Weird charging issues. Seems to affect Idle?

[MantisX620]

Hi again Ratsun,

 

Started my truck today and I can see the charge light blinking sporadically. I can hit the gas and it will go out for a while and then start blinking again.

 

So I tried the alternator test of jumping a wire from alternator BAT terminal to the F terminal and my voltmeter read no higher than 12.60 volts off the battery terminals with the truck running. I could hear something on the passenger side wall kick on when I connected the 2 terminals.

 

I also have a volt gauge inside the truck and when the charge light is off, its charging at around 14.7-15.4 or so volts. when it comes on, it drops to 12 or so. When the voltage is low, the truck tends to want to idle higher on its own.

 

I figure ive narrowed it down to the alternator or the regulator, but the regulator is fairly new at just under a year old. One other thing I should mention is I seem to have a new slight whirring sound in the engine bay that wasnt there before. I cant pinpoint it to the alternator but maybe?

 

Thanks all

MantisX

[datzenmike]

Tighten the regulator down so it is well grounded. Unplug and plug in several times to clean the contacts in the connector.

Clean and tighten the battery cables and the other ends where they bolt to the head (negative) and the starter post.

Find and clean/check that there is a good ground strap from the negative terminal to the body sheet metal. Make one even. Run a heavy gauge wire from the block or head to the firewall.

Be sure the wires to the alternator are clean and making good contact. Make sure the alternator is firmly bolted to the block and that the belt is tight and not slipping..

[DanielC]

Here is another possibility. The alternator brushes are worn. When they make good contact inside the alternator, it works, and voltage goes up to 14.whatever.

It takes some power to make electricity, and this drags the engine RPM down. This is normal.

When the charge light comes on the alternator is not charging. The charge light is suppose to come on then.

[MantisX620]

That is an interesting take and sounds the most likely.

 

However, ive decided to bite the bullet and do the saturn alt swap. I went to a pull apart today and scored a very clean looking reman from a 94 saturn. I have the get the turnbuckle, pulley and pigtail and im off!!

 

Ill let you guys know if this solves my issue. I figure this is doing away with the regulator and a possibly bad alt so I should see a difference.

 

Thanks

MantisX

[MantisX620]

Well I completed the saturn alt swap today and all my issues are gone! Lights are brighter and the damn thing even idles better. I think im going to still need to grind the idler arm bolt though because sometimes when I take a sharp right turn, I can feel more engine vibration than normal.I figure the engine is flexing the alternator onto the bolt and sending the vibration through the cab.

 

MantisX

[datzenmike]

Shorter belt? This will pull the alternator over and hug the block.

[banzai510(hainz)]

sometimes just getitng s new belt we be ok

 

old one might be stretched.

 

77620 so I assume a L20 belt.

Some times you could try a l16 belt from a 72 datsun 510(tell the part store guy)

[datzenmike]

I used a 720 alt on my 620 and would hit the grease fitting on the idler arm. Used a shorter belt but the only way to get it on was to install the belt onto pulley then bolt the alt to the block. I think I used a 720 mount to the block as this lifts the alt slightly. A 280z or zx lower rad hose inlet is also handy to move the lower rad hose more to the rear for added clearance. The z/zx inlet is angled back more than the L 4 which sticks almost straight out.

[DanielC]

This belt on a L-16

Another belt on an L-16

This is with some random IR alternator. I think it was on a JDM L-18 engine I bought many years ago. But there is enough time to pretty much guarantee my memory is faulty.

[MantisX620]

Loosened my turnbuckle tension a tad and that seemed to fix the issue. Im going to either try a shorter belt or maybe grind a tad on the alt case. Its not much space there thats making it touch.

 

Thanks all

MantisX

[banzai510(hainz)]

I grinded the idler arm big NUT

[flipsteresis]

I just installed the AC Delco 12SI alternator - ( similiar to the saturn ) the constant voltage and strong spark make the whole car ride more powerful.... I am very pleased - so long as I don't burn my wire harness with all this new power -

 

SOOOOOO

 

Relays on headlights, High and low, and another for the parking/running lights - especiallly since I will be towing a trailer - seperate lines from battery release load on the wire harness...

 

had to make a special bracket to mount it - it was worth it though... Charging system was always a pain in the A$$ and wallet with this caranyways... Thank you RATSUN folks for the tip!!!