electrical/starting issue, insight needed

[MosportGreen66]

Hey Guys,

If the mods want to delete this because its not musclecar-specific, no problem... You guys know mechanics better than I do. I'm just seeking out help.

My BMW is having an electric/starting issue. Its an '85 528e with 62,000 miles in really nice original, unabused shape. The problem started Wednesday. It started fine but needed a jump start after being driven roughly 3 miles and parked for 20 minutes. Later in the afternoon, it needed another jump after being driven a mile and parked for 5 minutes. On Friday, after sitting for 2 days it started up fine. Tonight I took the car out in the rain and it started up fine after sitting all night no issue. Then after driving for about 15-20 minutes max, I parked the car, finish my errand come back to drive home and she won't start. I had to have the car jumped again.

First I thought the issue was the battery but after charging the unit, I know its the root of the problem. It is also an 8 month old Optima Battery. Maybe the battery is contributing, but I have a feeling it’s not the sole problem.

I took the car to Pep Boy's (Auto chain store) and had them test the alternator. The test came back fine and there were no abnormalities found.

Now I am thinking that the issue is the voltage regulator. This whole issue has never happened before...

Any insight would be most appreciated... what mechanical issue do you think it causing the problem?

Thanks.
-Dan

[SuperNovaSS]

I have had problems on late model Toyota pickups not hot starting. The issue has always been the wiring going to the solinoid. It degrades and develops high resistance when hot.


Jason

[MosportGreen66]

[ QUOTE ]
I have had problems on late model Toyota pickups not hot starting. The issue has always been the wiring going to the solinoid. It degrades and develops high resistance when hot.


Jason

[/ QUOTE ]

Jason, what wires in particular do you think need replacing... do they have a name.

Thanks.
-Dan

[StriperSS]

I would check any of your main positive and negative cables. Make sure they're tight first of all. Then as mentioned they could be degraded somewhat.

John

[Lynn]

Dan:

Between my brother and I, we have owned over 40 bimmers. Currently have 7 in the family. Check to see that your alt belt is not glazed or just a bit loose. On an 85 model, there are rubber bushings in the alt mounting holes. They get real spongy over time and the alt gets just a bit cocked, making it more likely to slip the belt just a bit. With the engine off, if you can "spin" the alt pulley with your hand using just the leverage you can muster with the alt fan, then the belt is probably slipping and not charging the battery sufficiently. Tightening the belt will only be a temp fix. You will need to get new mounting hole bushings. Easy to replace.

If the alt tested fine then the regulator is probably OK. It is integral, with the brushes built in, and, believe it or not, can be replaced easily without even removing the alternator. Take out the two mounting screws and the assembly comes out with the brushes attached. New one comes with new brushes. However, NORMALLY, if the brushes are worn out the red light on the dash starts coming on intermittently. The regulator itself is electronic and RARELY goes bad. I have never seen a bad one.

Hope this helps.

Lynn

[Kurt S]

What the voltage at the battery when:
- it's operating normally (but key off)
- engine running
- when no start condition occurs