Author Topic: 2004 c12 high load bucking, what now  (Read 2473 times)

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Offline cmac

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2004 c12 high load bucking, what now
« on: March 31, 2017, 08:43:57 PM »
I'm a new owner of a 2004 Beaver Patriot Thunder C12 with 505 hp.  This is the chain of evens to my current situation.  Picked the motorhome up in Texas to drive to Michigan. Within a 100 miles the voltage, from the Aladdin, started to drop.  Driving down the road tried to start the gen, it would not start.  I thought is would not start because the fuel level was near 1/4.  Before we get the the truck stop the voltage dropped all the way to 9.4v! During that time the transmission light came on and the down shifts became hard.  Filled up and stayed the night at the truck stop, started out the next day.  Checked the alternator output at idle, 12.2 volts. .  Sam's determined the chassis batteries were bad, purchased two and installed.  Back On the road without running the gen the voltage was dropping again.  From that point on I ran the gen to keep the voltage about 12 volts.  However, it started bucking at 90% load in 5th and 6th gear.  This continued to get worse as I drove.  Hind sight, I should have found a Cat service center.  Instead I drove on, by the time a arrived in Michigan I was limited to 70% load in 5 and 6.  And had to back off the throttle to keep it from bucking. To me it seems like fuel delivery or, did the low voltage fry something in the ECM?  I plan to,start by changing the fuel filters, not sure how old the fuel in the tank was sitting.  Also, it could have been sitting with a mostly empty tank.  The motorhome has 90k miles, service records look good.  Ideas?

Offline Brett Wolfe

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Re: 2004 c12 high load bucking, what now
« Reply #1 on: April 01, 2017, 05:55:21 AM »
cmac,

Welcome to the Diesel RV Club.

Quite possibly two separate issues.

You said, " From that point on I ran the gen to keep the voltage about 12 volts." And, "Checked the alternator output at idle, 12.2 volts"

Both statements indicate an electrical problem.  The alternator should be charging at 13.5-14.0 VDC. Also, many coaches are not set up to charge the CHASSIS battery from the inverter/charger when it is powered by the generator or shore power.  You will need to verify that your is. Again, a voltage reading of "about 12 VDC" indicated a problem.

Particularly if you do not know the coach's service history, absolutely change both fuel filters. That is virtually always the first step when you have power issues at higher fuel demand rates (like when at full throttle).

Let us know what you find.


Offline cmac

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Re: 2004 c12 high load bucking, what now
« Reply #2 on: April 01, 2017, 08:28:10 AM »
Thanks, I will try the filters and pickup an altenator.  Work is interferring with life right now but I will post results and I'm sure more questions.


Offline WILDEBILL308

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Re: 2004 c12 high load bucking, what now
« Reply #3 on: April 02, 2017, 07:10:14 PM »
I agree with Brett. The first thing is change the fuel filters. I would look for water in the separater to.
Let us know what you find on the electrical problem.
Bill
2003 Bounder 38N,300 HP 5.9 Cummins
Allison 3000MH Trans.Towing 2014 Honda CRV. Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

Offline cmac

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Re: 2004 c12 high load bucking, what now
« Reply #4 on: April 09, 2017, 05:17:07 PM »
Good news, changed both fuel filters.  And the motorhome has the power back.

Thanks for the help, I will be asking more question in the future.

Offline cmac

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Re: 2004 c12 high load bucking, what now
« Reply #5 on: April 09, 2017, 05:24:50 PM »
Also, after my original post I decided to have the alternator tested.  Opened the engine hatch to find the the serpentine belt was gone!  Pulled the alternator and the, shredded belt, found the the last person beat the Pulley on to the shaft.  To the point that the Pulley had split and I'm sure cut the edge of the belt.  New idea here, if the key way does not line up use a bigger hammer. The Alt was bad, bought a remanufactured alt, new pulley, two bearing for the rough idler pulley and a belt.  Went back on and the volts are running in the mid to upper 13s at idle. And the bearing is not growling, just hear the cat purring.