The latest vehicle to arrive at my cousin Jim’s shop is this iconic 1989 BMW M3.  For a 20+ year-old vehicle this one is in remarkable shape traveling (according to the odometer) slightly over 80,000 miles.  However, rust has no mercy and is relentless in attacking all sorts of vehicles regardless of their desirability.

The owner of the M3 brought the car to Jim in the hopes of having several rust spots repaired on the roof, in the area ahead of the opening for the sunroof.  In addition, the battery box – located in the trunk of the vehicle – has some rust issues also.

So this is what the roof of he car looks like.

By now you are wondering how would the roof rust in such unusual spot and with such weird pattern.  Turns out, if you zoom in on the picture close enough one can see the slight evidence from where one of those popular 80’s and 90’s sunroof wind deflectors touched the car’s roof.  Looking at the way pattern of rust holes, there must have been some sort of flaw in the way the wind deflector was installed and this caused the paint to wear down to bare metal.  Once that happened, moisture seeped in and the rest is history.  In addition, the area where the rust resides in is close to the sunroof drains.  This must have been packed up with debris at some point in time, and this also contributed to the vast amounts of rust.

Unfortunately, damage is not confined just to the top.

Rust formed on the inside seam of the sunroof as well as on the bottom of the sunroof tray, all located towards the front of the car.  This is going to be a difficult repair, because of the intricate shape and patterns that will need to be made to make the new repair patch panels.

Next, we have the battery box, and this one is indeed interesting!  Here are a few pictures…

As you can see from the pictures above, there is a fair bit of damage.  To make things worse, the owner had cut a piece of plywood and had glued it to the rusty floor. This only trapped moisture even more making things that much worse.  So, how did so much rust accumulate on the floor of the battery box?

These two pictures are from the driver’s side area behind the rear wheel.  This is basically the same place where the battery box is on the passenger’s side.  As you can see, there is a trim piece still in place and it has a rubber hose attached to it.  That is the drain for the sunroof channel.  All sunroofs have at least one.  As advanced as the engineers were that created this “ultimate driving machine”, the completely missed creating a backup plan.  Yes, a backup plan.

If you look very close at the photo on the right (see above), you will see there is water in the floor of that cavity!  So, even with the drainage hose properly attached, there is a place for water to accumulate and what is deplorable:  there is no drainage hole for the water to escape out of.  Very poor design indeed.

And finally, a couple of pictures of the 4 cylinder engine everyone gets a hard-on about…