Hello r3vers. Sorry this post is so long. I'm stumped on a charging issue with my '88 320i Touring, and am hoping the collective r3v wisdom can help. I searched the archives and read threads for over an hour last night, but could not find the exact problem. Most of them are "not charging" threads, but my car seems to be charging but the charging system can't handle a full electrical load. Here's the deal.
Driving home after dark a few weeks ago, I noticed the interior lights getting dim and A/C fan getting slower at stop lights. When I got home and stopped in the driveway, the interior lights got progressively dimmer and the car eventually started running rough, so I cut it off. The A/C, recirc, high fan, head/tail lights, and radio were on at the time.
The next morning, the car started up, and I checked voltage at the battery.
Stable 13.2v at idle with only the radio on.
Replicating everything from the previous night with the full load - voltage started at 12.5v and slowly went down to 11.6v. I then turned the car off.
Since the battery is relatively new, I thought it was probably the alternator or voltage regulator. The voltage regulator looked worn out, so I sourced the exact part # and replaced it - no change.
I next took the 80a euro market Bosch alternator to Advance Auto for testing (with the new VR). I'm not confident that the employee knew what he was doing, but he supposedly tested the alternator twice and it showed a stator failure both times.
So I installed a Bosch factory rebuilt US spec 90a alternator yesterday. The voltages were a little higher, but the trend was the same.
14.0v at idle cold.
Started at 12.6. with the full load and progressively went down at little slower than before. I let it get down to 11.8v before turning off electrical items.
The tach was non op when I bought the car and I haven't had time to fix it. The idle always seemed low, so I raised it with the adjustment screw. No change.
I next drove it for a while and took more readings.
13.6v at idle warm.
Same as cold with the electrical load.
Steady 12.9v with only the aux fan running.
The block to frame ground wire is intact but crunchy, so I ordered a new one from Bav Restorartions. I also ordered some alligator clip leads so I can check voltage at the alternator when running.
Many of the threads suggested problems with the exciter wire, but that only seems to apply if the system is not charging at all. Also based on other threads, I checked the battery voltage this morning. It was 12.8v, which seems to confirm that the battery is ok.
Any thoughts or advice would be greatly appreciated.
Thanks, Cory
Driving home after dark a few weeks ago, I noticed the interior lights getting dim and A/C fan getting slower at stop lights. When I got home and stopped in the driveway, the interior lights got progressively dimmer and the car eventually started running rough, so I cut it off. The A/C, recirc, high fan, head/tail lights, and radio were on at the time.
The next morning, the car started up, and I checked voltage at the battery.
Stable 13.2v at idle with only the radio on.
Replicating everything from the previous night with the full load - voltage started at 12.5v and slowly went down to 11.6v. I then turned the car off.
Since the battery is relatively new, I thought it was probably the alternator or voltage regulator. The voltage regulator looked worn out, so I sourced the exact part # and replaced it - no change.
I next took the 80a euro market Bosch alternator to Advance Auto for testing (with the new VR). I'm not confident that the employee knew what he was doing, but he supposedly tested the alternator twice and it showed a stator failure both times.
So I installed a Bosch factory rebuilt US spec 90a alternator yesterday. The voltages were a little higher, but the trend was the same.
14.0v at idle cold.
Started at 12.6. with the full load and progressively went down at little slower than before. I let it get down to 11.8v before turning off electrical items.
The tach was non op when I bought the car and I haven't had time to fix it. The idle always seemed low, so I raised it with the adjustment screw. No change.
I next drove it for a while and took more readings.
13.6v at idle warm.
Same as cold with the electrical load.
Steady 12.9v with only the aux fan running.
The block to frame ground wire is intact but crunchy, so I ordered a new one from Bav Restorartions. I also ordered some alligator clip leads so I can check voltage at the alternator when running.
Many of the threads suggested problems with the exciter wire, but that only seems to apply if the system is not charging at all. Also based on other threads, I checked the battery voltage this morning. It was 12.8v, which seems to confirm that the battery is ok.
Any thoughts or advice would be greatly appreciated.
Thanks, Cory