jimbo
Well-Known Member
Does anybody know what causes this and what to do to stop it? My engine compartment looks like hell and I have never had this problem before. New battery and new alternator, what gives???
Battery Boilover?
- Thread starter jimbo
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1968FormulaS340
Well-Known Member
You are overcharging.
Probably related to the alternator wiring or you have a dead voltage regulator.
jimbo
Well-Known Member
The VR is in the alternator correct?
1968FormulaS340
Well-Known Member
no. It's normally on the firewall.
jimbo
Well-Known Member
76 Aspen R/T 360 elect ign. Stock setup.
moper
Well-Known Member
Regulator is a rectangular box with two wires to it (blue and green IIRC) bolted to the firewall. However, it's odd to me that it would fail on full charge. They usually fail by dropping power to the field wires, thus dropping the output of the alternator (so no charging). If the alternator had an internal short it would full field, which will cause bioling over. BTW, wash the bay with baking soda and water... That's acidic vapor and it will destroy pretty much everything if it's left alone.
67Dart273
Well-Known Member
Here's what to start tracking this down.
Could be a grounding/ wiring/ voltage drop issue, bad cabling
Could be a bad battery
Could be a bad regulator
There are several issues with these old girls pretty much centered around the ammeter/ bulkhead connector issue, SOME OF WHICH may have been changed on your car
Start by---try a good know battery if possibly and easy to do, I.E. you have another good running vehicle
Otherwise, charge the battery, find someone with a "real" load tester and determine that the battery is A---"up" and B---load tests OK
Next, Get your multimeter and do the following, first with all loads (headlights, heater, etc OFF and again with them ON
With the battery "up" start the car, warm it up, and diddle the throttle (fast idle) to simulate "medium cruise."
Confirm that it is overcharging by stabbing your meter probes directly onto the battery posts, what does it read? If much over 14.5 warm, it's overcharging
Now stab one probe DIRECTLY onto the battery NEG post, the other probe DIRECTLY onto the regulator case mounting. What you are looking for is a VERY low reading, the lower the better, zero is perfect. Anything over about .2V (two TENTHS) is too high. This means that you have a POOR GROUND PATH between the battery POST and the regulator CASE.
So look over your wiring, and add a no10 or larger wire from the regulator mount to the engine block, and recheck the charging voltage, "did it go down" to around 13.5-14.2?
Next, check the "hot" side of the path. One your car some of this may not apply, but you still have a "bulkhead connector". On the older cars, you could have "voltage drop" from the battery--through the bulkhead connector--to the ign switch connector--the switch--the connector again--back OUT the bulkhead connector--and to the regulator ign terminal.
JUST LIKE THE ground path, low voltage here will cause overcharge.
SO just like above, in the grounding test, with the engine running medium cruise, get a probe rigged to the ign terminal of the regulator. If it's accessable, the "run" terminal of your ignition resistor is the same place (used to be blue)
Stab the other probe on the battery hot post. Once more, you do NOT want over 2.v (two tenths)
AFTER you've checked the battery, run these voltage tests, and IF the thing is still overcharging, about the only thing left is an actual defective regulator.
A "new" regulator does not mean "good."
Could be a grounding/ wiring/ voltage drop issue, bad cabling
Could be a bad battery
Could be a bad regulator
There are several issues with these old girls pretty much centered around the ammeter/ bulkhead connector issue, SOME OF WHICH may have been changed on your car
Start by---try a good know battery if possibly and easy to do, I.E. you have another good running vehicle
Otherwise, charge the battery, find someone with a "real" load tester and determine that the battery is A---"up" and B---load tests OK
Next, Get your multimeter and do the following, first with all loads (headlights, heater, etc OFF and again with them ON
With the battery "up" start the car, warm it up, and diddle the throttle (fast idle) to simulate "medium cruise."
Confirm that it is overcharging by stabbing your meter probes directly onto the battery posts, what does it read? If much over 14.5 warm, it's overcharging
Now stab one probe DIRECTLY onto the battery NEG post, the other probe DIRECTLY onto the regulator case mounting. What you are looking for is a VERY low reading, the lower the better, zero is perfect. Anything over about .2V (two TENTHS) is too high. This means that you have a POOR GROUND PATH between the battery POST and the regulator CASE.
So look over your wiring, and add a no10 or larger wire from the regulator mount to the engine block, and recheck the charging voltage, "did it go down" to around 13.5-14.2?
Next, check the "hot" side of the path. One your car some of this may not apply, but you still have a "bulkhead connector". On the older cars, you could have "voltage drop" from the battery--through the bulkhead connector--to the ign switch connector--the switch--the connector again--back OUT the bulkhead connector--and to the regulator ign terminal.
JUST LIKE THE ground path, low voltage here will cause overcharge.
SO just like above, in the grounding test, with the engine running medium cruise, get a probe rigged to the ign terminal of the regulator. If it's accessable, the "run" terminal of your ignition resistor is the same place (used to be blue)
Stab the other probe on the battery hot post. Once more, you do NOT want over 2.v (two tenths)
AFTER you've checked the battery, run these voltage tests, and IF the thing is still overcharging, about the only thing left is an actual defective regulator.
A "new" regulator does not mean "good."
jimbo
Well-Known Member
This is the second new battery with the same problem. I'll change the regulator first and go from there. Thanks.
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