Ratty E39 530i Winter Beater Project

Alright, a few minor updates. My $10 airbag side impact sensor showed up in the mail. I disconnected the battery, plugged it in, reconnected the battery, and cleared the airbag module codes. You can see how bad the old one looked:

While a whole bunch of codes came up for having the seats and seatbelt pretensioners disconnected, the left side impact sensor communication fault was gone so I'm assuming the SRS light will turn off once the car is reassembled. Victory! 

I also investigated the ambient air temp sensor a little bit. The sensor itself seems to be working; I measured resistance across its terminals and it changes under a heat gun. I think that something is screwy in the wiring...which should surprise exactly nobody at this point. I'll have to pull out the instrument cluster to diagnose further. 

I'm gonna hit the junkyard again and hopefully pick up a new ABS module and some trim pieces. Being a Florida car, the sun burned off most the clear coat and pretty much ruined most exposed interior trim.

That could be used as a good "trunk monkey" door.......

Got a little bit more done last night. A $15 yaw sensor from Ebay arrived. I plugged it in and it seems to be reading properly:

You can see the old one was also in pretty bad shape as it went for a swim:

Hopefully that cures the yaw sensor fault that is reading from the ABS module. The only other fault it is logging is the RF wheel speed sensor. However, given that I learned the brake light circuit is internally shorted in the ABS module, I'm working under the assumption that the module itself is bad. I did find a spare module at the UPick. It's the same model year but the car it came from was beyond rough so we'll see if it works. I need to figure out how to reflash it for my car but it doesn't seem too difficult.

At the junkyard, I found a new parcel shelf and some other trim. You can see the original parcel shelf was faded into oblivion:

I'm debating returning and grabbing the rear seat from the junkyard but it's $40. The headrests on this one are starting to flake and there is some fading in the seat back. I put things together just to see how the new trim looks:

Definitely an improvement. I think I will probably pick up the other seat. I would like the interior to be a decently nice place to hang out even if the exterior is rough as hell. 

I did grab an ambient temp sensor and whaddayaknow it fixed the -40F problem. I guess even though the thermistor in the original one seemed to be working it was out of the expected range. Easy enough to fix and free! 

So, not a ton of progress yesterday but at least it's still moving forward. 

A few updates on this project. I've been sort of distracted by the return of this project from paint:

Anyway, on to ratty Bavarian crap:

I did get the interior back in the car and 90% finished. Most of the trim I replaced with pieces pulled from the junkyard that are in much better condition. I still need the wood trim for the center console as I can't find a decent one. You can see how dirty the carpet was:

An example of the new(ish) vs old trim:

Also in ultimate cheapskate repairs there were a couple of instances of this:

I also pulled the tape off the sunroof and checked for leaks. Turns out the drains and seals were working properly. Water was getting in the car through the firewall. Some panel removal and leaf clearing led me to this hole as the culprit:

That 15 mm hole let in a surprising amount of water! Glad I tested the car with judicious use of the garden hose before reassembling all the interior. 

One other sort of fun mini-project was getting the key fobs working. I had two keys but neither did much other than start the car and manually open locks. I cut the case apart using a razor blade and tested the battery:

As you can see, it's less than ideal even unloaded. Apparently these batteries recharge when in the ignition but considering they were from 2001, it's no surprise they had gone flat. You can buy Chinese-special replacements but they need to be soldered in. Here's the PCB, old battery, and replacement:

Soldering the new battery in is pretty easy. The two large contacts you see here are the posts and there's plenty of room around them:

I tested them out...and nada. However, after checking and replacing a fuse and reinitializing both keys, they work flawlessly! Another (nearly) free fix! 

So...still a lot to do but I'm not really in a rush to finish it. I think I have like $50 total invested so far which is pretty neat. 

Jeez, this thread gives me the sweats (former 540i owner).  If my E39 had that many electrical faults, I'd probably just short the wrong thing to ground and walk away from the ensuing blaze.

Also, be careful with powering on the car with SRS system components unplugged. From what I remember, the car REALLY dislikes this and sometimes requires a dealer visit to reset everything.

In reply to sobe_death :

Yup, it gets really bent out of shape about having power with seats, airbags, etc. disconnected. It also doesn't help that the battery is on its last leg at around 9V or so. It's easy enough to reset the SRS codes on my own so I'm not too worried about it. 

Alright, I've been distracted by the 986 project but as we had an early snowpocalypse it's time to finish the winter beater. I've been putting off doing the mechanical work because that isn't much fun when it's below freezing in the garage. 

First order of business, clear the snow off the car and chip away enough ice to be able to find the lift points again (have I mentioned I hate winter in MI?)

This is the ice chipped away to reveal a single lift pad:

It's the Boxter's turn to turn into a snow mound:

Winter wrenching is the worst. Took about an hour to get to this point:

Ok, first order of business was to fix the right rear suspension. The wheel had some dynamically variable toe. Like a lot. The ball joint on what BMW calls the guiding link had failed. It's actually fairly simple to replace...just mark the position of the eccentric bolt, remove the arm, and replace. Of course I overcomplicated things by shearing the bolt. BMW dealership had one in stock locally (seems common enough to break them) but that set me back a day and $10. 

Reinstall and pay attention to torque specs this time. Now, onto more difficult things.

Everything else on that corner seemed to be working but the boots for the lower ball joint and sway bar end link were cracked. The ball joint was a little more involved but not too bad.

You basically just unbolt everything and let the control arm hang:

Now you have good access to the ball joint. This one came out with just a basic ball joint tool and a mini sledge:

Press the new one in:

...and wrestle with a bunch of different suspension mounting points to reassemble. Replacing the integral link (pictured below) is a no-brainer as a quality Lemforder unit is uber cheap. You can also see how bad the end link was:

I also ended up replacing the LH guiding link and all other end links because the boots looked worn. 

Next order of business was the brakes. The pads looked new-ish, rotors were good, but all four hoses looked pretty awful:

This was easy enough. Basically soak everything in penetrating oil and carefully remove the old hoses. I always find new brake hoses to be a satisfying job (though messy)

My awesome wife then assisted me in bleeding the brakes...it was around 10 pm and below freezing at that point. She's the best...but I may be getting a power bleeder for Christmas. 

The fluid was super nasty; it was nearly black and definitely had some water contamination. A bottle or two of brake fluid later things looked great on all four corners.

So what now?

I'm not sure. On it's current tires and open diff, this car is terrible on the ice. I think I will register it and maybe put some cheap used snow tires on if I can find some. Although, this morning on the freeway I saw somebody ripping around in a Boxter and I now want that in my life. This car may get sold to make way for the 986 so if you happen to be interested in a fairly solid manual E39, let me know! 

I love reading threads like this.  Cool car, hope you're able to flip it to fund your other projects. 

tip said:

I love reading threads like this.  Cool car, hope you're able to flip it to fund your other projects. 

My other projects tend to fund my race car project. (Or that's how I validate all this nonsense.) This should be a sort-of-fun to drive winter beater that I hopefully won't lose money on (if I ignore my time!)