New battery, alternator, new starter - Voltage drops then engine dies

MikeandMoon · November 24, 2019, 11:05 AM

Ok, so all that new, truck will start the first time no prob, after high idle settles down, truck stalls, then won't start. Battery voltage drops to around 10v and can't crank the starter.
HELP PLEASE

Froggy1936 · November 24, 2019, 01:55 PM

Chevy starters are notorious for failing when hot , I would just replace it with a modern Hi Torque Starter (they are less susceptible to heat, and smaller) Make sure you disconnect all the batteries as starting and house batteries are attached to the starter ! Frank

Rickf1985 · November 24, 2019, 08:37 PM

While I might agree with Frank I would like to see you do a bit of diagnosing before throwing any more parts at it. When it is running have you checked the voltage at the chassis battery with a meter? It should be showing 13.5-14.5 volts. Did you remove and clean the ground cable where it attaches to the frame? And are the ends that attach to the battery in good condition and clean? If the voltage is dropping to ten volts while it is running it will stall because the electronic module needs that much to run. If it is not charging at the voltage I mentioned make sure the two wire plug for the alternator is plugged in at the back of the unit usually on the side at the rear. If it is and it is still not charging then check for voltage with the engine off at the large red wire at the back of the alternator, if not voltage then the fusible link has blown down at the starter for that wire. You did hook that wire back up right?

MikeandMoon · December 07, 2019, 03:37 PM

Thank you for your input, yes to all the items, mentioned. Ran like a beast!!! For about 20 miles, backfired, started running a little rough, now here's the kicker, accelerating from real slow or a dead stop, I watched the voltmeter drop to almost 0, almost stalled out but engaged the "dual" feature which is supposed to charge the house batteries while running so I was able to make it home. But now we are absolutely stumped!

Froggy1936 · December 07, 2019, 04:08 PM

Sounds like no elec power, Check all connections esp at batt & starter, A bad ground or cable, And last but not unheard of a bad new battery !

Rickf1985 · December 07, 2019, 04:29 PM

The alternator should have kept it running even with a bad battery. It is not charging, have you taken the alternator in to have it checked? If it is good then I still say it is one of the fusible links down by the starter. Most likely the one on the alternator wire. Now, with that said, does your alternator charge through a dual charging setup? Not the Aux switch. It would be a rectangular box with three terminals on top. One terminal from the alternator and one each to the chassis battery and the other to the house batteries. Sometimes people add these into the system. If it has that then that may have gone bad if the alternator and the fusible link check out good.

MikeandMoon · December 07, 2019, 06:40 PM

Thanks, no it only charges when the dual is engaged. I do know what you meant tho, my Mitchell had that setup. This unit also has the momentary switch as well, so if my crank is dead the house can be pulled from to strat the engine. Here again another quirk, when running it shows voltage at 14+ so the alternator is doing its job, only I stopped looking at the voltmeter after 5 miles or so. So I don't how long it started to drop in volts before I saw it was almost at 0. Like I said earlier, I don't know why it backfired, but that's when I noticed it running kinda rough. Before she was purring like a kitten. It only has 28,006 miles, and d maintained very well up until it was parked, in 1998. 🤨

Rickf1985 · December 07, 2019, 09:17 PM

It probably backfired because it was losing spark due to low voltage. If it went dead while driving then either the alternator went out or you have a major short or the fusible link went. Last possible thing is the two wire plug came out of the back of the alternator and that would cause a no charge scenario. With it not running you should show the battery voltage on the charging wire at the alternator, if not something is bad in that wire. I understand the momentary switch, most Winnebagos have that. But that is not going to change the way the alternator charges. All that switch does is connect the batteries from the coach to the battery on the chassis through a relay. Nothing else is changed. Just connection the batteries together. Now, if the battery shorted out internally it is possible that it took the alternator with it and that is why it ran for a while before dying. It went to max charge and fried.

MikeandMoon · December 09, 2019, 08:19 PM

Omg, electrical blows my brain, went thru and traced every wire, checked all the connections, had alternator tested, v starter as well, and now the new truck it had learned is, the volt meter starts dropping in voltage and truck stats to run like shoot, only when I'm in gear and I'm am accelerating, of I take my got off the gas it's settles back to normal. Huh? It's such a great engine and unit, I don't want to give up but we can't think of anything else. Thanks so much for any other ideas you might have.

tmsnyder · December 10, 2019, 07:52 AM

It's going to be something simple.

Did you check the ground cable? I know it cranks so it has a decent ground but worth checking. Especially with something changing once torque is on the motor, maybe it's loosing ground.

Also, can you disconnect the house 12V from this and just run it in its simplest form? Just run the chassis system until this is straightened out.

LJ-TJ · December 10, 2019, 11:35 AM

Hm? Hang tough Mate we've all been there. Trust me persistance will pay off.

and you'll be sooooooo !@#$%^&*( when you find it be cause it will be something so simple. D:oH!

Rickf1985 · December 10, 2019, 03:52 PM

Is the alternator belt tight and not work out? If it is tight but sitting down inside the groove instead of up at the top of the groove then it is probably slipping at higher rpms. It will be riding on the bottom of the pulleys instead of the sides and that is why a very worn belt will not squeal. It is worn beyond the squealing point.

MikeandMoon · December 12, 2019, 12:42 PM

FOUND IT!! The positive wire from the battery to the started had shifted and was on the drive shaft. That explains why it only would mess up when I was in gear. It melted the casing and exposed wire was touching the drive shaft. Thanks everyone!!

Rickf1985 · December 12, 2019, 07:19 PM

Glad you found it but that had to be putting a hurting on a bearing at one end or the other of the driveline. Hopefully the rear end since that is a lot more robust than the transmission!

tmsnyder · December 13, 2019, 09:52 AM

What wire could be back at the driveshaft?

There's a neutral safety switch and a reverse light in the vicinity, but it can't be the battery wire can it?

Elandan2 · December 13, 2019, 02:32 PM

Sure, it's a class A, the battery compartment is probably partway back on the passenger side or else under the entry step. Winnebago puts both chassis and coach batteries in the same compartment.

Rickf1985 · December 13, 2019, 04:12 PM

My chassis battery is righ behind the front bumper, I know because I just had to fight the dead hunk of heavy lead out of there a couple hours ago! My house batteries are in a compartment right behind the passenger tire. But I have seen many, many units with the batteries under the entrance step and the battery cables loosely strung all over under the coach.

DaveVA78Chieftain · December 13, 2019, 07:52 PM

My 78 Chieftain had the battery compartment about 10ft aft of the drivers seat. Cable ran up the frame rail to the the starter solenoid under the drivers seat. I had the engine battery and four marine batteries in that battery space.