Rust Issues

[Alb]

John Cadogan did a good piece on this:

 

[Buster72]

It applies to just about everything, if we start to reject Chinese made cars due to fears regarding rust we may as well reject everything we use on a daily basis including TV's, washing machines, toasters, mobile phones, dishwashers, computers etc.
Just about everything is made in China these days or if assembled in other countries the components come from China.
Even many foods we get from supermarkets come from China even though we are able to produce the equivalent in our respective countries.
It all comes down to price sadly even though we are encouraged to buy food products produced in our own countries whether it be the UK, Australia, US or wherever.

Exactly. This post really ought to read Potential Rust...... because no one has yet identified any areas of rust.

 

[Deleted member 10041]

To be fair areas of concern have been identified as potential week points in the 4 regarding rust

 

[tsedge]

To be fair areas of concern have been identified as potential week points in the 4 regarding rust

I am fairly sure they have skimped on rust prevention. The whole car is built to a low cost and they'll have identified areas that need protection and those that don't, rather than doing the whole thing. If they got the balance right, great, but if not...

Whether this is a significant problem or not, time will tell, in the meantime regular cleaning and protective treatments of the underbody area could eliminate a lot of the risk.

No indeed, we "shouldn't have to do this on a £30k car etc..." but people can choose to ignore it until/in case it becomes a problem, depend on the dealer to sort if it does or be proactive. Those are the choices.

 

[Macadoodle]

The only places I've spotted actual rust are on subframe joints and a stone chip on the roof, but the car is only 10 weeks old.
Wonder if those 1980's plastic body panels on the doors and sills will trap wet mud like they did on hot hatches back in the day.
SAIC have been selling MG badged cars for well over 10 yrs have they not ? Anyone know how their earlier cars are doing corrosion wise ?
Their ICE cars are pretty awful and I never paid any attention to them TBH.

I am fairly sure they have skimped on rust prevention. The whole car is built to a low cost and they'll have identified areas that need protection and those that don't, rather than doing the whole thing. If they got the balance right, great, but if not...

Whether this is a significant problem or not, time will tell, in the meantime regular cleaning and protective treatments of the underbody area could eliminate a lot of the risk.

The penny counting seems to start at the body panel pressing stage. They'll buy in rolls of steel either bare or hot dipped in zinc, the former being cheaper.
The lower spot welded edge of the sills on mine have lost some paint and have a reassuring zinc colour showing through and no rust forming.
The big stone chip I picked up on the roof rusted like hell .

What the protection status is of the panels in between is anybody's guess but with the state of the roads, paint chips a plenty will soon let us know I guess.

 

[emmrecs]

@Macadoodle

SAIC have been selling MG badged cars for well over 10 yrs have they not ? Anyone know how their earlier cars are doing corrosion wise ?
Their ICE cars are pretty awful and I never paid any attention to them TBH.

Before buying my MG5 I had a diesel MG6, bought brand new September 2015. When I bought my MG5 my wife sold her (ex-motability) MG3 and took over the MG6. She later sold it (to replace it with a new MG3).

For both "sold" cars (my wife's original MG3 and then the MG6) there was no problem with detectable rust; even paint chips were not rusted through. Based on my experience I cannot say that ICE MG cars exhibited any greater "rust problem" than those of any other manufacturer!

 

[KevW]

Why are you concerned about rust on a BYD? VW had huge problems with rust on the inner wings of the Golf Mk7 but that really isn't a consideration when buying something else!

 

[Christian]

Does anyone actually own an mg4 and has proof of rusting underneath the car?

 

[Deleted member 9909]

Do you mean other than from post #45?

 

[Tig170]

lets wait n see - my previous cars are VAG - never had an issue with rust (in 20 years) - however as I may have noted previously (lets not get on to your 1st car again) my 1st car was an 'MG', an austin allegro - it had more rust holes than a sieve - so far my 6000 mile MG4 (not washed yet), is looking rather good - even the brake discs are still rust free (and better still my car lives under a tree - and bird droppings so far have not damaged it), I'll no doubt find issues when it gets cleaned.

 

[Tig170]

The standard waranty isn't really 7 years : - https://www.mg.co.uk/sites/default/files/2021-10/MG_Online_Warranty_Statement_October_2021.pdf

 

[dicky ticker Dave]

Before we decide on an MG4 we ask if I could have a look at one of our neighbours MG3 on a 63 plate car could find no rust on the body the underside was as a car this age you would expect so we are not too concerned.

 

[OriginalBigAl]

According to the repair manual,(MG4 unless its generic ) the steel used is zinc coated , not hot galvanised as that hardens the steel making it more resistant to pressing , but cold electroplated (zintec) . As in all things this can be in various qualities and thickness of coating. This is easier to paint and smoother than hot galv but not as corrosion resistant. Spot welds will burn off the zinc both in the weld and for a small surrounding area around the weld. After the chassis is produced and ready for painting it is chemically washed and fully emerged in a zinc paint which is electrically charged so it is attracted to the metal and produces a smooth even coating . Robotic arms then apply sealants to joints and seams with manual application to the areas not reachable by the robots. Robotic paint sprayers then apply the primer and top coats ( paint and lacquer) and the whole lot goes into an oven to bake the finish. Then it would be automatically and visually inspected.
This is now pretty much the industry standard but each manufacturer can decide the quality of the original materials and thicknesses and standard of paint finishes. Not all fixtures and fittings will go through this process, only the ones fitted to a bare chassis so some added on parts could be less protected than the main chassis.
The inner sills and other concealed hard to reach areas have a thin protective ( oil/wax ??? ) coating manually sprayed inside via access holes before being covered by the plastic trims , wheel arch covers.
Quite impressive when compared to cars of previous years although my previous 19 year old Peugeot did have a hot dipped galv chassis ( more expensive process ) and even though some paint had come off to "bare" metal, no rust whatsoever. This could be recognised by seeing the large grain structures of zinc. Zintec is a smooth satin grey grain free coating on the steel.
If you can see down to metal in stone chips etc, then this could be the either of the two "galv" layers which in theory should give a bit of cathodic protection against corrosion but neither will be as good as a fully hot galvanised chassis.

 

[Macadoodle]

My 4 has seen 3 Highland winters now, fair amount of driving on salted roads and very few washes during those winter months - not worth bothering with a black car

Gave it a decent wash on Saturday, jetted behind the arch liners and along the length of the sills, all looks fine TBH.

The very thin layer of paint has flaked off the underside of the sills in various places but the zinc coating is looking fine, puffed a little clear waxoyl over the bottom of the sill just to help it out a little.

The only area I saw rusting quickly was a stone chip on the leading edge of the roof when the car was still practically new, so that panel definitely ain't galvanised, paint seems to be unusually thin on this car IMO.

Overall though, nothing to report regarding body corrosion, I think this car should have an easy 15 year plus lifespan if you hose out the underside occasionally and touch in any rock chips as they occur.
One thing I would add that I think I've mentioned on this site previously - the front subframe where the track control arm bolts locate in recessed 'cups' which trap water throughout the winter, needs attention.

They had a huge amount of surface rust forming after the first winter and if left indefinitely would lead to the subframe rusting through at this point, potentially very dangerous and definitely an MOT failure.
I simply cleared all the accumulated grit and water from the recesses and flooded them with clear waxoyl, grease would probably work fine though.