Hole in inner arch and unknown connector

[-Ollie-]

Hi Guys,

I have been tinkering with the car this evening and noticed a couple of things. First off is this unknown connector lying underneath my washer bottle, what is this for?





Whilst swapping some wheels over I noticed a small flaky piece of underseal in my d/s front arch. I scraped at it a little and there is a small hole underneath the underseal. Here it is, please excuse the white substance on the inner arch around the hole, it is a rust treatment.



And a couple of pictures to show the location of the whole:




So the question is guys, is this whole supposed to be there and has been painted over with underseal by previous owners?

Thanks a lot.

Ollie

[ShepsEVO3]

Ollie, that hole is not meant to be there.. MANY M3's fail there and get ALOT worse than that.. Sort it now before it gets any worse, luckily it looks very localised, but I've seen cars looking as good as yours under that arch which are actually badly rotten once you remove the sealer!

I have no idea what that connector is, but I'll take a look tomorrow on mine and see what I find ;o)

Paul.

[BMG]

Exactly what I found on my car, there was so many areas of underseal that look fine until you look very closely and find it's just hanging in place covering rust that's all ready well advanced.
Unless you can see an obvious application of underseal or thick paint, chances are it's just normal damage/rot.

There's a few odd wires in the engine bay for options on the car that may not be fitted. Not sure on the wire you show, does everything work ?

[-Ollie-]

Excellent, thanks guys.

Not the greatest news in the world but it was what I was expecting to be honest. What would be the best way to have this sorted then? I am tempted to get all the underseal off the arch now and have a good poke around to see what else I can find.

Would that (and any other) small area need to be cut out and a small plate welded in? Is that a relatively straightforward job?

If you wouldn't mind taking a look at your connector Paul that would be great

Thanks guys.

Ollie

[jht3]

is A/C installed? the only 1-pin connector i know of near that location is the compressor ground. mine is shaped differently, but otherwise is in the same spot and roughly the same wiring gauge

[-Ollie-]

is A/C installed? the only 1-pin connector i know of near that location is the compressor ground. mine is shaped differently, but otherwise is in the same spot and roughly the same wiring gauge

Hi James, No AC on the car.

Are you thinking it could be for the option of AC then?

EDIT - I did think it was strange actually that there was this tiny hole with (literally) rock solid metal surrounding it...

Ollie

[Ironhead]

Man these "budding rust" threads always give me the creeps....

I don't like depending on others to work on the car, but rust is one thing I know I cannot tackle on my own, since I can neither weld, nor spray paint, nor do many other aspects of the job.

Good luck getting it sorted.

[BMG]

First I would check every part of of the bulkhead areas in the wheel arches and in the engine bay - around the fuse box and brake servo are fave spots - for other areas of rust. If you are going to weld a patch in , you really need to pull the carpet as I think there is a bunch of wiring and mounted around that area, so you may as well make sure nothing else needs correcting on the bulkhead while the carpet is out. The area around the bulkhead/floor/sill join is another rust trap as this is where a lot of people jack the car incorretly and break the underseal.

Does the car get damp/mist up in this cold weather ? That's usually a sign water has got in such a hole and is in the foam backing on the carpet.

[JZM3]

In all seriousness, that spot inside the wheel well looks like it is caused by rubbing, I have spots that show where my tire rubs. Is your car lowered? Or has it been at any point in its life?

[Paul D]

I had a hole in the same place on my old car just a lot bigger, it seemed to have been caused by the windscreen leaking and the sound deadening behind the dash getting wet.

[-Ollie-]

Hi Guys,

The car is bone dry inside (carpets + dash out recently to check for rust etc.) and doesn't mist up whatsoever.

It's not heavily lowered (H+R springs) and doesn't catch to my knowledge very often. I will be stripping the rest of the underseal off fairly soon and having a good poke around to see what else is there needing sorting.

Thanks,

Ollie