Cranking voltage

thomasinnv · May 30, 2018, 12:00:08 PM

So I've been having an intermittent problem with starting the bus. Thought I had it handled, since it didn't rear it's ugly head for a few weeks. When i push the start button (on the dash or in the rear makes no difference) sometimes I get a "click click click click" on and on with dash lights flashing everytime it clicks. First thing I did was disconnect and inspect all battery cable connections from batteries to starter and everything in between, clean and reinstall. A few days later, same problem. I replaced the starter solenoid in the rear junction box just for good measure, and cleaned the connection to tje solenoid at the starter, which was loose. All seemed good in the world again until yesterday. This time I went to the rear and jumped the starter solenoid and no more clickety click, but the first revolution of the starter was very slow then it started spinning normally.

I had my wife watch the voltage meter that reads directly from the batteries while I was cranking it and it dropped as low as 18.5 while cranking, seems way to low to me. I suspect tired batteries so I have them shut off now with the maintainer disconnected, going to let them set overnight and do a load test. I suspect that they will fail, but just for knowledge sake, does anyone know what the lowest acceptable cranking voltage is? Series 60 12.7.

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luvrbus · May 30, 2018, 12:25:03 PM

What starter is on the bus ?,a 24 volt system Delco shouldn't have more than 1 volt drop when starting,the 12 volt system is a 1/2 of a volt, I would say it is battery time

thomasinnv · May 30, 2018, 12:41:54 PM

Quote from: luvrbus on May 30, 2018, 12:25:03 PM
What starter is on the bus ?,a 24 volt system Delco shouldn't have more than 1 volt drop when starting,the volt system is a 1/2 of a volt, I would say it is battery time

It's the big heavy sucker.

I'm leaning towards batteries too. These 8D are over 4 years old and i realize a lot of guys never get that long a life from the 8d. I have a maintainer that runs on them is probably the only reason they lasted this long. I have a suspicion that the shop that did the engine swap probably didn't help the issue any, there was talk about trouble getting it primed so most likely they ran the batteries into the ground trying to get it started. Problem first appeared right after I got it back from the shop.

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daddysgirl · May 30, 2018, 12:59:58 PM

Hi all!
You will know far more about this than I...but if the 8D's are going bad with a 40 or 42 MT (or similar) the batteries will kill the starter. Been there...done that.
And your bus is different from mine, so I don't know if checking the shifter to make sure it's in neutral will matter. Anyhoo...just wanted to say hi, and give you the info you all gave me a couple of years back

HB of CJ · May 30, 2018, 01:00:54 PM

Respectfully ...

I know this has been beaten to death here but have you checked and cleaned your battery cable posts? Hidden corrosion can also suck down the cranking voltage.

Cranking voltage and amperage are related. Might be time for new battery cables? Twenty four volts should markedly reduced the need for heavy cables gage.

But ... cables are kinda cheap compared to other Bus Conversion repairs. Consider just imagining the system is 12VDC and run cables to suit? Very low voltage drop.

Can you bump/push start the Coach?

Respectfully ...

luvrbus · May 30, 2018, 01:16:52 PM

You probably have the 42MT Delco they take some amps and voltage,yours may have the low voltage protection device also since your engine is a DDEC that will keep it from engaging lol save your money and get a MT39 Delco starter

thomasinnv · May 30, 2018, 01:23:17 PM

Quote from: HB of CJ on May 30, 2018, 01:00:54 PM
Respectfully ...

I know this has been beaten to death here but have you checked and cleaned your battery cable posts? Hidden corrosion can also suck down the cranking voltage.

Cranking voltage and amperage are related. Might be time for new battery cables? Twenty four volts should markedly reduced the need for heavy cables gage.

But ... cables are kinda cheap compared to other Bus Conversion repairs. Consider just imagining the system is 12VDC and run cables to suit? Very low voltage drop.

Can you bump/push start the Coach?

Respectfully ...

See the op, first thing I did was go through all the cables and connections.

When the trouble does pop up (extremely intermittent, when it does happen it is always a cold start in the morning, never happens on a hot start) it will only click when using the button, and every click moves the engine over just a bit. If I jump the solenoid at the starter it will crank every time albeit very slow for the first revolution. This is what is making me suspect the batteries, that and thier age. I suspect by the way it acts that the voltage is dropping enough that the relay or the triple function device is dropping out, and when the starter disengages the voltage raises enough to re-engage the rrlay or triple function, thus re-engaging the starter and repeat.

I will have a definitive answer on the batteries in the morning.

Napa has 1400cca 8D with 30 mo warranty for 225. Best price I can find where I'm at.

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daddysgirl · May 30, 2018, 01:28:34 PM

Any starter that doesn't weigh more than I used to...is a good thing. I have a brand new 40. Nice, shiny and heavy. I was going to get the 39, but I couldn't resist the sale for the 40 at $150.00, and I'll get to rebuild the old one...if I ever get around to finishing it.
BTW...just a question, but doesn't the regulator effect that newer circuit as well? Or is it built in? I know nothing of newer engines.

luvrbus · May 30, 2018, 01:30:24 PM

That is a good warranty 3 years, I can buy the 8-D for a 185 bucks ea but they come with a 1 year warranty,I would go for the $225.00 with the 3 years myself

thomasinnv · May 30, 2018, 01:33:30 PM

Quote from: daddysgirl on May 30, 2018, 01:28:34 PM
Any starter that doesn't weigh more than I used to...is a good thing. I have a brand new 40. Nice, shiny and heavy. I was going to get the 39, but I couldn't resist the sale for the 40 at $150.00, and I'll get to rebuild the old one...if I ever get around to finishing it.
BTW...just a question, but doesn't the regulator effect that newer circuit as well? Or is it built in? I know nothing of newer engines.

Regulator does nothing for starting, only controls charging voltage while running.

And before anyone asks, yes it is charging as expected. I also have a maintainer that runs 24/7.

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thomasinnv · May 30, 2018, 01:35:26 PM

Quote from: luvrbus on May 30, 2018, 01:30:24 PM
That is a good warranty 3 years, I can buy the 8-D for a 185 bucks ea but they come with a 1 year warranty,I would go for the $225.00 with the 3 years myself

6 mo free replacement with 30 mo prorated. I'm in Mcalester OK, not a lot of options here.

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luvrbus · May 30, 2018, 01:38:46 PM

Check with the John Deere dealer there

thomasinnv · May 30, 2018, 01:44:18 PM

Quote from: luvrbus on May 30, 2018, 01:38:46 PM
Check with the John Deere dealer there

They don't carry them. Neither does the equipment shop or the truck shop. Seems just about everything uses 31's now. Been there done that, won't do it again.

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luvrbus · May 30, 2018, 01:54:17 PM

Is there a Battery and Bulbs Plus there I haven't been there since 2000 when I built the Ford Dealership

thomasinnv · May 30, 2018, 02:13:25 PM

Quote from: luvrbus on May 30, 2018, 01:54:17 PM
Is there a Battery and Bulbs Plus there I haven't been there since 2000 when I built the Ford Dealership

Nope. That was the first place I looked for.

I couldn't stand it anymore so I had to go test them batteries lol. (Never was good at waiting). One tested good at 1410cca, the other failed miserably at 735. (They are rated 1400cca) Not gonna get any better setting overnight so a new set of batteries it is. Might as well just set my wallet on fire and be done with it. Oh the joys of bus ownership.

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