MG4 Reduction Gearbox Oil Leak

[Macadoodle]

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

It's possible I guess. MG's solution is so short in length maybe the oil can creep along in stages if no external pressure can leak back into the pipe to let it flow back.
Having an open end on one would be the only way to rule that out I suppose.

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?

There's definitely no external hose connections on the gearbox. Coolant could flow through internal channels from the motor I guess but I just think that's a complication they would have avoided for a relatively unstressed transmission.
The motor probably sheds several hundred watts of heat at a cruise if it's around 95% efficient, I doubt the friction in the gearbox comes near that figure in average running.

Helps if it has 900ml of oil though

 

[WigglePig]

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).

Likely more to do with the bore being larger I would think.

 

[Hagen]

The Shell E fluid is especially designed voor EV's, I read. It is supposed to be in the gearbox for 'lifetime' (180.000km?). One thing is very bad for this fluid, forming foam: air. Thatswhy a 'one way' breather is used: air comes out under pressure. When the fluid cooled down, the ball in the bearing shut the breather of from air. There may be some underpressure in the box, I suppose.
The only solid solution for the fluid leak in my opinion is a redesign of the gearbox or some baffle under the breather that prevents the splashed fluid come in the breather.
I can't understand why a longer tube works. Are you sure the breather is placed vertical, so the weight of the ball is closing the breather? The vacuüm should hold the fluid in the tube and building up in each trip seems to me.

Sorry ... Shell developed this E-fluid to prevent air forming foam ...
Still it is a good idea to use a 1 way breather to prevent dust and moisture entering the box.

 

[jumad]

Hi there! Simple question: are there people with no oil leak issues? Or this is a common problem present in absolutely all vehicles?

I'm about to buy an MG4 and I'm full of doubts because of this. Thank a lot

 

[tsedge]

Hi there! Simple question: are there people with no oil leak issues? Or this is a common problem present in absolutely all vehicles?

Our poll indicates half of the people here have seen it but this will be an over representation as people seek out a forum when they have a problem.

MG say it is limited to a few hundred vehicles out of many thousands. But they will only count people who have reported it to their garage and had the dealer confirm.

There could be many people with leaks who don't know / haven't noticed yet.

The fact that MG is on its second or third version of the fix tells us that it is trying to find a solution.

This is a minor issue in as much as it doesn't stop people using the car and doesn't seem to have any side effects (edit: except for those with pristine driveways who need to get the oil scrubbed out).

I am not concerned about it, they will get on top of it sooner or later.

Remember that people here are only speculating about the breather design / gearbox design, none of us have the blueprints and so we can't know for sure what the real issue or solution is.

 

[Hallix73]

Hi there! Simple question: are there people with no oil leak issues? Or this is a common problem present in absolutely all vehicles?

The majority of owners have not had any signs of leakage. My car did and the MG modified breather cured it, however the tech guy reckoned mine was leaking from the threaded joint. Has been driven over 2000 miles and no leakage.

 

[tsedge]

I'm about to buy an MG4 and I'm full of doubts because of this. Thank a lot

Nobody can decide for you but you should be aware that all new cars have issues (look at other forums).

There have been a lot of minor issues with the MG4, but things seem to be improving and the one major safety issue had a fix available within a week.

Experience on these forums says that having a quality dealer who is responsive and looks after you is the most important thing when it comes to addressing any problems.

 

[Hallix73]

Nobody can decide for you but you should be aware that all new cars have issues (look at other forums).

There have been a lot of minor issues with the MG4, but things seem to be improving and the one major safety issue had a fix available within a week.

Experience on these forums says that having a quality dealer who is responsive and looks after you is the most important thing when it comes to addressing any problems.

All that is true, good responsible dealer is the answer. My car is running without any problems now. In fact is a bit boring that I have no faults to winge about!!

 

[Les burrows]

I agree with tsedge and halifax73 above just one other point is you won’t find anything better at the price.
And what problems have been noted will we hope soon, be fully addressed plus not all vehicles have all of the issues reported.
But for the money it’s a very good car for sure.
Les

 

[Macadoodle]

I agree with tsedge and halifax73 above just one other point is you won’t find anything better at the price.
And what problems have been noted will we hope soon, be fully addressed plus not all vehicles have all of the issues reported.
But for the money it’s a very good car for sure.
Les

That's so true. Before the 4 came along all we had were well used Konas and Niros at that sort of money, that's if you could even find one at 26k.
Plus, the 4 is just such a cracking little go kart to drive, still look forward to every journey.
Not every car you can say that about

 

[Deleted member 10041]

I agree with tsedge and halifax73 above just one other point is you won’t find anything better at the price.
And what problems have been noted will we hope soon, be fully addressed plus not all vehicles have all of the issues reported.
But for the money it’s a very good car for sure.
Les

Agree with Les for the money the two SE versions cost, there is nothing else on the market that gets close

 

[jumad]

Thanx a lot for your responses! It's all I wanted to know. I agree with the point of the dealer, it's probably the most differenciating factor in customer's experience.

Knowing this I'll go for it.

 

[stevegus]

The Shell E fluid is especially designed voor EV's, I read. It is supposed to be in the gearbox for 'lifetime' (180.000km?). One thing is very bad for this fluid, forming foam: air. Thatswhy a 'one way' breather is used: air comes out under pressure. When the fluid cooled down, the ball in the bearing shut the breather of from air. There may be some underpressure in the box, I suppose.
The only solid solution for the fluid leak in my opinion is a redesign of the gearbox or some baffle under the breather that prevents the splashed fluid come in the breather.
I can't understand why a longer tube works. Are you sure the breather is placed vertical, so the weight of the ball is closing the breather? The vacuüm should hold the fluid in the tube and building up in each trip seems to me.

Sorry ... Shell developed this E-fluid to prevent air forming foam ...
Still it is a good idea to use a 1 way breather to prevent dust and moisture entering the box.

AFAIK differentials dont have vents typically on an ICE car….and manuals boxes ive worked on are not sealed.

But then neither have a special need for anti foam oil….whats with that I wonder.

 

[WigglePig]

AFAIK differentials dont have vents typically on an ICE car….and manuals boxes ive worked on are not sealed.

But then neither have a special need for anti foam oil….whats with that I wonder.

Lots of diffs do have vents but also others don't.

Anti-foam agents in oil are used to prevent a head of foam on the top of the oil bath since this would fill the top of the case if it were bad enough and then come bubbling out of the vent...it doesn't stop air bubbles in the oil itself but prevents a significant amount of the oil being unavailable due to being held up in a foam.

I had fun a few years back with the gearbox in a VX220 which was a well-know bear for pushing oil out of the vent(s).

 

[Hagen]

Thanx a lot for your responses! It's all I wanted to know. I agree with the point of the dealer, it's probably the most differenciating factor in customer's experience.

Knowing this I'll go for it.

Hi Jumad,
I think the MG4 is a good car for the money. I am driving my second Renault Zoe and want to buy the MG4, but a lot of software issues and 2 hardware problems. Never had that in the Zoe, but Renault started in 2012. My advice: wait by buying the MG4 till those problems are solved.

 

[Macadoodle]

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

 

[Deleted member 10041]

Shouldn't matter how you drive a car it shouldn't leak!

The vast majority of EV owners probably drive their cars pretty sensibly especially when it's colder so a lot of 4 owners might not be experiencing this fault as an issue or to a really noticeable extent.

It definitely seems to manifest itself more after a bit of more exuberant driving.

The bottom line is this should not be happening and certainly not 5 months after the first reports

 

[Alb]

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 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

 

[wiz043]

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

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.

 

[AndyL61]

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

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