Aaron K limitedslip.net

19Mar/130

Jumpy gauges no more

Much like my e30 m30, the needles on the gauges jumped all around. When running, you could tap on the speedo and the rpms would jump up. The gas guage seemed to only show either full or empty. This is a typical problem with BMW guage clusters from this era. It is usually either a set of batteries leaking and corroding circuit boards, and/or cold solder joints. Kind of an annoyance, but the real bothersome piece was not knowing if the temperature guage could be trusted.

So I yanked the cluster out and completely disassembled it. The batteries were in decent shape, but they were replaced and relocated external to the cluster. Found a whole row of bad solder joints - check out the pictures below.

guage_cluster
Back side of the cluster. The illumination light bulbs (2 at the top) were pretty dim, so they were replaced with slightly brighter units (+2W approx).
Back side of the cluster. The illumination light bulbs (2 at the top) were pretty dim, so they were replaced with slightly brighter units (+2W approx).
Someone covered the service indicator lights with electrical tape.
Someone covered the service indicator lights with electrical tape.
Removed the electrical tape, but it'd been on there so long the residue remains.
Removed the electrical tape, but it'd been on there so long the residue remains.
1
1
The new batteries and leads off the circuit board. The batteries didn't appear to be in series, so I ran leads for both.
The new batteries and leads off the circuit board. The batteries didn't appear to be in series, so I ran leads for both.
Unlikely need to change these often, but I did put in a disconnect for that purpose.
Unlikely need to change these often, but I did put in a disconnect for that purpose.
Closeup of the bad solder joints. All joints were reflowed on the board.
Closeup of the bad solder joints. All joints were reflowed on the board.
The service indicator board, if I'm not mistaken, and the batteries that are prone to leaking.
The service indicator board, if I'm not mistaken, and the batteries that are prone to leaking.
 


Filed under: BMW 633 CSi No Comments
19Mar/130

Smoked out

After spending an hour scrubbing off the moss on the outside, fixing the gauge cluster, and trying to clean the dash I decided it was time for a freeway speed test to see how highway worthy the car was. I was considering taking it to an autocross; not to race, but just for the road trip.

P1020063

Got it out on the freeway towards the end of the day, it was threatening rain and starting to get dark, but I wasn't going to be out for long anyway. Felt fine at 30-40 mph, but developed a pretty nasty shimmy over 50-60. As I understand it, bad front suspension bushings on this car are the likely suspect. Between that and a bad rear subframe bushing that clunks on/off load, I decided that was the last time it sees those speeds until I get the suspension fixed on it.

On the way back in I noticed a burning smell... didn't think much of it at first, but it progressively got worse. The combination of smoke filling the cabin, the windshield starting to fog up and the rain obscuring everything came on pretty quick to the point where I had to pull it over and get out of the car. Running through my head was the possibility I screwed something up in the dash and that the dash was about to be on fire. When I first bought the car I had the foresight to buy a fire extinguisher for it, but thankfully it never came to that!

After airing the car out and limping it home in the rain with the windows open (smoke was still coming in, but from who knows where), I'm able to get it back in the garage. Figuring putting a smoking car in a garage full of bikes and tools is not a wise idea , I start poking around to find the problem to make sure it doesn't set everything on fire. Smoke was still coming from the hood vents. Turns out in cleaning the dash I turned the blower speed all the way up, and the fan blower motor was seized. Somehow no fuses were blown, but it was dumping enough current into the blower to start melting the plastics, pushing all the smoke into the cabin.

P1020083

Deciding I didn't want to see this happen again, I opted for a new fan instead of a junk yard find.

 

Filed under: BMW 633 CSi No Comments