Cranking voltage '04 F250 6.0 PSD

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D60

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Had a weird no-start yesterday on a client's '04 F250. Was cranking really slow, and this was after a ~50 mile drive.

I isolated the batts and each reads about 12.7V after sitting overnight. I load tested each and they come in on the low end of the "good" zone but still in the green.

During cranking (after glow plug light) the lowest voltage is 10.59 -- this strikes me as low but I've never really looked at minimum voltage during cranking on any other vehicle, much less an oil burner.

Both batts are Duracell 65AGMs with 750 CCA and date stickers of 6/23 and 7/23. I also wonder if this should have AGMs??

@bdcardinal
 
Did AGM exist in 2004? Even if the answer is no, I'm under the impression that it's an acceptable upgrade for those chasing longer battery life.

>10V starting is fine. I did a battery test on my car yesterday and starting voltage was under 10.

It probably didn't fire injectors if it was cranking too low to make minimum HP oil pressure. Sounds like a fluke start.

My Cummins 6.7 is probably looking at its last winter on 2018 date coded NAPA Legends (a 2 year warranty battery) in 94r size. Jump pack lives in the truck at this point.
 
I've regularly measured the cranking voltage on some of my vehicles, and it tends to be 10.5 to 11.0 V in warm weather with a pretty fresh battery. An engine should crank pretty quickly even at 10.0 V unless the engine is extremely cold.

When you measured the cranking voltage of 10.59 V, was the engine cranking really slowly at that time? Or only during previous cranking? It should crank fine at that voltage. Maybe it's an intermittent issue (poor battery connections?).

Also, you shouldn't measure the minimum voltage (i.e. don't just set your multimeter to the MIN setting). You should look at the average voltage while the engine is cranking. It's normal for the voltage to dip down to 8 or 9 volts for a fraction of a second even if the battery is good, and that reading is irrelevant.
 
johnmyster said:
Did AGM exist in 2004? Even if the answer is no, I'm under the impression that it's an acceptable upgrade for those chasing longer battery life.

>10V starting is fine. I did a battery test on my car yesterday and starting voltage was under 10.

It probably didn't fire injectors if it was cranking too low to make minimum HP oil pressure. Sounds like a fluke start.

My Cummins 6.7 is probably looking at its last winter on 2018 date coded NAPA Legends (a 2 year warranty battery) in 94r size. Jump pack lives in the truck at this point.
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Optimas did and they're AGM AFAIK
 
twX said:
I've regularly measured the cranking voltage on some of my vehicles, and it tends to be 10.5 to 11.0 V in warm weather with a pretty fresh battery. An engine should crank pretty quickly even at 10.0 V unless the engine is extremely cold.

When you measured the cranking voltage of 10.59 V, was the engine cranking really slowly at that time? Or only during previous cranking? It should crank fine at that voltage. Maybe it's an intermittent issue (poor battery connections?).

Also, you shouldn't measure the minimum voltage (i.e. don't just set your multimeter to the MIN setting). You should look at the average voltage while the engine is cranking. It's normal for the voltage to dip down to 8 or 9 volts for a fraction of a second even if the battery is good, and that reading is irrelevant.
Click to expand...
Nah, at 10.59 minimum it cranks "ok". It sounds labored to me but not excessively slow. And yeah, that's the MIN as recorded by my Snappy DMM.

I'm also thinking a battery cable(s) as yesterday it started itself after sitting for a couple minutes.

Around Post #18 here TMT gets jiggy with analyzing current flow in the 6.0 system. I honestly haven't dug into it enough to see what that might mean for this situation. Since it's fine NOW it's effectively an intermittent problem and battery cables aren't cheap for this application. Even build-it-yourself wouldn't be that inexpensive at today's prices.
https://www.powerstroke.org/threads...o-huge-for-what-reason.1394982/?nested_view=1
 
Look at the cable connections at the starter. The cables can corrode inside the insulation at the connection points. Could even be a starter wearing out, which is not uncommon. My 7.3 leaks enough to keep the connections corrosion free, but the oil will eventually kill the starter too.

AGMs were around back then but not OEM on these trucks.
 
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crashz said:
Look at the cable connections at the starter. The cables can corrode inside the insulation at the connection points. Could even be a starter wearing out, which is not uncommon. My 7.3 leaks enough to keep the connections corrosion free, but the oil will eventually kill the starter too.

AGMs were around back then but not OEM on these trucks.
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Excellent point. The positive crossover that runs above the rad isn't great, but I cut the insulation back and the corrosion is mild and doesn't go more than maybe 2" up into the insulation.

If it were reasonable I'd just replace that cable because I don't think treating corroded cables as PM is absurd --- but @bdcardinal was kind enough to help me learn it retails for $400 to $700, which I mention because it's amusing.

Yes, there are aftermarket places building cables for somewhat less and/or we could source tinned marine cable and build something up. But keep in mind as this is for a customer I should mark up parts and charge for my time at which point prefab aftermarket starts to look more attractive. Anyway for the time being I'll keep looking for more obvious smoking (hopefully not literally) guns in the system and forego the absurdly expensive cable ;)
 
D60 said:
Yes, there are aftermarket places building cables for somewhat less and/or we could source tinned marine cable and build something up. But keep in mind as this is for a customer I should mark up parts and charge for my time at which point prefab aftermarket starts to look more attractive. Anyway for the time being I'll keep looking for more obvious smoking (hopefully not literally) guns in the system and forego the absurdly expensive cable ;)
Click to expand...
I'd check the voltage drop between battery and starter by connecting one lead to the positive battery terminal and the other to the positive connection at the starter. I'd expect this voltage to be well under half a volt while cranking the engine.

Then do the same between the negative terminal and a grounded point on the starter or engine. If this reading is high, do the same between battery negative and chassis ground to rule out a bad battery-chassis ground, since the ground path to the engine might go through the chassis.
 
starter is shot. very common that one motor brush will burn thru at their connector or the commutator get carboned up and has too much resistence.
 
I put group 65 in my one 96 Cummins, instead of the group. 27. They were more available and at lower costs, the footprint was the same and the height was just a bit off.

After a couple years they do seem to crank slower than old group 27. Anecdotal for sure, but the 65 just don’t seem as good.

Don’t know if older group 65 have a design attribute that affects cranking, even if the voltage looks ok?

10.59 v isn’t the worst, after all, the engine probably has an afterglow function, so is probably seeing decent load beyond just cranking…
 
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