containing debris/swarf. This cannot be good for a car that actually shouldn't need this oil changed as part of any service.

Macadoodles efforts are pretty much ruling out oil fling from gears as the cause, I would say, so we are back at poor design/components, 5 months in and this looks to be heading back firmly into MG's hands again for a solution.

The better weather is coming and people might be more tempted to test the speed and handling of their cars in higher temps and as has been said this type of driving certainly seems to be a pre cursor to the leak.

It doest seem to be going away anytime soon which is extremely disappointing for a car that had been on the road from June last year.

 

[Auto Surgeon]

Yes that absolutely might be the case, had occurred to me to try it without but was slightly nervous of outside contaminants entering the box.
The ball bearing might be acting like a popping cork and encouraging this oily incontinence.
Not sure if this is a typical design with breathers, never took much of an interest in them in my 30 odd years fiddling with cars !
Surely a breathable piece of foam or whatever on the end would be enough to keep dust out while allowing air to move to and fro .

You can buy small air filter type breathers that fit on tubes, might be worth a try.

 

[Eber]

My view is that the oil leak problem is a couple of steps up from a minor issue.

Absolutely agree. This is the only issue that would have made me give the car back, but the modified breather works for me. All other problems are more or less software related and hopefully will be fixed soon. But an oil leaking car in 2023 is completely unacceptable. Especially when it's caused by a fundementally flawed design.

 

[Ayoull]

I've submitted a DVSA fault report for the gearbox leaking stating the danger is to myself getting oil on the rear wheels from where the rear undertray ends at the wheels and to other road users.

Might be worth others doing the same, and I've just completed the form stating date of fault was the day I first noticed it leaking.

 

[Macadoodle]

Would a bigger bore pipe allow the air pushing the oil droplets up the tube slow down the air flow allowing the oil to drop back before reaching the breather valve on the end?

The physics would suggest that might work, was thinking of a wide spot in the form of a catch bottle in- line in the tube and vertically mounted.
My latest pipe run does have lots of space in the void behind the rear bumper and is easily accessed if you take off the rearmost undertray .

I now think that this breather should not have a one way valve . There is no value in creating pressure which can suddenly be released. The gearbox needs to breath to atmosphere as it warms up and also as it cools down. I didn't think this breather had a ball valve until you pointed it out. So 2 bits of bad design. Position and lack of bafflingly of the breather and a breather which can cause pressure build up.

Think that about sums it up Andy, some really weird design choices made with this one.
I struggle to see the point of the ball valve, surely you want the air to move unrestricted ? Moisture and dirt are the enemy and a little filter would deal with that.

 

[KDP]

I had the modified breather fitted at the end of January and all seems well at the moment.

My concern is that the volume of oil might have been reduced to minimise the chance of leaking. I could raise the rear of the car and remove the filler bolt and see if the oil level is near the top, but the car really needs to be level to be sure.

 

[AndyL61]

My car came with the modified breather fitted, I've now covered 1k miles with some motorway and faster stretches. All seems dry . I do wonder how much oil is in there but that is MG's decision, as long as it stays dry then as far as I'm concerned I need to stop worrying about it and enjoy the car. I will still keep my eye on it though.

 

[Macadoodle]

My concern is that the volume of oil might have been reduced to minimise the chance of leaking. I could raise the rear of the car and remove the filler bolt and see if the oil level is near the top.

That's another annoying design decision, it doesn't have a level plug, just a drain and a high up filler.

My car came with the modified breather fitted, I've now covered 1k miles with some motorway and faster stretches. All seems dry . I do wonder how much oil is in there but that is MG's decision, as long as it stays dry then as far as I'm concerned I need to stop worrying about it and enjoy the car. I will still keep my eye on it though.

Indeed, its MG's problem if the box seizes. I think the only thing that concerns me is if a low oil level 'just' causes accelerated wear and eventual whining from the tranny.
Are MG just going to claim 'normal wear and tear' when challenged about this in 2 or 3 years time ?
Would be very interested in finding out the amount of oil left in the modded breather gearboxes before they stop leaking. Go on, you know you want to !