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Old 04-18-2017, 09:50 AM   #1
brian schuetta
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Default 2003 8.1 l 2500

Anybody have an opinion on these trucks? 130K, everything works, Allison trans, Dana rear, $6000. Has hail damage and there was a 5th wheel on it. Guy who has it just bought and says it has valve or lifter noise but in my opinion it's quiet and sounds normal. How many miles can you get out of these engines and what kind of mileage do they get?
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Old 04-18-2017, 11:34 AM   #2
Ed Wright
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Default Re: 2003 8.1 l 2500

Those things were a problem to get past EPA certification. A friend of mine is a GM Calibration Engineer, and worked on that deal. Power and gas mileage left on the table there. All in the computer.

I have not heard any complaints about durability. I had one in a motorhome. Thought it was fine. Had mine up to 8 mpg towing my race car, if I stayed under 70.
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Old 04-18-2017, 12:33 PM   #3
Dwight Southerland
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Default Re: 2003 8.1 l 2500

Brian -
I tried to respond to your PM but your email box is full.
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Old 04-18-2017, 01:16 PM   #4
Bob Don
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Default Re: 2003 8.1 l 2500

I have a 2002 2500 HD with 8.1/Allison. Runs great, tows great. I have found a minor rap when first starting cold but it goes away in about 30 seconds. It uses a quart of oil in about 3k miles. I get about 10 mpg towing a 24' enclosed with a 3700# car (about 8000# total).
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Old 04-18-2017, 02:49 PM   #5
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Default Re: 2003 8.1 l 2500

PM mailbox fixed.
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Old 04-18-2017, 02:55 PM   #6
brian schuetta
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Default Re: 2003 8.1 l 2500

I thought $6K was a good price for it. The owner says he's not comfortable with the noise he hears so it might be for sale again. It drives nice and you sure can feel the power. My other big block truck ( 1970, 3/4 ton, 402, TH400, Dana 60 4.11 ) is more of a museum piece now even with 83K miles. I really liked the new version BB and might wait for it to go up for sale again. So if you got a tune on that 8.1 there would be more mileage without hurting power?
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Old 04-18-2017, 03:15 PM   #7
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Default Re: 2003 8.1 l 2500

Helps power too. I got the biggest power gains from tuning those engines than any other. Mileage gains mostly come from simply taking less throttle to drive it.
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Old 04-22-2017, 12:38 AM   #8
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Default Re: 2003 8.1 l 2500

Last summer I bought a 2002 (Arkansas Truck) 3500 crew cab with 8.1 and Allison 1000 . It had 42,000 miles on it. I was told it was used a few times a year to pull a small trailer and race car. This thing is a cream puff and a super truck. Pulls the 45 Ft LQ 3 axel Eagle trailer with ease. It developed a miss and started to stall at times. It threw a code on the CPS and when I replaced it the mileage went up. It does have some VT noise when cold and a PS pump whine when cold. I probably paid a little much for it, but it was nice and what I wanted & kept me from spending my retirement on a brand new truck. I'm very pleased. I'm thinking about some sort of tuner and on the fly O2 monitor before I hit the road racing again.
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Old 04-22-2017, 09:12 AM   #9
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Default Re: 2003 8.1 l 2500

Adger, the hand held tuners you buy only alter the timing at WOT, or very high loads (like zero manifold vacuum) and usually only from about 1600 RPM & up. No part throttle timing tweaks, which is where you are towing that trailer down the highway. Timing is backed down at part throttle to lower HC emissions. That engine, and the 454" were tough to get past EPA certification.
Hand held tuners usually do lean WOT A/F also, since when they finally go into Power Enrichment, they are too rich from the factory. The throttle angle for P.E. mode, after the 60 second delay those & 454" come with, is set low enough that towing a heavy trailer in a head wind, or long grade, they will go into P.E. mode, meaning running down the road with an A/F ratio in the low 12-1 range. Mileage killer. Also, the Cat cool down mode is a mileage killer. When the ECU calculates the car's must be hot, it goes very rich to cool them down. It goes into that mode often when towing. Mileage killer.
If someone removed the cats, that needs shut off to save fuel. I just had a customer I picked up his 8100 truck 2 mpg driving, 4 mpg towing his travel trailer. Someone had removed his cats. :-) Those cool down parameters can be altered to improve mileage, when cats are still there.
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Old 04-22-2017, 10:27 AM   #10
Alan Roehrich
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Default Re: 2003 8.1 l 2500

My '03 only has 95K or so on it. Kevin's '02 is up over 200K.

Great engines, affordable to maintain, and even if anything happens to it, about half the cost to fix as any diesel.

My '03 is not for sale at any price.
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