Hi all, my mother's car, a 1987 300TD with 180K miles has some issues - water leaking into the cabin and electrical shorts. This all started a few weeks ago when we got several inches of rain in a short period. I'm told that water was dripping out of the ignition switch!! I found that the spare tire area in the back was 4 inches deep in water. The drain was plugged.

The battery was a MB 100 amp battery which is about 12 mo. old. Ignition seemed to work, glow plug cycle went through fine. Then just a "click" which came from starter solenoid. Charge on the battery was 12.4v. I switched the MB battery with the battery from my 300E and the car started fine. My battery had about 12.7 or 12.8v. The car started for about 3 days but now is back to "click" on ignition and no start.

I cleaned the battery terminals and I cleaned the battery ground connection.

The starter is a rebuilt Bosch unit which I removed and had tested. It's fine. I'm hoping to get some tips on where to start diagnosing. Tomorrow, I plan on testing the fused circuits to see which, if any, is drawing current. I suppose the alternator could be bad?? How can I test the alternator?

Thanks in advance for any tips/tricks. I'm an avid reader of this site, about every day.

WITH the engine OFF
Using a multimeter interfaced between the positive cable and the positive
battery post ON THE D C VOLTAGE setting ;testing the fuses will tell which
circuit(s) are drawing. From there it's determining which USER is BAD.

If you have a "Hall Effect" clamp for the M.M. ,used on the "AMPS" sequence
you'll be able to tell exactly which USER is drawing too much.

With the engine running place the appropriate test leads on the + and -
battery terminals ... if the reading is between 13.5 and 14.5 volts the ALT
is O.K.

Go to the FLUKE company website , there you will find explicit directions on
how to test the cables in your charging system.

YO, Brother ... H2O leaking from the ignition switch???

I'm backpedaling like mad. Mayhaps best to allow everything to dry out
for an extended time before further assault.?.

Hi again, I've done some further investigating and still cannot solve this no start condition. I took a fresh battery from another car and placed it in the 300TDT. Glow cycle works fine, then "click." It's not the battery, it's not the starter. By using a fresh battery, I've ruled out parasitic drain, right?? Ground connection at starter and at battery are tight and clean. What am I missing? Any suggestions?

Found the problem. Small screw had damaged connector which allowed current to short. Fixed item, put back together and all is well.