The Best Kind of Charging Issue, The Intermittent Kind - Diesel Place : Chevrolet and GMC Diesel Truck Forums
 
Home Forum Market Place Garage Tuning Library DTC Tool Register Vendors
Go Back   Diesel Place : Chevrolet and GMC Diesel Truck Forums > GM Diesel Engines > 6.2L Diesel Engine
Register FAQ Forum Rules My Replies My Threads Mark Forums Read Advertise

6.2L Diesel Engine Discuss the 6.2 GM diesel engine & associated components.

DieselPlace.com is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
Like Tree20Likes

Reply
 
LinkBack Thread Tools
Old 04-23-2017, 11:36 PM   #1 (permalink)
RatsMC
Diesel Boss
 
RatsMC's Avatar
 
Join Date: Nov 2015
Location: Oakland, CA
Posts: 1,299
iTrader Score: 0 reviews

Old School Oil Burners (Old SOBs) Member

The Best Kind of Charging Issue, The Intermittent Kind

If any of you have read any of my topics, you may have noticed that there is a charging issue that keeps popping up. And then going away

This is a little long-winded but intermittent issues seem to have a long story behind them.

Well, it's back. Today I was driving and noticed my fuel pressure was dropping to 0 when I accelerated on the freeway. Since I installed the P4070 pump, I haven't seen it drop below 3 PSI. At this point, I noticed that my voltmeter was showing just under 13 and not going up when I revved the motor. I stopped and put a real volt meter on it and it showed 12.10. When I started it, it dropped down to 12.08. While it idled, it slowly dropped down to about 12.06 at which point I got on the freeway. On the freeway, it went up to about 12.14 but very slowly and the sat there until I got home.

This didn't happen on Friday when I drove to work and back.

A while back, I made a 70 mile roundtrip to a worksite and didn't notice until I was on the return trip that the battery voltage was dropping. By the time I got home, it was below 12 volts and the alternator wasn't charging.

The alternator was custom wound by a local shop that I have always had good luck with. However, it wasn't charging so I replaced it with a cheap Autozone alternator figuring I'd take the old one back to the shop that wound it.

With the cheap alt in everything was charging fine and everything worked for a while. I took the old alt back to the shop and it tested fine

I didn't put the old (good alt) back n and ran the cheap one for a while. Then suddenly it wasn't charging. This was after less than a month. When I pulled that alt out, the main post was loose so I figured that was my problem.

I also figured that the alternator wiring was causing the issue at this point: two alts just suddenly stop working and when tested seem fine, I assumed that the alternator wasn't getting current. I replaced the wires and installed the old (recently tested) alt. Everything seemed fine until today.

So, I have the same symptom with two alternators (not charging). Replaced the main power wire to the starter, #1 wire to switched power and #2 to the starter and battery positive. After replacing the wiring, I am now getting a weak charge out of a tested alternator.

It is possible that the alt died between Friday and today but it seems unlikely. Could it just be a bad ground? I have new 1/0 ground wires coming because I wanted to do that anyway but Id like to track down this problem before the new wires arrive.

__________________
--
jerry

82 GMC K1500 6.2l

Banks Sidewinder Turbo
TH400 Transmission
Rebuilt 10 Bolt 3.42 Diffs
NP208
Electric Lift Pump relocated to the frame
Manual Glow Plug Set up
Offline  
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 04-24-2017, 12:14 AM   #2 (permalink)
TFLundyB275
Eagle Eyes
 
TFLundyB275's Avatar
 
Join Date: Feb 2005
Posts: 1,329
iTrader Score: 0 reviews

Bad situation you have there because its infrequent so hard to diagnose and its going to leave you stranded someday.

You mentioned grounds so I'll start there. Always a likely suspect, and easy to dismiss. I imagine you have the standard setup that each battery is wired to the engine with same gauge wire. This should be of itself enough ground to not cause issues. Just has to be tight and clean. This includes no paint underneath. I'm sure you know the drill.

Otherwise it simply sounds like your alternators are dead or dying, however, that should not be the case because of how quickly it is happening and how new they are. However, I have run into that case myself when I first bought my truck. Mine was the belt slipping issue, and having the alternator constantly charging depleted batteries with a slipping belt killed it fairly quick apparently.

Usually with weird electrical problems its best to get the obvious out of the way (like the grounds, connectors, etc) then try to isolate the problem. If it was my truck with a mechanical pump I would have everything turned off, the alternator drive belt disconnected, and with the truck running, watch the voltage. Perhaps you can do the same with your pump wired to a spare battery. Can do the same with the alternator wiring disconnected. The of course having the alternator fully connected and the rest of the power harness not.

Because your problem is intermittent its difficult to do those tests.

Its interesting that while you are driving you are suddenly that low on voltage. Normally if you had no power demands and the alternator suddenly quit the battery would just taper down to standby voltage, like 12.5v on a strong battery. I'm guessing you would know it, but a heavy load with a not up to par alternator would do that.

The only thing you didn't mention in your post was batteries, how old they where and quality. They can be either dead, or act weird depending on problem. Have seen them good one minute bad the next, or slowly not want to hold a charge, and even take a solid charge but give it up quickly when a load is supplied. Again with my above example, when my belt slipping was causing alternator issues it quickly because battery health issues as well...

Hope something in my reply sparks an idea. Besides, its a good time to be thankful its not a new truck..good luck figuring out electrical problems then !

__________________
1985 K20 Chevy pickup, 6.2L N/A C code with J code 4544 IP&intake, Fluidampr, 2qt oil filter, dual early spin on fuel filters with inline heater
CS144 140amp alternator with dual belt pulley + military pulley modification + belt tensioner, Autometer Tachometer, headlight relay upgrade
4/0 starter and crossover cables, THM700R4 w/ cooler, NP208, 3.73 s/f, C30/1 ton springs (3 front, 9 rear)
Superwinch locking hubs, front & rear Eaton Positraction, BFG Commercial Traction 235/85/R16E tires,
dual 2.5" glasspack exhaust, Z75 quad front shocks, Class IV 12000 lbs GTWR trailer receiver, headlight relays, CB and Ham Radio.
----------
2019 Chevy 1.6L TurboDiesel Equinox LT AWD
----------
Allis-Chalmers CA, Case 530CK Loader/Backhoe with 188D 3.1L N/A Diesel engine, Eager Beaver 5 ton dual axle trailer, MEP002a Onan Diesel generator

Last edited by TFLundyB275; 04-24-2017 at 12:19 AM.
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 07:32 PM   #3 (permalink)
RatsMC
Diesel Boss
 
RatsMC's Avatar
 
Join Date: Nov 2015
Location: Oakland, CA
Posts: 1,299
iTrader Score: 0 reviews

Old School Oil Burners (Old SOBs) Member

Thanks. Some more info from a few minutes of testing today.

When I put a voltmeter to the batteries, they show 12.32 which is higher than I was getting on the freeway. So, I thought maybe it was just the wiring in the cab and the alternator is fine. I ran a test wire from the main terminal block (direct between the starter and the alt) to inside the cab. Before I started the motor, I got 12.32v. Once I started it showed 12.06 no matter how much I revved the motor.

Next step is to replace the grounds to the batteries. The stock ones seem okay but I don't know what they look like under the insulation.

I could pull the alternator out and have it tested but I want to rule out the grounds first. It seems that every time I pull out the alternator and swap it with another everything is fine at first and then goes wrong. Maybe disconnecting the ground cable for other stuff (like swapping out the switched accessory power solenoid) is fixing/unfixing the issue.


Oh, and the batteries are Diehard Golds that are about 2 years old. If I was still living in Phoenix, I would have started with the batteries but they should be good still.
__________________
--
jerry

82 GMC K1500 6.2l

Banks Sidewinder Turbo
TH400 Transmission
Rebuilt 10 Bolt 3.42 Diffs
NP208
Electric Lift Pump relocated to the frame
Manual Glow Plug Set up

Last edited by RatsMC; 04-24-2017 at 07:35 PM.
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 04-24-2017, 09:09 PM   #4 (permalink)
TFLundyB275
Eagle Eyes
 
TFLundyB275's Avatar
 
Join Date: Feb 2005
Posts: 1,329
iTrader Score: 0 reviews

Quote:
Originally Posted by RatsMC View Post
When I put a voltmeter to the batteries, they show 12.32 which is higher than I was getting on the freeway.
Just to clarify, what is the situation when you did this test? Truck sat a while off, or on, or at idle, higher RPM? 12.32V from just sitting is low voltage if the battery is good with no drains.

If you have a battery charger and some time, I would charge both batteries disconnected to 14.5 and then watch how fast they drop. If they slowly go to 12.5 they are fine, if they shoot down they are not good. Leave them like that overnight. If you see an imbalance of good proportion it will show you if you have one bad bringing down the other.

Quote:
Originally Posted by RatsMC View Post
Before I started the motor, I got 12.32v. Once I started it showed 12.06 no matter how much I revved the motor.
A typical drop I suppose on a non charging system. Either the alternator is not producing power or the batteries are not receiving it, or taking it. May not be a true test as everything is connected, but use your meter to test voltage at the alternator terminal.

Would take a bit of work but a real test would be to see how much amperage the alternator is putting out with the tests. Need an expensive clamp on or wiring in a gauge to your charge wire. It is the alternator's amperage that does the work.

Keep in mind severely depleted or bad batteries will refuse a charge or take forever doing it especially with an alternator.

As far as the ground, when I bought my truck the battery cables where shot and a hodgepodge. One had been spliced together and everything. Wound up blowing a connector right off a battery side terminal. The NAPA replacements have the ground on the PS going to the alternator bracket, but I relocated to the intake stud. The DS battery ground goes to intake stud. Each have a smaller gauge ground to the radiator support. Hope that helps.
__________________
1985 K20 Chevy pickup, 6.2L N/A C code with J code 4544 IP&intake, Fluidampr, 2qt oil filter, dual early spin on fuel filters with inline heater
CS144 140amp alternator with dual belt pulley + military pulley modification + belt tensioner, Autometer Tachometer, headlight relay upgrade
4/0 starter and crossover cables, THM700R4 w/ cooler, NP208, 3.73 s/f, C30/1 ton springs (3 front, 9 rear)
Superwinch locking hubs, front & rear Eaton Positraction, BFG Commercial Traction 235/85/R16E tires,
dual 2.5" glasspack exhaust, Z75 quad front shocks, Class IV 12000 lbs GTWR trailer receiver, headlight relays, CB and Ham Radio.
----------
2019 Chevy 1.6L TurboDiesel Equinox LT AWD
----------
Allis-Chalmers CA, Case 530CK Loader/Backhoe with 188D 3.1L N/A Diesel engine, Eager Beaver 5 ton dual axle trailer, MEP002a Onan Diesel generator
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 09:47 PM   #5 (permalink)
RatsMC
Diesel Boss
 
RatsMC's Avatar
 
Join Date: Nov 2015
Location: Oakland, CA
Posts: 1,299
iTrader Score: 0 reviews

Old School Oil Burners (Old SOBs) Member

Based on that, I think the next steps are (in order of effort):

1. Disconnect the alternator charging wire and test that. This is easy since it goes straight to a terminal on the firewall before going to the battery and the truck will run on the batteries while I test.

2. Pull the batteries, charge them and check for draining below 12.5. I'll also take them to the parts store for testing.

3. Replace the ground wire - this should arrive in a day or so.

4. Pull the alternator and have it tested.

If that doesn't do it, I have some weird wiring problem and it is time to just light the whole truck on fire and leave it down the block.
__________________
--
jerry

82 GMC K1500 6.2l

Banks Sidewinder Turbo
TH400 Transmission
Rebuilt 10 Bolt 3.42 Diffs
NP208
Electric Lift Pump relocated to the frame
Manual Glow Plug Set up

Last edited by RatsMC; 04-24-2017 at 09:47 PM.
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 09:48 PM   #6 (permalink)
TFLundyB275
Eagle Eyes
 
TFLundyB275's Avatar
 
Join Date: Feb 2005
Posts: 1,329
iTrader Score: 0 reviews

Quote:
Originally Posted by RatsMC View Post
The alternator was custom wound by a local shop that I have always had good luck with.
It would be interesting to know the history and specs on it. Why did you have one custom wound? What was its amperage? Was it a 12SI body or different?

The autozone one you had in lately, a 12SI as well? What amps?

What belt are you using? Pulley size is stock?
__________________
1985 K20 Chevy pickup, 6.2L N/A C code with J code 4544 IP&intake, Fluidampr, 2qt oil filter, dual early spin on fuel filters with inline heater
CS144 140amp alternator with dual belt pulley + military pulley modification + belt tensioner, Autometer Tachometer, headlight relay upgrade
4/0 starter and crossover cables, THM700R4 w/ cooler, NP208, 3.73 s/f, C30/1 ton springs (3 front, 9 rear)
Superwinch locking hubs, front & rear Eaton Positraction, BFG Commercial Traction 235/85/R16E tires,
dual 2.5" glasspack exhaust, Z75 quad front shocks, Class IV 12000 lbs GTWR trailer receiver, headlight relays, CB and Ham Radio.
----------
2019 Chevy 1.6L TurboDiesel Equinox LT AWD
----------
Allis-Chalmers CA, Case 530CK Loader/Backhoe with 188D 3.1L N/A Diesel engine, Eager Beaver 5 ton dual axle trailer, MEP002a Onan Diesel generator
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 09:52 PM   #7 (permalink)
TFLundyB275
Eagle Eyes
 
TFLundyB275's Avatar
 
Join Date: Feb 2005
Posts: 1,329
iTrader Score: 0 reviews

Quote:
Originally Posted by RatsMC View Post
1. Disconnect the alternator charging wire and test that. This is easy since it goes straight to a terminal on the firewall before going to the battery and the truck will run on the batteries while I test.
Am I understanding you right that your heavy charge wire does not go to the PS battery? It goes to the firewall terminal instead?

The alternator charge wire is supposed to go from alternator stud to PS battery positive terminal.
__________________
1985 K20 Chevy pickup, 6.2L N/A C code with J code 4544 IP&intake, Fluidampr, 2qt oil filter, dual early spin on fuel filters with inline heater
CS144 140amp alternator with dual belt pulley + military pulley modification + belt tensioner, Autometer Tachometer, headlight relay upgrade
4/0 starter and crossover cables, THM700R4 w/ cooler, NP208, 3.73 s/f, C30/1 ton springs (3 front, 9 rear)
Superwinch locking hubs, front & rear Eaton Positraction, BFG Commercial Traction 235/85/R16E tires,
dual 2.5" glasspack exhaust, Z75 quad front shocks, Class IV 12000 lbs GTWR trailer receiver, headlight relays, CB and Ham Radio.
----------
2019 Chevy 1.6L TurboDiesel Equinox LT AWD
----------
Allis-Chalmers CA, Case 530CK Loader/Backhoe with 188D 3.1L N/A Diesel engine, Eager Beaver 5 ton dual axle trailer, MEP002a Onan Diesel generator
Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 10:05 PM   #8 (permalink)
upsmoker
"ol` smokie"
 
upsmoker's Avatar
 
Join Date: Mar 2014
Location: U.P. of Michigan/Wisconsin border
Posts: 343
iTrader Score: 0 reviews

You have a voltmeter, no charge light, correct. Possible your resistor wire to terminal 1 is going bad. Just make a jumper with a small dash light( preferably 2) wired in line for resistance. Most 80`s gm diesel cars that had charge lights also had what they called "hidden" charge lights tucked behind the dash. I tried my truck with the single hidden light, (because there is no resistance wire) and had to put 2 lamps in line. It`s possible your not exciting your alternator
__________________
Quote:
Originally Posted by Bigboytoys View Post
Weeeellll a 6.2 and 5.7 have 3 things in common, you put oil in the pan, antifreeze in the block and it burns diesel
Quote:
Originally Posted by Bigboytoys View Post
Dang it ... your making the quote wrong, 4 things 5.7's and 6.2's have in common, flex ring failures ....

Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 10:20 PM   #9 (permalink)
upsmoker
"ol` smokie"
 
upsmoker's Avatar
 
Join Date: Mar 2014
Location: U.P. of Michigan/Wisconsin border
Posts: 343
iTrader Score: 0 reviews

I`m not familiar with your trucks wiring, but the "BAT" on the alternator can go anywhere that is capable of carrying the load, ie. main + lug on starter, power distribution block on firewall, + whip from battery cable. I`ve seen them all over the place. Terminal 2 on alternator is a monitor wire and should be upstream away from the alternator to monitor usage/demand. Making jumpers for #1 and #2 are simple enough, #2 could be losing connection and showing no demand, #1 (resistance wire)could be going bad not exciting.
__________________
Quote:
Originally Posted by Bigboytoys View Post
Weeeellll a 6.2 and 5.7 have 3 things in common, you put oil in the pan, antifreeze in the block and it burns diesel
Quote:
Originally Posted by Bigboytoys View Post
Dang it ... your making the quote wrong, 4 things 5.7's and 6.2's have in common, flex ring failures ....

Offline   Reply With Quote Quick reply to this message
Old 04-24-2017, 10:27 PM   #10 (permalink)
RatsMC
Diesel Boss
 
RatsMC's Avatar
 
Join Date: Nov 2015
Location: Oakland, CA
Posts: 1,299
iTrader Score: 0 reviews

Old School Oil Burners (Old SOBs) Member

Quote:
Originally Posted by TFLundyB275 View Post
Am I understanding you right that your heavy charge wire does not go to the PS battery? It goes to the firewall terminal instead?

The alternator charge wire is supposed to go from alternator stud to PS battery positive terminal.
Stock it actually goes to the starter and then the battery. I just replaced it with a 4 gauge wire to a terminal block right behind the passenger side valve cover then the starter (with a fusible link at the starter). From the starter, it has a 1/0 wire to the battery.

__________________
--
jerry

82 GMC K1500 6.2l

Banks Sidewinder Turbo
TH400 Transmission
Rebuilt 10 Bolt 3.42 Diffs
NP208
Electric Lift Pump relocated to the frame
Manual Glow Plug Set up
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Diesel Place : Chevrolet and GMC Diesel Truck Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

PLEASE READ! You must check your email inbox for the confirmation link to complete registration. Please check your spam box if you do not see the email in your inbox.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Insurance
Please select your insurance company (Optional)

Log-in


Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Charging Problem JacksonSC Electrical 1 11-08-2016 12:42 PM
Question: Intermittent charging problem with no indicator light destiny 6.5L Diesel Engine 5 10-15-2016 03:27 PM
LML: Do I have a charging issue here ?? PierreB Duramax Fifth Generation: 2011-2016 (LML) 18 10-05-2016 09:42 AM
Intermittent Fuel issue Blackdog3 6.5L Diesel Engine 28 06-16-2016 09:01 PM


All times are GMT -4. The time now is 10:21 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Shoutbox provided by vBShout v6.2.1 (Lite) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
© AutoGuide