intermittent charging after internally regulated alt.

[gearhead]

I installed an 60 amp alternator from a subaru onto my 74 620.Where the external regulator was I spliced the wires together like I was supposed to.I even used solder.The setup worked great for a little bit then  It seems like I am getting an intermittent field and the battery doesn't charge.I can touch the WR/WB and the Y/W together once and it will charge for as long as the car is running.Today I am going to clean the corrosion off the fuse panel and see if that's the problem.Anyone have any other ideas?The stock alt worked great at charging the battery as long as full load wasn't at idle.

[DanielC]

I am not sure about 620 trucks, but 521 trucks had a ground wire from the alternator frame to one of the bolts that held the voltage regulator to the inner fender.  There is also a ground wire from the alternator frame to the negative battery cable, where it attached to the head, just back of the fuel pump.

 

Just because your alternator is bolted to the engine does not mean the alternator frame is grounded.

[datzenmike]

Current flow is the same in any part of a circuit. If you have a 60 amp alt output it also has 60 amps to the ground. Yes the case is bolted to the block and there is the adjusting strap to the timing cover but it never hurts to have a dedicated ground wire from the case to the block. Ideal is to the bolt behind the fuel pump where the ground cable from the battery is bolted... can't beat that. And don't cheap out on it get at least 12 gauge wire. Crimp on good solid lugs.

 

My 100 amp swap had two 12 gauge ground wires. I crimped a lug on and bolted it to the motor mount bracket. 

 

I'm not a big fan of those small blue/ red/ yellow blister pack crimp on 'lugs'. Okay hidden under the dash but look cheap. I went to a fastener store and for $2 got the real thing.... Solder and heat shrink.... why not??

 

The black one with the blue stripe is a 4 gauge power wire from the alt. The other wire is the positive battery cable... yup, it's smaller.

[gearhead]

I have a dedicated 4 gauge cable from the block to the frame.So I need a better ground from the alternator to the block?I connected the stock ground wire to the alternator when I installed it.

[datzenmike]

The frame is isolated from the block by rubber motor and trans mounts, rubber bushings on leaf springs and the shocks. Won't hurt to ground to the block as the ground cable from the battery is bolted to the head.

[DanielC]

Pickup can be a major PITA to have all the necessary grounds.  You have a bed, a cab, a frame and an engine.  All four parts are mounted in rubber, for vibration reasons, but all four parts have to have a good ground connection.

You also need a good connection from the battery to the engine, both terminals, positive and negative.

The most current flows between the battery, and the starter.  Those two cables need to be the biggest.

[gearhead]

Ok, right now I have:

4 gauge wire from BAT + to starter solinoid

4 gauge wire from BAT - to block

main ground junction from BAT - to right fender

10 gauge wire from alternator case to right fender

6 gauge wire from alternator output to BAT +

4 gauge wire from starter bolt to frame

 

so I guess that just leaves me needing a ground from frame to body,and box to frame.

 

However,I am still having problems with an intermittent charge.I know the field wire is hot whenever the ignition is on,and that it goes from the fuse box to the alternator.I want to check that wire out so what color is it at the fuse box on a 74 620?Does it go through a bunch of connectors on its way to the alternator?I would like to keep the idiot light,but if I have to I will find a 12V switched power source and run a wire directly to the alternator.

 

 

BTW the charge light in the dash will turn on when the key is turned to ignition,then go out once it starts.It wont however turn on when the alternator isnt putting out juice.The only indicator of low voltage is when I have the headlights on at night and they dont light up the road.

[banzai510(hainz)]

why dont you put A VOLT METER ON THERE and monitor this at different load levels.

No accessories on

then put on lights , heater and monitor the voltage then you can tell if you just got a weak alternator or one that is rwady to go out.

I have a VDO volt meter on my 510 but on my truck i just use a one of those Cig light type diaode volt meter and thay work great.. You caANT ELL WHATS GOING ON AT IDLE OR HIGHER rpm. and differnt load levels

 

theres different versions of this. I had one and worked great but they are only worth about 10$ but it broke. it can tell if your overcharging also .

http://www.equus.com/Product/3721/Battery-Monitor

[gearhead]

Ive been using a multimeter to find out voltages.So far when everything is right it will show 14.4V at idle across the battery terminals with the truck idling but there is no consistency to that reading.drive the truck or rev it up and it might change to 13.2V or even 11.59V. Not to mention you can actually hear when the field engages and the alternator is working.

 

Ive thrown everything I know into getting this truck to charge. Ive had the alternator off multiple times and each time it bench tested flawlessly.I even had the charging system tested in the truck and at that particular moment it was charging at 13.5V and 38 amps at idle with the high beams on.Yet on the return trip back to my house it didn't charge and it wouldn't start again when I shut it off in front of my house.

 

so right now I need to examine the field and sense wires to the alternator.Yea it probably could use a voltage gauge(and also a water temp and oil pressure gauge),but I dont want to put any more money into it until I get it so I have a 75% chance of getting to my destination and returning home.Right now its about 25% because the truck stalls out when I press the brakes and if its not charging Im dead in the water in the middle of an intersection(It stalls out less now that I added all those grounds,but it still will stall sometimes.)

[banzai510(hainz)]

so right now I need to examine the field and sense wires to the alternator???

 

if this is true then your volt meter would show this.

This happen to my 521. I use the standard external volt regulator. but I would start the truck the volt would get killed. I swapped 2 different alternators and volt regs. I would pop a fuse. but truck would still run.But not charge.

 

If I remember right I would loose the 12volt exciting the alternator. All I did was pull the instrument clister and reseat the plug in back. Some how it went to the dash and returned back to the alternator.Must have been a high resisitance short.

 

 

make sure your Shorting the correct colors and go by the color on engine side of the harness.

I seen after market volt regs that people use to make the short plug using the connector. the colors are correct but they on the WRONG pings