alt 2 issues need assistance/advice

[M1009 NEWBEE 2013]

Hi Everyone- Are there any good alternator 2 gurus out there? I need to run an issue by you..
alt 2 was not charging properly, so i bought a new iso ground unit from realelectric and installed it, install went good, no sparks after hook-up, so iso ground part of it was good. At start up, i get both Gen1 and Gen2 lights, no issue, truck starts and both lights go out, after its started.
Here is where the problem comes in, upon acceleration, gen 2 light does random dance of on and off, while running thru the shifts, while it is on and right before it goes off, it glows with a burst of brighter red, then fades and goes out. When truck is at idle, it does not come on, only while gaining speed and until it gets up to speed, then it goes out. As soon as you apply gas, in any manner, it comes on and seems to come on and off with shifts and when applying foot to gas pedal. While parked, if you press the peddle down quickly, it also comes on, then goes out as the engine settles down. I have proper voltages, both running and not running per the tm and the alt appears to be putting out proper voltage at idle. 14.77 V to rear batt at idle and 29.9V combined batts while at idle. I have taken it out twice today and put alt 1 in its place, without any issue, so it seems to be within the alt itself. any ideas on what to buy for alt parts that may be causing this? I even put the old alt back in and this problem went away. So it really appears to be this new alt that has the issue. i have checked and cleaned exciter plug, belt is tighter than tight and like I said, problem only happens with this particular alt. However, this is a new alt and Id like to fix the problem and allow it to operate properly. Can anyone provide what may be causing this or what else to check? I did read the TM and 15 or so stickies here but cant seem to be able to find it, also checked alt2 relay under dash (24v), on/off voltages (all check out) fusible links (all are good) but dont know much about alternators or what to replace or check.
Edit:Id like to add, while truck is at idle voltage gage is at the green line and stays there, it does not fluctuate while light is on or comes on and off. It stays at green line on meter. Just thought id add that.
Thanks Dave

 

[Keith_J]

Sounds like the pulley is slipping on the rotor shaft. Not belt slipping on pulley, as you mentioned the belt tension. Why? Alternators vary the rotor field current, this varies the strength of the rotor magnetic field. As these alternators have claw pole pieces, the AC waveform is less sinusoidal and more trapezoidal. This makes the torque demands vary over the rotor speed. And if there is slippage, heat will be generated which could increase the friction.

Basically, the idiot light senses the loss of voltage off the diode trio as it is insufficient compared to excitation voltage and then enough current can flow through the lightbulb to illuminate it.

Try turning the pulley fan with your thumb while the belt is tight, it shouldn't turn. If it turns, you can hold the rotor shaft by the nut with an 8mm Allen wrench while you tighten the nut with a box end wrench. Standard right hand threads, 50 foot-pounds is the torque specification per -34 TM.

Be very careful on the Allen Wrench, I used a Lisle brand 3/8" socket wrench Allen wrench bit and hammered it in. The TM says to clamp the rotor in a soft jawed vise to torque but this requires the alternator to be partially torn down. My way allows tightening while alternator is mounted in the vehicle.

The only other thing it could be is the ballast resistor on the voltage regulator could be missing. It is $1.08 from Rock Auto and simple to install. Part number is 830478. You will have to take the alternator apart to install, very simple. Remove alternator from vehicle (I know you are getting tired of this...). Take the pulley nut off, then take the 4 screws holding the case together out. The case comes apart, the stator stays with the tail piece. Pull the rotor out, then using a 3" length of 1/16" wire (or 16 gauge solid wire), push the brushes back into the holder, then slip the wire through the holes to hold the brushes in. The 1/16" wire needs to stick out of the vents on the back side of the tail piece, it is removed when the alt is back together.

Now, to install the resistor (ACDelco 83047, it is installed on the triangular ceramic piece that has the twin connector for exciter leads. Remove the two screws on the right side, place the resistor holes over the two screw holes and reinstall the two screws. Slip the rotor into the tail piece, then slip the drive end housing over the rotor. Carefully align, being careful not to pinch your fingers. Screw the case back together and pull the 1/16" wire out, seating the brushes. Reinstall the fan and pulley, noting the collar goes under the fan, then the fan and finally the pulley. Washer under the nut. 50 foot-pounds.

 

[M1009 NEWBEE 2013]

Kieth J, ill run down and check right now and report back. this has been a long day changing out alts to figure this out.

 

[61sleepercab]

I am no expert but if you have swapped alternators and no problem with switch, you have a bad unit on your hands. New today is a relative term as I have heard of people going through 4,5,or 6 new or rebuilt starters , alternators to get a good one. Your unit seems to have some regulator problem with fluctuation of speed and output with the flickering idiot lights. A dead alternator with a bad field or rotor would usually do nothing. I am assuming no loose/corroded wires which could occur even without a visible break in the wire, however your unit worked with the switch. You could try a new regulator on your alternator.

 

[M1009 NEWBEE 2013]

keith j, I just checked it and it was tight. i put a wrench on it and turned it and it spun the pulley and fan fins at the same time but belt didn't move with it, they spun and the belt remained stationary. does that mean the belt is not tight enough? i used a belt tension gage and it says its tight.

 

[M1009 NEWBEE 2013]

61 sleepercab, I ordered a new regulator, rectifier and diode trio today along with a new rebuild kit for the old alt 2. but the voltage meter is back where it should be Vs the old unit and seems to be charging. Ill get the new regulator put in later this week and report back to you. One thing to note is the new unit has a different pulley Vs the old one. Im wondering if a new belt would be in order. The old belt looked good though.

 

[M1009 NEWBEE 2013]

keith j, Ill get the resistor ordered and have my alternator guy do that when the rebuild kit arrives for the old alt. ill have him install that along with the regulator and anything else he may find wrong. i just ordered a new diode trio, rectifier and regulator, just in case and a new kit for the old alt2. Question, is this ballast resistor part of the rebuild kit I just ordered or is part of my old alternator? i guess I am asking because i would have thought it would have been part of the new 27is alt. Is this often missed?

 

[Keith_J]

Tension gauge? Can you turn the alt fan blade with thumb pressure? Then it is either loose or incorrect pulley. The bottom of the belt should not touch the pulley bottom, that is how the belt wedges into the pulley to get friction to turn.

But yes, new/rebuilt units are known to fail. It would be nice to know how much current the alternator is attempting to put into the system. And over what engine speed. But without a DC loop ammeter, carbon pile tester and tach, you will never know.

I have a 1 milliohm shunt I use off the back of alternators, in series, to measure current output. I simply measure the voltage drop off this resistor shunt and the millivolts equals current in amperes. It is a length of coiled 12 gauge solid wire.

 

[Keith_J]

The 40 ohm ballast resistor isn't part of most overhaul kits. Some rebuilds don't have it. I just did mine, using the old resistors and the old capacitors as they are easy for me to test.

 

[M1009 NEWBEE 2013]

kieth j, no it didn't turn with thumb, i thought i was going to bend the fin I pushed so hard, so no it doesn't move. Yes, I have a belt tension device that measures belt tension. it measures how far/much the belt flexes. it says its tight and to tension. its tight, very little movement when pushed/its tight. the pulley that came on my new alt just looks different than the old one but is aligned properly. its a smaller in dimeter pulley. will that affect things? the belt sits up a little higher than flush with the top of the pulley (up a 1/16" off of the top of the pulley) and the belt does not touch the bottom. i used the old belt as it still looks good but have a new one. But when I swapped back to old alt and put alt 1 in alt 2 position this issue does not happen. its only with this new alt. no worries about pulling the alt out, I can unhook it and have it out in 10 minutes. (getting good at it). does the above change anything you have stated previously? ill order the resistor tomorrow first thing. when all parts get here ill let you know what happens.

 

[M1009 NEWBEE 2013]

keith j, resistors ordered. i ordered 3 of them. one for new alt, one for rebuild alt 2 and one for current alt 1 for future rebuild. hopefully this will work. thanks

 

[Recovry4x4]

This has been a refreshing thread to read. I like how the original poster did his due diligence in reasearch and presented the troubleshooting and results of same in the original post. Surely if there was a one word solution to his issue, it would have been posted. Thanks to everyone in this thread for making it a model thread.

 

[Warthog]

Double check the diameter of the pulley. The stock pulley is 77mm and the most of the new ones are 66mm. Makes a big difference on which belt is needed.

http://www.steelsoldiers.com/showthread.php?47479-Correct-Alternator-Pulley

 

[rlltide12]

OP stated that the voltage at idle is 29.9 Volts!!! Id say you have an overcharging issue. Reference this archived thread.

http://www.steelsoldiers.com/archive/index.php/t-50508.html

Edit: Just for reference, my 08 puts out around 28-28.5 at idle.

Edit Edit: Easy way for you to check to see if this is your issue is to turn on your headlights and see if it quits flickering. If so, this is your problem. The headlights are pulling enough current to keep the light off.

 

[M1009 NEWBEE 2013]

Warthog/RT, I will try to take the pulley off of the old alt 2 and see if that fixes things, it is just a little smaller diameter than the old one. Could that really be affecting the voltage and making the light come on? The belt tightens up just fine, with adjustment room, on the bracket.
I drove it with headlights on and fan on high and it still does it. It is putting out 14.77 to rear batt.

Here is what I had yesterday. (I will re-check everything tonight after it is driven home to see what I have) Truck off- rear batt 13.1 front batt 13.1. combined off 25.89 (note this was after sitting and right after install of bad alt and 2 or 3 swaps of the alts to trouble shoot. Truck running rear batt 15.23 front batt 14.77 combined 29.99 again, right after install and idling for 10 minutes.
drove it to work this morning with headlights on, blower on high and volt meter was at green line.
Running down the road, the alt 2 light comes on and off with peddle pressure, then when letting off gas, the light that was on, gets a brighter burst of red, then fades out. At stop light, at idle, no light. As truck accelerates, the light does a dance of on and off but it does not affect the voltage gage.
I am not alternator savvy but have ordered new diode trio's, new voltage regulator's-DR HD 14.8 Vset, and new rectifier's (all from ASP). I'm hoping a new regulator may fix the issue. Keith J mentioned the resistor not being installed, in the new alt, so I ordered a few of those as well. They were cheap, so it couldn't hurt to have them just in case. I also ordered a new rebuilt kit for the old alt 2, from ASP, so worst case, once I get the old alt 2 rebuilt, ill put it back in and pray it works. I have never re-built an alternator before and am willing to give it a try if someone is willing to walk me thru it. I do have a guy I can take everything to this weekend and he can do them in about 45 minutes each, he said, if I bring him the parts.

 

[rlltide12]

If warthog is right, and you have a smaller pully on the new alternator, it is turning faster than it is supposed to be and could be the culprit. Smaller diameter pully, faster speed. 15.23 and 14.77 volts on a battery is mighty hot, or at least it seems that way to me. Someone please correct me if I am out in left field somewhere.

 

[M1009 NEWBEE 2013]

Id also like to mention the problem with the original alt 2 was that the light would come on very dim at idle and it was only seen at night. when pressure was applied to peddle, it would go out. But it was very, very dim and only noticeable at night/dusk and at idle. It was putting out only 13.8 at idle but would put out 14.7 at rev, so that is why I bought the new one. It never did really affect the truck operation although the gage would only be at the line when truck was driving down the road. At idle it was below the green line but still in the green.

 

[M1009 NEWBEE 2013]

RT, OK, Ill get it off the truck and replace it or get the proper pulley diameter (77mm) and see what happens. Warthog?

 

[rlltide12]

My light is dimly lit at idle as well, but i go by a digital volt meter telling my i have 14v on each battery. Mine also goes away at rpms. That other alt might be tired but it sounded like it was doing a decent job.

 

[M1009 NEWBEE 2013]

RT, what might I change on that one, to wake it back up. When I re-installed it yesterday, the symptoms went away and it operated as it always did. If I cant find the proper 77mm pulley, my thought was to take the one off the old alt, but I am thinking I may just put it back on until I can find proper 77mm pulley.
I want to find the actual cause, so I can close/resolve the thread properly and maybe help someone else, so I want to do one thing at a time until resolved. But it sounds like I better get the alt off the truck asap due to over-charge possibility. Ill see if I can track down a 77mm pulley today so I can keep the old alt on the truck.