This evening, the "battery" indicator light in our '85 300D came on brightly, while the two indicator lights to its right glowed at half brightness. I measured the voltage at the battery, with the engine running, as 12.3vdc, not at all good. With the engine shut down for a few minutes, the voltage rose to 12.6, which suggests the problem I' m having began very recently.

Alternator/regulator? Other thoughts?

Thanks,

Phil

'85 300D, of which I write here
'84 Euro 300D, trouble free today

Phil..I gota a regulator if you want to try it.

Steve

Look on the back of the alternator and you will see a kinda round device about the diameter of a quarter with two screws holding it's mounting plate on. You need to replace that part. It is the brushes. I think they run around $11 or so. When you pull it off you should be able to read the p/n off of the back. Call that number into a local Bosch distributor and they can get a replacement for you. Easy diy'er type of job.

__________________
Jim

My thanks to engatwork for his correct diagnosis.

Since originally posting my inquiry, I had determined that the alternator would charge adequately at sufficiently high rpms, and also that it would charge better when cold than when warm.

This morning, I removed the brushes/regulator, very easily done, and replaced it with an aftermarket set which I had bought locally. Unfortunately, aftermarket was too far after, which took my marginal charging system to no system at all. So, I cleaned the contacts on the old, well worn, set and reinstalled it. For now, the alternator is charging perfectly.

However, now that I've seen the condition of the brushes and how easily they are replaced, I know I'll need to replace the set soon. I find on the Net two choices, oem Bosch at $43.90 and aftermarket KAE at $14.95. Both look identical to the Bosch I removed, unlike the TransPro set which didn't work.

What is your collective recommendation: should I go for the Bosch or the KAE? What makes Bosch so frightfully expensive?


Best,

Phil
'85 300D
'84 Euro 300D

I thought I had kept the box they came in but could not find it. I would go with the aftermarket (that is what I did). They were supplied by the Bosch injection pump rebuild shop I do business with. Only paid around $11 for them.

__________________
Jim

Phil

I got a set from Collin (in back of PT lumber) for a couple of bucks

Steve

Colin is a man I know well, a master rebuilder of alternators and starters. However, 'twas he who sold me the brush/regulator set that didn't work. Perhaps not every '85 300D has the same alternator? Perhaps the alternator in mine is not the original? Perhaps there are electrical gremlins on the loose here in Jefferson County?



Phil
'84 Euro 300D
'85 300D