MG4 Rusting already.

[Macadoodle]

Picked up a stone chip around 10 days ago, sounded like a heavy hit to the top of the windscreen, upon closer inspection it turned out to be on the edge of the roof panel.
Meant to put a blob of paint on it but the weather didn't really allow, looked at it this morning and it's red with rust already, clearly the roof is not galvanized.
Makes you wonder just what is zinc coated steel on this car.View attachment 14920View attachment 14920

 

[Ayoull]

Picked up a stone chip around 10 days ago, sounded like a heavy hit to the top of the windscreen, upon closer inspection it turned out to be on the edge of the roof panel.
Meant to put a blob of paint on it but the weather didn't really allow, looked at it this morning and it's red with rust already, clearly the roof is not galvanized.
Makes you wonder just what is zinc coated steel on this car.View attachment 14920View attachment 14920

Your pictures don't appear to have attached

 

[Deleted member 9692]

Picked up a stone chip around 10 days ago, sounded like a heavy hit to the top of the windscreen, upon closer inspection it turned out to be on the edge of the roof panel.
Meant to put a blob of paint on it but the weather didn't really allow, looked at it this morning and it's red with rust already, clearly the roof is not galvanized.
Makes you wonder just what is zinc coated steel on this car.View attachment 14920View attachment 14920

We can’t see your picture. Do you know if warranty covers this in any way, obviously doesn’t cover stone chips but shouldnt rust surely?

 

[Macadoodle]

I'm just going to treat with phosphoric acid and then blob some top coat on.
On my last car I could just ignore stone chips till I had the time to treat, the zinc underneath the paint was quite obvious. Not so here

I've noticed some paint has flaked from the very bottom edge of the passenger sill as well, it does seem to be galvanised , relieved that the reassuring grey of a zinc coating is present there at least.

 

[Macadoodle]

Well, had a look at the bottom edge of the drivers side sill this evening and there's rusting starting there too, along the line of spot welds.
We get a lot of salting on the roads here but this is the vehicle's first winter for gawds sake
Luckily my car is black so I'm going to spray black waxoyl underbody stuff sparingly along both sills at the weekend.
The rest of the underneath is pretty well shielded by plastic trays so I think that escapes the worst of the salt thankfully.

 

[Ian Key]

I haven't had a chance to look properly underneath mine, apart to check the undertray, so it sounds like a job for Sunday when the rain stops.

 

[Macadoodle]

Yep, might be worth a look to nip it in the bud now. I thought the sills at least looked galvanised but I'm not sure they are having seen this corrosion.
They're coated in factory underseal on the inner surface by the battery, but left in bare primer on the outer surface for some reason.
I always keep an eye on sills on any car, I find that the apes in the typical tyre fitting emporium use jacks with steel cups and wreck the protection in short order.

 

[tsedge]

Yep, might be worth a look to nip it in the bud now. I thought the sills at least looked galvanised but I'm not sure they are having seen this corrosion.
They're coated in factory underseal on the inner surface by the battery, but left in bare primer on the outer surface for some reason.

Missed a step on the production line perchance?

I always keep an eye on sills on any car, I find that the apes in the typical tyre fitting emporium use jacks with steel cups and wreck the protection in short order.

Yes, so many cars get jack damage through this and wrong jacking points. With the weight of EVs, even more likely.

 

[jonney]

Yes, so many cars get jack damage through this and wrong jacking points. With the weight of EVs, even more likely.

What's the mitigation for this?
Getting dealership for tyres or just treating the damage after they scuff them?

 

[Macadoodle]

What's the mitigation for this?
Getting dealership for tyres or just treating the damage after they scuff them?

In the past I've actually taken a pair of wheels off my car and thrown them in the back of my wife's to run them round to the tyre place local to me.
Between the sill damage and over tightening the nuts / studs I'd rather do the fitting myself

 

[tsedge]

What's the mitigation for this?
Getting dealership for tyres or just treating the damage after they scuff them?

Use a garage that cares.

 

[jonney]

Use a garage that cares.

Where the hell do you find that?

 

[Deleted member 10041]

Not a good sign that it's showing rust after one winter

 

[OriginalBigAl]

Yep, might be worth a look to nip it in the bud now. I thought the sills at least looked galvanised but I'm not sure they are having seen this corrosion.
They're coated in factory underseal on the inner surface by the battery, but left in bare primer on the outer surface for some reason.
I always keep an eye on sills on any car, I find that the apes in the typical tyre fitting emporium use jacks with steel cups and wreck the protection in short order.

Saw a video (youtube ) on MG production line which looks like there are electo galvanised panels which are put together and spot welded robotically , the heat from the spot welds will burn off the thin layer of zinc leaving those spots unprotected apart from any subsequent paint finishes.

 

[stevegus]

Saw a video (youtube ) on MG production line which looks like there are electo galvanised panels which are put together and spot welded robotically , the heat from the spot welds will burn off the thin layer of zinc leaving those spots unprotected apart from any subsequent paint finishes.

That sounds pretty standard

 

[Macadoodle]

Not a good sign that it's showing rust after one winter

No, the corrosion protection seems patchy, bit of an afterthought from what I've found so far

Saw a video (youtube ) on MG production line which looks like there are electo galvanised panels which are put together and spot welded robotically , the heat from the spot welds will burn off the thin layer of zinc leaving those spots unprotected apart from any subsequent paint finishes.

The rust seemed to be forming between the spot welds, strangely The passenger side sill seems fine so far, no rust even where the paper thin paint has flaked a little at the edge, maybe it is zinc I'm looking at.
Anyhoo, I've had excellent results with the waxoyl underbody stuff, never fully sets hard so wont peel and trap moisture but is tough enough to stay put. Big can from Halfords is only £6.