E91 owners: corrosion heads up. Look!

[ade and liz flint]

During my fettling of my E91, I found a couple of corrosion issues on the rear tailgate.

The major issue is under the split screen seal, directly under the seal and on a welded joint, image below:-



You can see the location where the wiper arm connects with its drive mechanism behind my thumb to give you the location of the issue I'm highlighting.

This corrosion runs along around 60% of the window width on mine and is a serious concern as it's adjacent to the weld. I'd suggest if you own an E91 and haven't already looked under that seal, you do so as the BMW corrosion warranty will still be valid on original material.

The second less bad, but still a longterm concern, is corrosion behind the numberplate. Sadly, Sytner Notts were really clever and fitted aluminium numberplates to the car, with no foam adhesive pad fitted to separate the aluminium plate from the metal boot. Hence I have galvanic corrosion breaking out, too, and will be taking that up as a part of my warranty claim. I'm fitting acrylic plates anyway, but any of you with aluminium plates, tread carefully, here.

A quick phone call to Sytner yesterday and they suggest a 12 year anti-corrosion cover (I have nothing to tell me if it's 10 or 12, I thought the former, but happy if I'm wrong!) but the Cardiff warranty person isn't in so I'll chase next week for an inspection to be performed. I expect this should all be covered...but, guys, lift your seal, rub off the muck and take a look. My guess is owner #1 parked it outside a fair bit as owner#2 garaged when not in use. I found mine was utterly filthy in that area, and the drain holes either side heavily restricted.

[Broch]

Good spot Ade, just had a look at #114 and mine looks dirty but no corrosion that I can see. I'll need to give it a proper clean though to make sure

Onzie

[Metrics]

Hopefully they'll put a new tailgate on as proximity of the weld will make it very tricky to repair.
Well spotted and a section that probably never gets clean but stays wet for a long time.

[ade and liz flint]

Good spot Ade, just had a look at #114 and mine looks dirty but no corrosion that I can see. I'll need to give it a proper clean though to make sure

Hope it's good, Onzie. I'm intrigued to see if anyone else finds similar ie a type fault or a 1-off. The rest of the car is spotless corrosion-wise and (as I know) extremely well cleaned and maintained during the past 4 years of its life. Under this seal, however, is a place only nerdy saddos like me look.... ...and it was very grubby before I cleaned it out. Moisture trap.

Hopefully they'll put a new tailgate on as proximity of the weld will make it very tricky to repair.
Well spotted and a section that probably never gets clean but stays wet for a long time.

My thoughts too. I know my stuff around welding (and Mrs F knows even more, annoyingly ) so I'll be pushing towards a replace if, as is likely, they agree it's a warranty issue. The width of the welded area which is affected is a concern: one small localised bubbled area wouldn't be quite as worrying, but I fear there will be a lot of corrosion penetrating into the seam, making it tough to remove in totality. The car deserves the best, so I'll be pushing for exactly that.

Yes, I love these areas. I'm a stickler for cleaning and treating hidden areas as well as the obviously seen areas! Nothing evades my gaze

[Charles]

A very helpful post - thank you Ade.

This is somewhere I've never looked at (or even considered) but I've just been out and peeled back the rubber seal on my E46.

Thankfully I only have ingrained dirt and no apparent rust issues.

I think your observation about where the car is kept may be relevant as mine has been almost exclusively garaged overnight for all of its 15+ years.

[ade and liz flint]

I think your observation about where the car is kept may be relevant as mine has been almost exclusively garaged overnight for all of its 15+ years.

Leaves and grime = compost =water retention. Low miles, recently well maintained car (but to be honest, not quite to my weird standards!!) which has an unknown past of storage with owner#1. I lived in high salt areas (still do) for a long time, now, so I know that could be a component too in its historical facts (owner #2 was in a high salt storage area, too), but I always ensured our local high salt issues never affected our car condition where possible hence I've not encountered such bad corrosion on such a young car.

It's also bizarre that my full and very thorough survey has found little other corrosion on ANYTHING, even unprotected parts such as boot strut ball knuckles. This is a very localised issue on my car, it appears.

To those that don't 'get' the 'high salt area' comments: coastal.

[ade and liz flint]

A little update: this is going in for inspection at the Sytner Cardiff bodyshop on Weds pm this week. I'll post up any 'interesting comments' to help any other owners who may have the same issue with theirs

[ade and liz flint]

Had this assessed today at Cardiff and their recommendation to BMW is for a new hatch as it's seriously corroded into the welded seam. Part is original and paint thickness within normal tolerances. I'm to expect a decision within 2 working weeks and work has to be done and invoiced to BMW within 21 days of that: quite tight!

I asked if this was common; yes it is, but not normally as serious as this has become, so it's a bit of an extreme.

[simon13]

dont' look underneath then!

E90's have no underseal from factory. Just E plate coating and seam sealer. All the axles can rust badly and the plastic covers can hide sins!

[ali]

Good spot Ade Will need to check my E91 330D to see if it suffers the same

[ade and liz flint]

dont' look underneath then!

E90's have no underseal from factory. Just E plate coating and seam sealer. All the axles can rust badly and the plastic covers can hide sins!

I have and it's actually bloody spotless Hence this one area of corrosion is quite bizarre. Lucky BMW gave 12 years anti-corrosion....for us, not them.

Agree on the plastic covers; any car with those is desperately hiding secrets. Mot advisories on cars fitted with plastic undertrays are common: I have it on #127's past few mot certs. Given time I'll have them off for a peek beneath.

[ade and liz flint]

Good spot Ade Will need to check my E91 330D to see if it suffers the same

It's awkward to lift the seal, so get a blunt plastic tool to just ease a piece of seal up so you can get your fingers under and move along the seal to visually inspect the whole length of that seam weld. We were like contortionists at Sytner, with me holding up the seal and trying to be out of shot as he leant in and photographed it all.

It's actually worse than I initially thought too: just creeping up onto the visible bodywork in one spot, and a few blisters further along from the pix I put above have ruptured and are 'bleeding'.

[ade and liz flint]

Some pics from under #127 today with the differential removed:-







Pretty damned happy with this. Very clean indeed, and little corrosion other than the areas I'd expect to see a little. Makes the window issue even stranger....

[Bob]

Really does look clean under there, so strange how it can have such bad, localised corrosion on the tailgate.

[ade and liz flint]

Really does look clean under there, so strange how it can have such bad, localised corrosion on the tailgate.

I think we have a bit of an E91 weakness with the welded seam, and #127 has dropped unlucky for some reason and really blown badly. Otherwise, as said so many times: such a 'clean' car. Corrosion on the diff flanges I'd expect, a touch around the exhaust (again: expect) but elsewhere is like a year old car.

I didn't photograph as not really very interesting, but the front wheel enclosed areas are similarly untarnished by the dreaded corrosion.