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05-31-2010, 01:28 PM
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#1
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Junior Member
Fleetwood Owners Club
Join Date: May 2010
Location: Littleton, co
Posts: 19
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8.3 Cummins - low end power - gone!
This is our first coach and my very first post, so please be gentle!! We purchased a 1998 Monaco Windsor coach this spring and took it recently on a trip to Canada. On my way back, I noted some loss of power intermittently, and on return to Virginia, had a hard time getting any low end power at all. Changed the fuel filter, checked air filter, turbo spins but for some reason won't do anything in first gear, and under 1800 RPM. Above 1800 + 2nd gear and up, boost kicks in normally and acceration returns.
Thoughts?
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05-31-2010, 03:56 PM
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#2
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Senior Member
Country Coach Owners Club
Join Date: Jan 2006
Location: Northern California
Posts: 5,849
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Maybe check the exhaust brake for the butterfly valve opening in the exhaust pipe. Perhaps it is sticking a bit?
Put some high temp oil on the pivot points per the maintenance instructions.
__________________
Dean
1995 38' CC Magna #5280 **** Sold after 21 years of enjoyment.
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05-31-2010, 04:20 PM
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#3
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Junior Member
Fleetwood Owners Club
Join Date: May 2010
Location: Littleton, co
Posts: 19
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I noted last week that the PAC brake had actually seperated from the back of the turbo (clamp gone) and the butterfly valve was seized. I got it free and lubed it, but the air cylinder was also siezed, and I need to order a replacement. Opening the valve helped somewhat, but still having the low end issue. Thanks for the quick reply!
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05-31-2010, 04:48 PM
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#4
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Administrator in Memoriam
Appalachian Campers
Join Date: Jan 2000
Location: Buladean, NC
Posts: 8,126
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Does it build up boost? Maybe a hose is off or loose on the intercooler or turbo?
__________________
'11 GMC Acadia SLT AWD
'11 GMC Sierra 1500 4x4 Extended Cab
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06-01-2010, 07:52 AM
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#5
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Senior Member
Join Date: Apr 2003
Location: Oakton, Va
Posts: 1,160
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You indicate that the turbo spins, but do you know the turbo boost pressure? Perhaps you are equipped with a dash gauge for turbo boost pressure. If not I would get a Silverleaf VMSpc that plugs into your laptop to read out all of your engine and transmission parameters as well as codes. If you have an intermittent problem as you say you should see it in the engine parameters. Of course you want to avoid taking your MH to a shop and even if you do take it knowing as much as possible will help a lot. Don't be deterred by the cost of the VMSpc as it is nothing compared to the cost of a shop.You may be well tuned in to diesel performance, but remember that low RPM power and torque on a diesel is low, much lower than a gas engine. The diesel only excels when it is in its power and torque band.
__________________
Jim Walker
N Virginia
2014 Palazzo 33.2
Cummins 6.7 ISB, Allison 2100 6 Speed
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06-01-2010, 12:23 PM
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#6
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Senior Member
Join Date: Mar 2010
Location: Fowlerville, Mich.
Posts: 606
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Maybe transmission problems??? Are you starting out in first gear? Is the xmission starting in, maybe 3rd or 4th? Just a thought.
Greg
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06-02-2010, 10:05 AM
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#7
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Member
Join Date: Mar 2007
Posts: 80
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Is this Cummins a C8.3 or an ISC8.3
__________________
st687, 97 Foretravel U270
08 Saturn Vue
University of Parris Island class of 66
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06-22-2010, 12:54 AM
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#8
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Junior Member
Fleetwood Owners Club
Join Date: May 2010
Location: Littleton, co
Posts: 19
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It's the C8.3, and the turbo boost guage indicates very little boost in 1st, (<5lbs if at all) and 20+ lbs in 4th, 5th and 6th. We're going to have a look at it today, but thought a forum member might narrow the search for us.
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06-22-2010, 04:51 AM
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#9
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Member
Join Date: May 2009
Location: Parker Az
Posts: 99
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also check the air cleaner
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06-22-2010, 03:59 PM
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#10
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Senior Member
Appalachian Campers
Join Date: Sep 2002
Location: Dixie !! (north Georgia) USA
Posts: 4,113
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I agree with squeak.
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06-22-2010, 04:43 PM
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#11
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Member
Join Date: Mar 2007
Posts: 80
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low power
Check the inter cooler for cracks, have the lift pump checked for proper pressure, and check the return check valve on the injection pump, any of these can cause low power.
__________________
st687, 97 Foretravel U270
08 Saturn Vue
University of Parris Island class of 66
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06-22-2010, 09:09 PM
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#12
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Member
Join Date: May 2009
Location: Parker Az
Posts: 99
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ok so when was the last time you changed the air filter?
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06-23-2010, 12:44 AM
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#13
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Senior Member
Outdoors RV Owners Club
Join Date: Oct 2009
Location: Manitoba,Canada
Posts: 2,789
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Mine is the C8.3 Cummins,too. I don't get boost pressure in 1st gear either,so power in 1st gear is pretty lazy. But, once the revs are up enough for the shift to 2nd, the load increase on the engine increases the exhaust pressure enough to spin the turbo up and boost begins. On normal acceleration through the gears,if I'm pushing the pedal down, my boost will go up to about 20-22psi. On heavy loads up hills, it will go up to 25psi. I only saw it at 28psi once so far, and that was going up a 7%grade in 5th gear, engine @ 2100rpm, and putting out everything it had. I have a Banks Stinger system, so I suspect that the stock system might provide a maximum turbo boost of 24-26psi.
Your turbo is producing 20psi, so I suspect that the turbo itself is working O.K., but you may be losing some of the pressure in the pipes, hoses, or charged air cooler, on the way to the engine.
As the turbo is spun up by the exhaust, it moves air to the engine via the charged air cooler. It looks a lot like a radiator. There can be several rubber elbow connectors between the turbo and the cooler, they can cause trouble, cracked, or broken. The cooler itself can be cracked. A radiator shop or truck shop can pressure test it for you, some of the cracks can be repaired.
And if that exhaust brake is sticking it can cause intermittent loss of power. Once, I exhaust braked into traffic, then stepped on the accelerator, and the coach just sat there! No power at all! It took 2 or 3 minutes for the exhaust brake to decide to open and let me get some power.
__________________
2016 Creekside 23RKS
2012 Ram 2500 Laramie 4X4 Cummins 6.7L
Canada, eh?
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06-24-2010, 05:14 PM
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#14
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Junior Member
Fleetwood Owners Club
Join Date: May 2010
Location: Littleton, co
Posts: 19
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Well, 2nd day in the shop. My pac brake, still unhooked, gate is now wired in open position. Wastegate was siezed, we got that unsiezed yesterday, but unsure if actuator is working. Thats tomorrrows problem. What I am finding is these engines, while apparently reliable, are hard to trouble shoot. Anyone know the best place to buy a replacement turbo or even what model is on the C8.3 mechanical? Just in case.... we should have been off to Canada tonight......
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