03 Chevy 2500HD 8.1/Allison

matthies · Mar 17, 2017

Anybody have one or ran one and what do you think. Can't justify the diesel option, but like Allisons in the dump trucks at work.

rustyfarmall · Mar 17, 2017

I owna 2001 K3500 with the 8.1 and a 6 speed manual. It gets the job done and never breaks a sweat.

Bobl1958 · Mar 17, 2017

I had an '03 Duramax with the Allison. Great combination. You would love it. Mine would consistently get 22mpg on the highway if I kept it below 70mph. With no trailer of course. Seemed to hover around 12-13 with a trailer.

The only issue I had with mine was the injectors. Had to put a full set in at the dealership at 105K. At 120K one of the new ones went bad. I took it to a local diesel shop that works on my farm eqt. They said just replace the bad one. At 125K a second one went bad. I sent it down the road..but I did like that truck.

Dennis(IA) · Mar 17, 2017

Had an '04 years ago, liked it. Pulled a 5th wheel to the east coast and back one winter it worked great, but you better find a gas station at 200 miles. Sold it because I did not need it and it took up too much room in the pole building. It was an extended cab and 8 ft box, darn nice truck.

rbhuntn · Mar 17, 2017

I have that exact truck. 2003 8.1 with the 5 speed Allison. 4x4 Ext cab with 8 foot box.

I bought mine used about 4 or 5 years back with 58K miles. Has over 128K miles now. So far been a good truck. Uses a little oil like all of the 8.1's but nothing major.

Use my to tow bumper pull and gooseneck trailers with on a regular basis. Pulls like a fright train almost.

Mine has the 3.76 gearing in the diff's. Empty running at 70 on the hwy for I can get about 300 miles on 3/4 a tank which equates to about 14mpg. When towing through the Ozarks with a light load on a bumper pull I get about 10 to 12 mpg. With the gooseneck loaded heavy (about 12.5K including trailer) I get about 8 mpg.

On more level road the light loads about 12mpg and the heavy loads about 10 mpg.

Only real issues that i have had to fix are:

Leak at rear seal in xfer case

Dash went out and dealer had to flash the microcode (was a no cost fix)

Front wheel bearings at 90K

Wiring control block at back of truck went bad. Think that may have been my fault after driving through some brush one day.

Total cost of repairs to date about $3,500. Some of that was labor when I had the dealer fix the wheel bearings and leak on xfer case. Work was real busy and I didn't have the time to do these myself.

Make sure that you check and replace if necessary the front and rear shocks. If these are worn the truck rides really funny and makes strange noises.

For tires I am running the Firestone TransForce AT's and they are holding up real well.

Hope all of this helps

rustyfarmall · Mar 17, 2017

(quoted from post at 08:39:20 03/17/17)
I have that exact truck. 2003 8.1 with the 5 speed Allison. 4x4 Ext cab with 8 foot box.

I bought mine used about 4 or 5 years back with 58K miles. Has over 128K miles now. So far been a good truck. Uses a little oil like all of the 8.1's but nothing major.

Use my to tow bumper pull and gooseneck trailers with on a regular basis. Pulls like a fright train almost.

Mine has the 3.76 gearing in the diff's. Empty running at 70 on the hwy for I can get about 300 miles on 3/4 a tank which equates to about 14mpg. When towing through the Ozarks with a light load on a bumper pull I get about 10 to 12 mpg. With the gooseneck loaded heavy (about 12.5K including trailer) I get about 8 mpg.

On more level road the light loads about 12mpg and the heavy loads about 10 mpg.

Only real issues that i have had to fix are:

Leak at rear seal in xfer case

Dash went out and dealer had to flash the microcode (was a no cost fix)

Front wheel bearings at 90K

Wiring control block at back of truck went bad. Think that may have been my fault after driving through some brush one day.

Total cost of repairs to date about $3,500. Some of that was labor when I had the dealer fix the wheel bearings and leak on xfer case. Work was real busy and I didn't have the time to do these myself.

Make sure that you check and replace if necessary the front and rear shocks. If these are worn the truck rides really funny and makes strange noises.

For tires I am running the Firestone TransForce AT's and they are holding up real well.

Hope all of this helps

My '01 dually has the 4.11 gears. Fuel mileage is similar to yours. Most often it ranges from 10 to 12. Empty or towing a trailer doesn't seem to matter. The lowest ever was 8, and the highest was about 13.7

Tim in OR · Mar 18, 2017

I own an 02 w/duramax and Allison. I have 255,000 miles on it and its still going strong. The only problem I had with the transmission was when it went to limp mode (forward was limited to 3rd gear). Turned out the switch on the side that talked to the computer went bad. Seems like $39.00 bought a new one, easy fix.
I like the combination so much, I am waiting on delivery of my new one. The old one will take over the duties of my 69 GMC PU.
Tim in OR

03 Chevy 2500HD 8.1/Allison

matthies

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rustyfarmall

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Bobl1958

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Dennis(IA)

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rbhuntn

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rustyfarmall

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Tim in OR

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