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Well, it looks like a new alternator is in my very near future.
Friday my wife calls me at work to tell me the truck won't start. Cranks slow and won't catch. So she just stops and waits for me to get home with the other car.
I go out and buy a new Schumaker battery charger, clean all connections and check that they are solid and recharge the batteries separately. They both come up to 100% easily enough and the truck fires right up.
I drive it a couple of places over the weekend with no issues.
This morning I take it to work and about 1hr later when I am about 5 min from work I notice the lights seem a little dim. Look over and my voltmeter, (factory) is showing about 11v. Well crap. I park the truck, turn off the lights and the needle comes back up to about 13+.
So I figure a new alternator.
I was looking a the Duralast Gold for $223. Limited LIfetime warranty.
Go for it or recommendations for a local spot to buy a new one. I would wait to have one shipped but I need the truck fixed today so I will be picking it up today.
I don't run anything out of the ordinary so the usual 110amps should still be good for me.
If you can get one locally from a small starter/alternator rebuilder, that would be my first choice. If not, and since you need it today, the best bet is the parts store brands. Some fellas have had good luck with the 6.0 alternator from the Irish parts store. In my opinion, just go with your gut or who has what you need in stock. When you are in a time crunch, you need to get what will work now, not want you want that will work for years.
I had to do that with an AutoZoo steering gear. After we got back home, the gear was replaced with a second one since it was leaking from the shaft and it was under warranty. If/when the second AutoZoo gear fails, I will be going with a WTO or Blue Top gear.
@BillyBob69 This guy rebuilds then in Colorado Springs, been doing for a long time. He does a great job too. He may have a rebuilt one on the shelf already.
I would recommend the large case unit found on the 6.0s but that requires an adapter pigtail, not a big deal though, then a little grinding on the bottom of the mounting bracket. This is a 3G, large case maybe, 140 amps, more than the 110a OEMs. Mine will idle at 14+volts. Then have your OEM rebuilt for a backup. I carry both starter and alternator as backup when traveling.
Ok. Go the new alternator. Went with the Duralast Gold.
Recharged the batteries as on the way home, my dash meter dropped to 8v about 10 miles from home.
I checked voltage with engine running and it showed 11.7 on drivers side but only 9.7 on the passenger. So..pulled the old alternator and went and bought the new. After install both batteries were at 13.3 so I fired it up and checked voltage at the batteries. 12.7 on drivers, 12.5 on passenger. WTH. This is well after the GPSs shut off.
So I disconnected the batteries . Only thing connected is the grounds. Hooked up the meter and it shows 12.7 on both and holding.
So I am charging the batteries again only leaving it hooked up until they both show 100%.
I am concerned tho... what is with the odd voltages?
12.7 volts is pretty much fully charged on a lead acid battery, I doubt you'll see higher than that except for a short time just after removing the charger (surface charge which gives a false state of charge reading). Charging voltage is another story, should be about 14.1, but open circuit voltage is more like 12.7 (see chart, last column.
Ok. So batteries are holding good. I checked and tested and I finally checked the big bolt on the back of the new alt. 3.35v. Dammit... so I ran back to the parts store and swapped for another.... and now this one only shows .223v on the output of the alternator. WTH!!!! What are the chances that I got 2 bad alternators back to back?
Am I correct in that the large lug on the back or the alternator should be supplying 13+ volts?
I checked resistance from pos to pos and neg to neg. both were about 1.6 to 1.8 ohms. So I took apart the replacement ends on the drivers side and cleaned then real good and now resistance is down to .2 and .3 ohms.
still no joy. What am I missing? There isn’t something else telling the alternator what to supply, is there? I didn’t think these trucks were that electrically advanced when it comes to the charging system.
Ugh... Gotta get this truck back on the road.
HALP
@BillyBob69 This guy rebuilds then in Colorado Springs, been doing for a long time. He does a great job too. He may have a rebuilt one on the shelf already.
I heartily recommend Speedometer Service as well. Great bunch.
ok. So I sent an email to Rusty to see what he has on hand. This second one is going back tomorrow after work. Luckily the wife has already gone to the store for all her goodies so she is fine to play hermit tomorrow.
I would recommend the large case unit found on the 6.0s but that requires an adapter pigtail, not a big deal though, then a little grinding on the bottom of the mounting bracket. This is a 3G, large case maybe, 140 amps, more than the 110a OEMs. Mine will idle at 14+volts. Then have your OEM rebuilt for a backup. I carry both starter and alternator as backup when traveling.
Mine were direct plug-and-play without any adapters, just some modification to the bracket to fit.
My OEM alternators would hold around 14.0 VDC and dip to mid-13's VDC on a hot day towards the end (they did last over 200K miles in SoCal so not a bad run IMO). My new ones would hover around 14.3-14.4 VDC and dip to 14.0-14.1 VDC on a hot day under load.
SO Rusty got back to me via email and is saying there may be something wrong with the charging circuit. Well this is the first time I have had to troubleshoot it past a dead battery or alternator.
Terminals to the batteries are clean and solid.
I did check the ground on the passenger side to the motor and that is good.
Passenger side terminals are originals but very clean.
Where / what else should I be looking at? Where can it short out to cause this problem?
The cables all seem to be good. I am not getting any signal of a short between pos and neg.
Everything electrical works fine...other than this. No CEL. Starts and runs fine so long as the batteries are charged.
You need to check each of the major positive and negative connections and cables. Check them for continuity and resistance, not just a visual inspection.
There are ground connections on each side of the engine block toward the front behind the fan. Additional wiring is sometimes a good idea. If you add positive cabling, add negative cabling as well. Check the cable to the main fuse block, check the cable between the batteries, etc...
If this is the first time you are having to do anything other than replace batteries or alternator, a thorough inspection is due. Below is a link to my own personal effort to make my truck much more efficient regarding the charging system.
OK So I got to speak to Rusty and after a few minutes on the call, I contacted the parts store and they checked the first one I bought and it checks out good so.....
Rusty told me that the large wire on the back of the alternator is the feed from the batteries. And that it should have the same voltage as the batteries do. But it does not so....Where does that wire route to? Or is it going thru a relay?
Anyone got the charging system wiring?
You need to check each of the major positive and negative connections and cables. Check them for continuity and resistance, not just a visual inspection.
There are ground connections on each side of the engine block toward the front behind the fan. Additional wiring is sometimes a good idea. If you add positive cabling, add negative cabling as well. Check the cable to the main fuse block, check the cable between the batteries, etc...
If this is the first time you are having to do anything other than replace batteries or alternator, a thorough inspection is due. Below is a link to my own personal effort to make my truck much more efficient regarding the charging system.
