Superduty

Kodiak owners C4500/c5500, etc are not happy with their Duramax engines. I'm shocked. I thought those would be nice little trucks.


http://dieselplace.com/forum/showthread.php?t=51108

"I can say that on long steep pulls once the Allison is into 3rd gear and screaming at 3000rpm it will maintain 45 mph. "

http://dieselplace.com/forum/forumdisplay.php?f=34

"Not to mention cost a fortune, in extra fuel. Above 70 mph, the 6.6 guzzles lots and lots of fuel. The happy place for fuel economy with these trucks is below 60. - Grossing 20,450 pounds this trip, I averaged 10 mpg, if I kept the speed down, but the wide open Texas roads made it unsafe to go slow - trucks roaring around at 70.. So my fuel economy went to a low of 7.4.. not good at $2.19 a gallon."

"Yep. Sure is ,I have the same problems as the light duty trucks. Runs hot on long grades towing. Temps up to and over 235*. I have done the stack seal.I am useing Evans coolant. A 0 pressure rad cap.No differance in over heating with the proper cap and 0 pressure cap. I am now looking into the t-stats. I can not pull the same weight with this truck as I could with my 02 ton truck. What a bummer."

"The last trip I made ,I relyed heavly on the exhaust brake becase of the terrain.When I got the delivery point I noticed heavy white smoke at idle damm lost another set of injectors.When I got home my wife reminded me ,the last time I made the same trip I lost a set of injectors.Ive got 32000 miles on this set, makes you think.LB7 NO MODS ANIMAL 4500 RVTRANSPORTER"

"You have to understand that it is a medium duty truck with a small duty truck motor. If you are pulling heavy, you will notice what I mean immediately.
Pay attention to the gear ratio that they offer. I have 5.13 and still get around 10MPG towing at the limit. Of course, the way you drive and the terrain you drive on, will make a differance."

Lots of interesting reading. These trucks need a high torque Cummins and some decent gearing, like 3:73 or so.

j-fox

Did he say he changed the radiator cap to a zero pressure? That only lowers the boiling point. Faulty thinking.

wannadiesel

Not if you're running Evans NPG coolant (as he mentioned). It's a zero pressure, high flow setup. If all he did was change the coolant and the cap, but not the water pump, then he's a

Geico266

If he could think he would have a CTD....

rammtuff

Sad when these trucks get 7.4 pulling 20k and a class 8 will get 6 pulling 80k

Luke S

I had one in 03'. I'd second everything they said. My all time low mpg was 6 going across Iowa at 65mph with a 10k load. If those truck had a Cummins with a 6-speed in em and air ride suspension they'd be decent. Even the Cummins would be a little small, but better than a D/A in my opinion. Large part of the problem was tranny programing, slightest incline and it would kick into 4th and sometimes 3rd and just sit there and scream. That was hell on mpg's.

blackdiesel

i pulled a log loader (converted to a tralier) back from oklahoma. empty i got 20 mpg on the trip out there and 7 on the way back

Superduty

The Cummins seemed to work pretty well in the FL60,70s when it was available. Now it is Mercedes only.

I knew a guy that hauled airplanes around the country. He had an FL70 single axle with a huge sleeper on it and a light tandem trailer, about 40 feet long. He had a 10 speed in the truck.

He put about half a million miles on that truck before the 12V Cummins cracked a head. He said the fuel economy was good.

He moved up to a bigger truck so that he could take bigger backhauls when he wasn't hauling airplanes.

suzukiZrider

anyone have any info on that duramax 7.8 is it the same as the isuzu engine or what

Superduty

Totally different engine. Somewhere between a Cummins ISB and ISC.

There is a post about it on the MD Duramax pages referenced above.

AAmeeting

Man I hate the people that chime in off topic and no nothing whatsoever on that site. Did you read all of the bs they gave that guy just for asking a question.

Jeff in TD

Good thread. Two things came to mind:

First, I really love DTR. No one launches off on a personal attack, even when you post about a problem. Also if you ask a specific question about a power upgrade or what not you are likely to get informative replies from people who know what they are talking about.

Second, I was kicking around getting a 5500 4x4 crew, and those links were really eye opening. I kind of figured they would be somewhat underpowered, but I didn't realize it would be that bad, or that they had problems that frequently.

By coincidence, my neighbor drives a C5500 2wd roll bed, and last night it had to be towed to the dealership. It would crank, but would only pump out smoke...

On the one hand, they are quite a bit cheaper than a Freightliner or what not, but on the other hand they appear to be a pickup drivetrain pushing a medium duty truck. Anyhow, I think I'll scratch the GM medium duty idea.

I just wish there was an option out there on 19.5's, with a medium duty size cab, in 4x4 from the factory, with a Cummins...

nickleinonen

that 6.6 shouldn't even be an option in the larger gm trucks when the 7.8 is avalable. same or better fuel economy under similar driving with a larger truck, and more torque..

surfram

A F650 crew cab or supercruizer w/cummins looks good to me compared to the chevy 5500 w/duracrap.

Superduty

"that 6.6 shouldn't even be an option in the larger gm trucks when the 7.8 is avalable. same or better fuel economy under similar driving with a larger truck, and more torque.."

Have you looked under the hood of those 4500/5500 trucks ? Packed and that is with a Duramax. It sits way up underneath the cowl. Terrible packaging. Only thing worse is a Hummer. No way they could put a 7.8 in there. No room.

I'll see if I can find a picture.

Check out these Kodiak recalls: http://rss-auto-recalls.justia.com/r...LET-KODIAK.xml