e30 325 alternator ground...

I believe that it is via the engine block on all but the 4 cylinder models. I have read that the 4 cylinder engines utilize an additional ground wire from the alternator but for your 325ix it should be just utilizing the engine block ground.

Good luck with it, Bob

Thanks! Now, where's the block ground? Seems like I'd see other symptoms if the block wasn't grounded (like it not starting, since I assume the starter is also grounded there) ....

I'm assuming it's the ground since a meter: on the + terminal of the alt. and the alt. chassis I have 14.1v on the + terminal of the alt. and the pass. side grounding point I get like 11.5 on the + junction block and the alt. chassis I get 14.1 on the battery itself I'm also seeing 11.5...

Best way to check for a decent alternator ground is to get a really good clean connection to the body with a DVM and the same to the chassis, then measure the voltage drop (engine running at a fast idle) with everything turned on - headlights, heated windows etc. It should be less than 0.5 volts.

Thanks -- I'll give that a try..

-Aaron

Doesn't the alternator ground through the case? You know, the metal case that is attached by bolts to the metal braces that are attached by bolts to the metal engine block, that is attached to ground by the metal cable that is connected to the negative post on the battery.

Where do the knee bone and the thigh bone fit into all this?

Any alternator is grounded via it's casing which is bolted to the engine that is mounted on rubber fixings. A rather fat cable is usually routed via the belhousing or some other place on the block (or even the g/box) to the vehicle shell or if the battery is in the boot/trunk - straight there with the positive lead next to it. However it might be worth remembering that electricity travels from NEGATIVE to POSITIVE so check both connection for damage or crap fittings as the underside of a car is a very hostile environment.

Charging problems usually manifest first with a diode breaking down and allowing battery current to leak to ground. Rapidly followed by the regulator pack.

Sir Hugh of Bognor

The difference between men and boys is the price of their toys. Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK

They help kick the car when all this isn't working properly I suppose.

How's the engine grounded to the chassis of the car? Is there a seperate grounding cable (if so, where's it attach?) or is it just done via the mounts?

-Aaron

Ah ha- this is what I was looking for -- do you (or anyone) know where on the engine in an e30 the cable attaches? The battery is in the trunk, but the negative battery terminal is bolted directly to the chassis.

The mounts are some form of rubber so not much use. There's always a flexible ground cable somewhere - it shares duty between starter and alternator, usually. If this is missing or broken the heavy current when starting can sometimes find another path - via a throttle cable etc and cause problems, like melting it. ;-)