Flakey idiot lights/charging problem. HELP!

[charliechitlins]

'91 300 D
This happened after some VERY cold weather here.
I would be driving and the SRS and ABS lights would come on.
Headlights would dim, wiper moved slowly, radio went off.
Then the dash lights would go off, and everything would be "normal".
Later in the day (after sitting for 8 or 9 hours at work) the car would turn very slowly when starting.
For a few days, I charged the battery at work and home.
I thought maybe a bad battery was causing this (not enough juice to properly operate the relays?), so I replaced it.
The car was fine for a few days but it did it again on my way to work today.
Alternator is only about 3 yrs old.

[stormtigers]

Check Voltage Regulator first by the sounds of things.
And think about putting a new OVP Relay ~!

Check battery is putting oout the required voltage !

[charliechitlins]

Thanks...
A couple questions and an answer.
The guy at the parts store checked the battery right there when I bought it and it's good.
What's an OVP relay? One of the ones behind the fuse panel? I suspected something might not be right with one of them.
How does one check the regulator?
Thnak You!!

[Real1shepherd]

With the car idling, put a VOM across the battery terminals; should be 13.4 volts or higher. Higher than 14.2 with no accessories on indicates overcharging. Voltage reg unscrews from the alt...two screws. Can be a bit twitching fishing the new one in with new/long brushes. As usual with these cars, don't FORCE anything.

OVP(over voltage protection relay) is near the battery, behind that flimsy plastic shroud. It should have two fuses in the top-that would indicate that someone replaced it at some point(doesn't mean it's 100% though-just improved design over the one fuse unit).

Buy OE for these two devices, as saving a buck will probably buy you more trouble down the road. If it hasn't been done already, through away all the aluminum fuses and buy copper. First thing you learn in HS chemistry is that copper and aluminum react together from electrolysis-the air carries the charge in this case. I'd like to think this and the biodegradable soy wiring harness was some kind of 'inside' German engineering joke.....but doesn't seem to have been.

Kevin

[charliechitlins]

Cool.
Thanks.
I guess I'm getting old, but...regulator inside the alternator?
Shouldn't it be a black box bolted to the firewall that says "Auto-Lite" or "Delco-Remy"?
Next thing, you'll be telling me that they're putting fuel pumps inside the gas tank and clutch slave cylinders inside the bell housing!

[sbaert]

Originally Posted by charliechitlins

Cool.
Thanks.
I guess I'm getting old, but...regulator inside the alternator?
Shouldn't it be a black box bolted to the firewall that says "Auto-Lite" or "Delco-Remy"?
Next thing, you'll be telling me that they're putting fuel pumps inside the gas tank and clutch slave cylinders inside the bell housing!

There are no AutoLite or Delco-Remy parts inside any W124!!! That junk is reserved for GM and other Detroit iron.

[charliechitlins]

Just had a fun drive home with no lights.
Couldn't even roll down the window to use hand signals!
I'm thinking a brand new battery would charge itself up enough over 8 hours to start the car.
Does this implicate the regulator?
Could the OVP be involved in this condition.
Thanks, y'all.
I'm a half-assed mechanic and I'm poor as hell so I have to try to do as much as possible myself.

[sbaert]

+1 on voltage regulator and measuring voltage output. Anything below 13V or above 14V is no good.

Being a diesel, make sure you use a group49 size battery. Do not accept anything else.

You need that big battery to crank a diesel that has over 20:1 compression, especially during low temps.

You can get a Bosch group49 batt for about $100 @ Pep Boys.

[Real1shepherd]

Originally Posted by charliechitlins

Just had a fun drive home with no lights.
Couldn't even roll down the window to use hand signals!
I'm thinking a brand new battery would charge itself up enough over 8 hours to start the car.
Does this implicate the regulator?
Could the OVP be involved in this condition.
Thanks, y'all.
I'm a half-assed mechanic and I'm poor as hell so I have to try to do as much as possible myself.

DO the voltage check as directed. Could be something draining your battery as well...but check the output @the battery first.

Kevin

[charliechitlins]

Originally Posted by Real1shepherd

DO the voltage check as directed. Could be something draining your battery as well...but check the output @the battery first.

Kevin

Gotcha!
Thanks.
Is it possible that I could be driving around with basically no electrics working and still be showing a charge coming into the battery?