Hey guys, 

After a long saga of chasing my tail, I figured out that my alternator was shot. I had previously measured it with cheapy multimeter and it was holding a .02vac so I sort of put it at the back of my mind and kept on going. Anyway, I realized that my power probe had a true rms setting and remeasured and saw some pretty bad numbers.

 

I picked up a 02 Durango 160 amp hairpin alternator from O'Reilly today. I had them test it before I took it and it tested at .36. They couldn't get another until next Tues so I took it.  I installed it, and at idle its pretty much what it tested on the bench at the store. When the grids cycle on, Im seeing about 1.65vac. I couldn't find a reference for what is acceptable. It settles back around .03vac once the grids turn off.

Id love some input to whether that's normal and acceptable.

Here's a quick vid you can see the spike near the beginning when the grids turn on.

John

Edited November 14, 20204 yr by JHFIII

Switch out to rain for me but high country above is going to buried quickly. 

 

New Meadows, ID at Smokey Boulder

 

McCall ID top of the Goose creek grade.

 

Wow cool! Thanks Mike. It's warmed up a bit here as well. Supposed to get hit with another good one tomorrow.

Things to think about... 

• W-T ground wire mod really does cut back the amount of AC noise fed back to the ECM and PCM which the PCM will carry that AC noise right to the field and cause it to amplify the noise.
• Good block and body ground are REQUIRED. If you measure above 0.2 voltage drop  from battery negative post to block replace the cable(s). There is zero need to a negative cable jumper you can test by hooking up jumper cables between both negative post and measure the voltage drop with or without the jumper if there is any change change the block and body grounds. If there is no change like my truck where the voltage drop remains 3mV DC with or without a negative jump this means that it does NOTHING and has zero benefit. Actually the block can flow way more current that a jumper cable. Hence why it does nothing. 
• Make sure your alternator is bench tested for AC ripple. Typically a full load test will create a value around 1.0 to 1.2 Volts under full load on a test stand. If the alternator is passing on the test bench it will pass on the truck as well. 
• Grid heaters draw way more than what the alternator can charge at an idle. Don't start your truck and leave idle to warm up at 800 RPM. This is where I typically use either Mopar1973Man high idle or the Quadzilla high idle to up the RPMs to 1,200 this increase the charge rate more, increase air movement around the diodes keeping them cooler. Reduced the stress on the alternator.
• Bad battery cables are far more common than you think. Voltage drop test is a excellent way to verify cables and terminals for good function. Being you testing under the high loads. 
• "Black" terminal is a lead that is oxidizing, typically a positive post. Engine oil helps reduce the amount of air contact and the acid contact on the terminals. Terminals need to have that fresh lead appearance. Lead oxide is will resist current flow, typically creates warmth to heat at that spot too. Running you hand over terminals careful and wire if you feel heat that cable is failing. 
• Bad rotor brushes in the alternator can create AC noise as well. Some local shops could do the replacement in just like 15 minutes and retest for AC noise. (DuroBuilt, Nampa ID) - Thank @AH64ID 
• Consider reducing total loads on the electrical system. Like I've done HID headlights which are only 35w for both. Driving lights are 18 for both. Previous light was four 100w flood lights and halogen bulbs (45w /65w). LED's are fraction of the electrical load. Look at other stuff like blower motor too if you fan only work on high the bearing are gone and the blower resistor over heated and blew out. Replace both and you'll reduce you electrical loads there. Disconnect the grid heater if you in warm climate and don't require them. 

2 hours ago, Mopar1973Man said:

Bad rotor brushes in the alternator can create AC noise as well. Some local shops could do the replacement in just like 15 minutes and retest for AC noise.

 

You can replace them yourself,  It's a very easy job,

 

 

 

Wow, 

Thank you guys. Never ceases to amaze me the amount of experience and effort people on this forum put out. I tested my new alternator full warmed up with no acc on and she holds solid at .03. That seems acceptable.

 

Just to add some detail, I was having a bad misfire when I got up to about 45mph. Previously I had changed out a bad vp44 for a DAP unit, and I also had a totally blown up ecu just prior to that, most likely from either a bad ground or the bad alternator I just switched out. In any case, I had been chasing my tail because I had no codes whatsoever and was beginning to doubt the new ecu, or think the apps was going. It almost felt like the vp44 was turning off and on. 

Up to this point I had

-Done the WT mod

-Changed the apps over to a timbo 

-Verified wiring integrity ad nauseum 

-Changed alternator

(The apps and the alt needed to be changed regardless, so I didn't waste any money)

And my whole charging cable system is pretty bomb proof, all marine 2/0 tinned lugs, mil terminals etc.

 

Welp, yesterday I found the culprit. See pic below. The #2 injector tube got buggarred somehow. Some junk mustve got into the line nut the when I changed the vp. Dont know how, I'm pretty good about cleaning things that touch sensitive things. It was hiding behind the air horn and weeping just enough fuel to not be noticeable. Luckily I had a spare set of injector tunes and sanded the flare very lightly with some 1300 grit. Sealed right up and runs like a raped ape now.

The irony of the whole affair is if someone had the same symptoms and asked for my advice the first thing out of my mouth would've been, "you're getting air in your lines somehow"

So, thats my Slingblade moment. "It aint got no gas in it"

Btw, Mike, I did consider Durability in Nampa. There is usually a pretty decent fish and chips food truck parked there, too! I just wanted to try thr off the shelf option of the 160a Durango hairpin. Seems to be working pretty well so far!

Edited November 17, 20204 yr by JHFIII

 Finally was able to check for ac noise today. DVM black lead to passenger side batt. Neg. And red DVM lead on charge post of alt. I got .000

Was the engine running? Typically all diodes give off just a little bit of noise. Like even my truck floats like 9mV to 11mV AC.

 

 

Yes it was running.

 I don't have a high end meter but I've used this one before when I did the WT ground mod and had a decent reading then. Thought maybe I forgot something this time. I'll have to try again I guess. I figured I should see setting, not all zeros.

Bad connection with probes or the wrong AC voltage level.

The meter I used auto ranges. I have another meter I will try. I also want to check voltage to the grid heaters to verify the relays are working properly. 

 I don't like to wait for problems to pop up in cold weather. Rather test and repair before there is an issue.

On 11/16/2020 at 4:48 AM, JAG1 said:

How much snow did you get ?

 

My wife and I just moved into our newly built house just 10 miles northwest of Baker City.  From @Mopar1973Man' place, it is 86 miles (compass heading 251 degrees) as the crow flies - much farther if you use the highway.  

 

Friday, November 13th - first round 8 inches

 

 

 

Sunday, November 15th. - second round 7 inches

 

 

Sunrise - yesterday morning

 

 

 

- John

Beautiful pics! I'm getting to the point though that I don't care for the cold so much.lol

 Checked my ac noise again with a different meter. I had .019-.023 fluctuation.

 

Nice pics Tractorman. Absolutely beautiful. That is a good place to be considering what's going on in more crowded areas these days. 

I miss snow. Always so quiet, and not to mention, picturesque. 

 

My philosophy is, you can always add another layer, you can only take so many off.

The pics are beautiful. I do like the snow as long as I dont work thru it. Down my way a snow storm is a delayed mud bath.

@JHFIII glad you got it all figured out! Your under hood is like a surgery room or 5 Star Hotel compared to mine, just beautiful.

Thanks for the photos those where good. 

@JHFIII clean wiring not like nasa rats nest. 

@Tractorman wow so much snow already, it's 70 in iowa today still sitting by the fire. Probably last nice weekend of that thought. Been really windy lately here.

On 11/19/2020 at 6:42 PM, Dieselfuture said:

Been really windy lately here

https://www.windbreaktrees.com/

As a southlander who visits Iowa and southern MN with some regularity, I ask when it's NOT really windy. Nebraska and the Dakotas don't do you all any favors... 

43 minutes ago, LorenS said:

https://www.windbreaktrees.com/

As a southlander who visits Iowa and southern MN with some regularity, I ask when it's NOT really windy. Nebraska and the Dakotas don't do you all any favors... 

Just seems that it's windy more often then I remember