Alternator producing lots of battery acid. Replaced battery. Nada. When I purchased one new they tested the old and said okay. Hummm. Replaced voltage regulator. Nada. Puts out 12.3 volts on the battery terminals. Old one looked fine. No problem. Took it to Advance and they spun the alt on a machine. Putting out 14 volts. Removed neg battery cable from fender, cleaned and sanded connection. Belts okay. Now I have a touch less than twelve. There is a history of damage in the area due to the original battery acid problem. Oh, I did check the ground on the trans. Any input appreciated. Dave

12.3 at battery terminals indicates a problem in the alternator or regulator. If the alternator is putting out 14, then it sounds like a bad regulator. It should be reading in the high 13's or 14's at 1500rpms or so.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Thanks Kerry, but I did replace the regulator. I've been cleaning things, sprayed out the plug on the back of the alternator. Cleaned the neg cable attachment on the fender and the main gound. Doesn't makes any sense. I can't find anywhere down the line to check the output other than the battery. That's below 12 volts at an idle. Goosing the accelerator does not cause the headlights to get stronger either.

dumping acid indicates overcharge.
you could have an AC voltage issue. take the car to a REAL auto electric shop and have them test it. likely you need new alternator though.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Funny you mention that, Vstech. When I started out that's what I was expecting to find. So far, bench testing shows 14 volts out of the car and it had a new voltage regulator on it. Once reinstalled it's doing less than 12 volts. How can you square that info. Seems to be conflicting. Thanks

Maybe something is shorted and drawing the current down to 12 Volts.

The Alternator is charging and maxing out the amps and that is causing the acid to boil; but is unable to go above 12 Volts because of the short circuit drawing it off. (In this by short circuit I am meaning something is on that should not be on.)

__________________
84 300D, 82 Volvo 244Gl Diesel

Is your battery light on? are you checking voltage at idle or about 1500 rpm? If the plug firmly seated in the alt? are pins bent in the connector? Another thing to consider is bench testing for voltage is ok but it must be load tested to know if the alt is giving up on life or not ( a good reg will set voltage at 14 but alt might be in poor condition and only able to muster 12)

__________________
1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

It sounds like you have a connectivity problem. When you did your voltage checks where did you connect the black lead of the volt meter? If it was on the case of the alt & you have low voltage @ the battery , you may have a bad connection some place between the alt & the battery + terminal. Go clean & tighten every joint. If you have 13 0r 14 volts when you do this & only 12 when you have the black probe on the - of the battery then you have an earth connection problem. You need to be doing the test with the lights on & the motor at fast idle.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Charge the Battery and take it to be Load Tested. This is to see if the Battery itself is the issue.
Or if you can barrow a known to be good Battery from another vehicle that will start your Engine; use that in your Car and see what your Voltage is after it is running.

It would not hurt to clean the connections of the Ground Starp between the Engine and the Chassie.

__________________
84 300D, 82 Volvo 244Gl Diesel

info is missing.

if the car running is only producing 12v what is the voltage with the key on, but engine not running? try this. start the car, measure the voltage at the battery. leave the key in the run position, and hit the stop lever on the motor. measure voltage again. what is it?
your meter is measuring DC voltage. your alternator could be putting out 30 or so AC voltage too... that would certainly boil a battery.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

If the battery is TOTALLY full of water then it will "dump acid"- even when the alt is charging normal. Maybe this?