Duramax

[CBlack]

Made a trip with the in-laws to the southern edge of the Smoky's this past week. We followed my FIL as he towed his 43' MobileScout toy hauler with his 2006 Chevy 3500. There were anywhere from 6-10% grades throughout the the last leg.



I had always thought the Duramax as a fairly decent engine, but all of my experience has been on relatively flat terrain.



That thing was a dog on every steep grade it pulled. Now, I know they've changed it up since that MY, but the changes haven't been that drastic from what I gather.



I don't know if he doesn't really know how to drive it (he claims it has an OEM exhaust brake, and it doesn't) or what, but it was not anything like the magazines "claim. "



On the way home, it was around 105 degrees and his alarms in his truck went ape**** as his transmission hit 300 degrees from the ups and downs.



Yet he continues to say he won't buy a Ram because "it falls apart" around the power train.





Duradud is a fitting term.

 

[HBarlow]

Yep, some folks stopped learning anything new when they were about 16 years of age. They learned all the wrong information and false rumors they wanted to know back then and have stubbornly held on to them all these years. Many are brand loyal to the labor union GM junk or Furds, just like political parties, and no facts are going to influence them.

I posted years ago about pulling from IL to Sioux Falls, SD with another transporter with a brand new '05 or '06 Duradud when I was still driving my '01 Ram 3500 HO/six speed with over 300k miles. The GM was following me and would fall back on every grade pulling a lighter trailer. I was in touch with the other transporter on the CB. I was holding my old Dodge in sixth gear with 3. 54 gears and letting it pull down to 1600 rpm and the GM, with an automatic, was falling behind until the Allison forced a downshift to direct and revved the engine up to 2600 to 2800 rpm where it produces torque.

Duraduds are faster from stop light to stoplight but failures pulling heavy trailers in the hills. Ditto Furds.

 

[seafish]

You have just described one of the major differences between the I6 Cummins and ANY other V8 diesel engine-- no matter how "great" a engine it is... low end torque "by engineering design" gives the CTD a marked advantage on pulling grades with a load. Of course, on flat terrain that advantage might disappear, but then there are the other advantages of the CTD, like longevity and relative ease of service.



None of these advantages speak to the quality of the truck surrounding the engine, but that tends to be improving year by year with ALL of the brands. Plus I personally would rather have a truck that can pull a hill loaded to the gills rather then an expensive grocery getter that is comfortable, but overheats or breaks down under load. Just stirring the pot here... :-laf None of this is to say that Chrysler could't have done a MUCH better job designing the front ends on the earlier 4x4 trucks, but that is also now someting that they are FINALLY taking care of.

 

[MChrist]

Well, I don't know what model of Duramax I have in our '07 GMC 5500 at work, but we just don't experience any of the problems you guys talk about. It's rated at 300/520 ish and a 5 speed Allison. Truck weighs right around 15,000 empty (and is never empty) and we often hook up our 12,400 restroom trailer to it. It pulls it right along, nicely, quietly, never overheats, and has been completely trouble free.

Our area is relatively flat, but there is a 7% grade about 3/4 mile long near us, and with the cruise set at 55, rpms around 1700 (if I recall correctly) she doesn't even feel it and doesn't downshift.

Maybe I am one of the lucky ones?

Truck is bone stock. . maybe that's why?

 

[Wingate]

Well, I don't know what model of Duramax I have in our '07 GMC 5500 at work, but we just don't experience any of the problems you guys talk about. It's rated at 300/520 ish and a 5 speed Allison. Truck weighs right around 15,000 empty (and is never empty) and we often hook up our 12,400 restroom trailer to it. It pulls it right along, nicely, quietly, never overheats, and has been completely trouble free.

Our area is relatively flat, but there is a 7% grade about 3/4 mile long near us, and with the cruise set at 55, rpms around 1700 (if I recall correctly) she doesn't even feel it and doesn't downshift.

Maybe I am one of the lucky ones?

Truck is bone stock. . maybe that's why?

4:88 or 5:33 gearing??? All of our 4500 had the 4:88, but we had two 5500 that had 5:33 gears. .

 

[RustyJC]

We followed my FIL as he towed his 43' MobileScout toy hauler with his 2006 Chevy 3500.

I can only imagine how much that truck was operating above its GCWR. No wonder the cooling system couldn't keep up with high ambient temperatures and steep grades.



Rusty

 

[rscurtis]

Say what you want about the Duramax, good or bad, but I'd run toward one as opposed to Ford's last three diesel efforts.

 

[tuffs93]

A few years back a friend of mine sold me a almost new 08 duramax and his 40' toy trailer and sandrail ( he and his wife were transfered out of the country by the computer firm they worked for ) . I got a smoking deal on it and thought , why not ! My wife took me down and picked up the combo and headed home. Like you say, on flat ground it was pretty quick, untill we hit the mountians going home. Wow... . I thought , man , this trailer is heavy. Got it home and I thought , boy did I screw up. Couple of weeks later, Hooked my 04 duelly to it with the sandrail and 2 quads , fully loaded with water and food and headed to the dunes. My son was following me in the duramax. No problem, up hill,down hill,flat ground or the whole trip. Since then , my son has inherited the duramax. He loves it for running around Phoenix because its quick, but if he needs to pull a trailer, he uses one of the Dodges... .

 

[CBlack]

I can only imagine how much that truck was operating above its GCWR. No wonder the cooling system couldn't keep up with high ambient temperatures and steep grades.



Rusty

I'll have to look at his sticker and see when I'm over next. He says the 5er weighs in at around 15k.

Say what you want about the Duramax, good or bad, but I'd run toward one as opposed to Ford's last three diesel efforts.

No doubt! I'd take a Duramax but it'd be for performance purposes only.

A few years back a friend of mine sold me a almost new 08 duramax and his 40' toy trailer and sandrail ( he and his wife were transfered out of the country by the computer firm they worked for ) . I got a smoking deal on it and thought , why not ! My wife took me down and picked up the combo and headed home. Like you say, on flat ground it was pretty quick, untill we hit the mountians going home. Wow... . I thought , man , this trailer is heavy. Got it home and I thought , boy did I screw up. Couple of weeks later, Hooked my 04 duelly to it with the sandrail and 2 quads , fully loaded with water and food and headed to the dunes. My son was following me in the duramax. No problem, up hill,down hill,flat ground or the whole trip. Since then , my son has inherited the duramax. He loves it for running around Phoenix because its quick, but if he needs to pull a trailer, he uses one of the Dodges... .

I'm itching to hook my truck to something with him around and let him experience the Cummins first hand.

 

[Wingate]

I wonder if this is something inherent with the d-max engine... Our 4500 and 5500 dmax trucks always seemed to run at the edge of overheating, mainly on open highways in high ambient air temps.

I wold ahve to agree with others, with our current fleet of Ford 6. 7L trucks I can most assuredly state that we were in better shape with D-Max powered trucks. !

 

[MChrist]

I'm pretty sure it is in the 5s, but not positive about 5. 33. You are probably right, though. It makes me wonder that since the 5500 (and 4500 for that matter) are detuned versions of the pickup motor, if that makes them more "capable" work motors?? Maybe since the cab is different than the PU version, there is more surface area for the radiator?

Either way, I like mine...

 

[CBlack]

I can only imagine how much that truck was operating above its GCWR. No wonder the cooling system couldn't keep up with high ambient temperatures and steep grades.



Rusty

Can't remember exactly how to tell the GCWR.



The rear axle on his truck is rated to 8400#

The front axle to 4400#



GVWR is around 11500.

 

[Road Dog]

Can't remember exactly how to tell the GCWR.



The rear axle on his truck is rated to 8400#

The front axle to 4400#



GVWR is around 11500.

It's listed in the glossy brochure or trailer towing guide. It's just a guideline and maybe a declined warranty excuse but has no standing with highway inspectors. My '02 has a GAWR of 5,200F/7,500R, a GVWR of 11,000 and a GCWR of 15,000.



An oldie but a goodie: Dodge Towing Guide. Select by vehicle and then select the model year to get going.

 

[RustyJC]

It's listed in the glossy brochure or trailer towing guide. It's just a guideline and maybe a declined warranty excuse but has no standing with highway inspectors.

We're not discussing DOT regulations or "highway inspectors". We're discussing possible reasons for the Duramax's overheating problems. The GCWR "guideline" you summarily dismiss is used by the engineers who designed the truck to size the cooling capacity for the engine, transmission and rear axle.



Rusty

 

[rwitt]

I think the GCWR for that era of truck is 23,000lbs.

 

[rscurtis]

Keep in mind also that aluminum heads will transfer heat to the cooling system more easily than the CI head on the Cummins.

 

[Road Dog]

The GCWR "guideline" you summarily dismiss is used by the engineers who designed the truck to size the cooling capacity for the engine, transmission and rear axle.



Rusty

It's mostly picked by the marketing department so they can have bragging rights in their ads.



I suspect there's something actually wrong with the OP's inlaws transmission.



I have a friend with an '08 1T that he loads up and charges up and down the hills without a care in the world. He's driven manual Diesels for a long time and thought he's be manually shifting the transmission but it works just fine in automatic.

 

[RustyJC]

It's mostly picked by the marketing department so they can have bragging rights in their ads.

To some extent, but the engineers are left to make sure they will cool at the advertised GCWR and with some ridiculous frontal areas. I've seen them testing loaded trucks numerous times in the Davis Mountains of West Texas in mid-summer. This location is fairly handy to Firestone's high speed test track west of Fort Stockton and Goodyear's (IIRC) at San Angelo.



Rusty

 

[JimB1]

'06 Duramax owner admiring my '06 reg cab at the Credit Union, painfully described near $6K engine head gasket repair bill. 80K miles, he bought "nearly new" from Chevy dealer. Use was daily driver plus 1 month/yr travel trailer.



I un-artfully blurted, wow, that's nearly what your rigs worth. . , "yep" was 'bout all his response, never taking his eye off my rig.