Eating Voltage Regs

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Eating Voltage Regs

Postby Douglas » Tue Sep 05, 2017 5:31 pm

My 1990 is eating voltage regs. I scoped the battery looking for a shorted diode in the 3-phase bridge, but saw nothing useful( liddle ripples, all the same size ). I tried measuring the voltage reg case to batt negative voltage and got a steady 39 mV( black lead to batt, red lead to reg's case ).

Am tempted to start throwing parts at it, but I'd rather just fix what's broken, yes?
1990 D250, NV5600, 16cm housing and PAC brake, Powr-Lok'd 3.07's, HX35...IC next

1991 D250, 727 and 16cm H1C.
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Re: Eating Voltage Regs

Postby laneends » Mon Sep 18, 2017 8:15 am

I got tired of that game pretty fast, I ran a new relay controlled by the old field exciting wire, and had an internal regulator installed in my alternator. problem free for two years now.
1990 D-250 with getrag 360: pyro, boost, volt, oil pressure, fuel pressure, and water temp gauges, hot screw, 366 gov spring, THD pin, M&H dynamic timing spacer, throttle linkage adjusted for full travel, 4" turbo back exhaust, THD's LPPLP, BHAF, south bend clutch. THD 5x13 comps, 362sxe, 3" crossover, pump to the head
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Re: Eating Voltage Regs

Postby BobS » Mon Sep 25, 2017 5:31 am

Run a wire lead from one of the mounting screws of the voltage regulator to the engine or the alternator. Also run another lead from the negative battery post to the rad support. You live in Michigan. Your truck has been subjected to many years and miles of corrosion to the point where your grounding to the cab and the regulator may have become intermittent.

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91.5 W250 NV4500 Conversion
89 D350 Stock
92 W250 Crew Cab finally in progress
86 D150 wannabe 4BT
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Re: Eating Voltage Regs

Postby bkramer13 » Fri Aug 31, 2018 12:23 pm

Hello. I had a multi year issue of blowing voltage regulators. Narrowed it down to water intrusion. I started cutting the voltage regulators apart, and found that the wires within the regulator were not fully embedded in resin. They are embedded in sand and capped with resin. The stock location of the regulator facilitates the water intrusion. My fix (which has been great for 2 years now) entails moving the regulator under the passenger hood hinge. Applying silicone to the perimeter of the resin on the back side of the regulator, and silicone around the base electrical fitting. I live in a very very rainy place, this issue first showed its face when i moved here, and after finding the water in every one of my regulators led me to this fix.
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Re: Eating Voltage Regs

Postby cougar » Sat Sep 01, 2018 8:44 am

The fix:
Replace your ignition switch. All the power goes through it and they do wear out.
Use the wire coming from the ignition switch to power a relay instead of directly to the regulator. Power the regulator through the contacts of the relay directly from the battery.
Ground the regulator case.
Clean every ground you can get at and use copper anti-seize between the contact points. This keeps corrosion out for a very long time.
RIP 91.5 W250 5 speed. The great experiment.
92 W250 HD 47RH with Compushift. Upgraded H1C to 60/60/16, Scheid Lightning VE, 60# valve springs, DAP 7X.010 injectors, 4" DE exhaust.
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