DuraMax diesel

BJnGrumpy

Active Expediter
My fiancee and I yesterday tried out a 2008 GMC Savanna 3500 extended CV,with a 6.6 Liter diesel 36,334 miles. I was wondering if that was a good engine and what type fuel mileage on the average we should be looking at? How much oil changes would be on an average? Not taking it to a truck lube though. Any issues as far as the engine goes? Thanks!
 
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skyraider

Veteran Expediter
US Navy
My fiancee and I yesterday tried out a 2008 GMC Savanna 3500 extended CV,with a 6.6 Liter diesel 36,334 miles. I was wondering if that was a good engine and what type fuel mileage on the average we should be looking at? How much oil changes would be on an average? Not taking it to a truck lube though. Any issues as far as the engine goes? Thanks!

I would go to a diesel truck forum where many people run these engines and u will get many reviews to make decisions on, plus call on a few engine rebuilders in ur area for their opinons IMHO:)
 

purgoose10

Veteran Expediter
My fiancee and I yesterday tried out a 2008 GMC Savanna 3500 extended CV,with a 6.6 Liter diesel 36,334 miles. I was wondering if that was a good engine and what type fuel mileage on the average we should be looking at? How much oil changes would be on an average? Not taking it to a truck lube though. Any issues as far as the engine goes? Thanks!

I have owned a couple of those and they are good engines if you treat them right.
Fuel mileage depends on the rear gear. If it's a 3.73 and you drive 62 -65 then you can expect at least 18-19 empty and about 17 loaded.
The only thing I have against it with Allison transmission is the weight. The Allison is heavy and so is the engine. Before you make a decision on purchasing I would weigh it and go from there.
Also I would not idle the engine at all. Get other means for heat and A/C. The Duramax will load up on you and that drops fuel mileage.
Also when you start the engine even if the engine is warm wait for the engine start light to go off. If you jump the gun when starting and get into a habit of it, will shorten the life of glow plugs.
I have a friend who runs double with his wife and has over 750,000 on his and it's still running strong.
 

purgoose10

Veteran Expediter
If I'm not mistaken, they're not using the Allison in the vans.

I went back to check my paperwork. The Allison became available in 2006 in Extended 3500 only. L80 was in the 2500.
The 6.6 engine was and still is rated at 250 but can be re-programed. You will get better fuel mileage if up graded to a 325 -350 hp if you keep your foot out of it.
.
 
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scottm4211

Veteran Expediter
Owner/Operator
I went back to check my paperwork. The Allison became available in 2006 in Extended 3500 only. L80 was in the 2500.
The 6.6 engine was and still is rated at 250 but can be re-programed. You will get better fuel mileage if up graded to a 325 -350 hp if you keep your foot out of it.
.

That's the first I've heard of the Allison actually being used in the van. I'd still like to see better fuel economy out of the Duramax but I guess 6.6 liters will do that to you.
 

Brisco

Expert Expediter
I went back to check my paperwork. The Allison became available in 2006 in Extended 3500 only.

The Allison has never been available in a Chevrolet Express Van or Chevy Express Cut-Away, any year, any time.

Something to do with the size of the Allison itself. It will not fit in between the frame rails,(too narrow) would sit way too low in the frame itself if they did happen to get it in, and the whole engine house(or bunk cover) in the interior would have to be redesigned.

Better double check your paperwork........;)
 

tumbleweeds

Expert Expediter
Owner/Operator
I was at the dealers last week. He said the cutaway was available in the gas 6.0 or the Duramax with the Allison. He said the Duramax had to be tuned down to allow for the Allison. The biggest problem I found was there was almost no leg or foot room on the passenger side. We chose not to get one because as a team, it was uncomfortable in the shotgun seat. He was driving a 2010 CargoMax with the Duramax and the Allison. Just a FYI.
 

scottm4211

Veteran Expediter
Owner/Operator
The Duramax is already turned down to 250 hp with the regular trans. Wouldn't the Allison allow for greater hp/torque capacity?
 

Moot

Veteran Expediter
Owner/Operator
Hey Weed, what was that dealer selling, cars or something else.

The DuraMax will add almost 600 pounds to the curb weight. Something to consider, especially running team.
 

Jack_Berry

Moderator Emeritus
the only folks who have the van diesel down right is mercedes and i don't own one but can say that. right size and weight oir the package. unfortunately the gummint is killing the mpg with the continuing cali exhaust laws. typical of american engine building is the larger is better thinking.

reference this thread......
.
http://www.expeditersonline.com/forum/truck-talk/46499-american-diesel-vanners.html
 

purgoose10

Veteran Expediter
The Allison has never been available in a Chevrolet Express Van or Chevy Express Cut-Away, any year, any time.

Something to do with the size of the Allison itself. It will not fit in between the frame rails,(too narrow) would sit way too low in the frame itself if they did happen to get it in, and the whole engine house(or bunk cover) in the interior would have to be redesigned.

Better double check your paperwork........;)

Better check again. 2011 you can get both the 6 spd and the allison.
The allison will cut the flooring space on the pass/side and weigh's more.
 
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Brisco

Expert Expediter
I was at the dealers last week. He said the cutaway was available in the gas 6.0 or the Duramax with the Allison. He said the Duramax had to be tuned down to allow for the Allison.

He was driving a 2010 CargoMax with the Duramax and the Allison. Just a FYI.

Again.....there is no such animal, a GM Express 3500 - either CV or Cut-Away, or even an Express 4500 Cut-Away, that has the Duramax/Allison combination in it.

I thought maybe GM had finally redesigned that frame on those
trucks to accept the Allison tranny, so I spent a good hour researching it myself.

Went to Tools GM Fleet - Tool Information | GM Fleet

Worked my way to the coded Mechanical options list:

Model Information - Online Ordering Guide

And all the way down at the bottom, I found the only Transmission available for these trucks with the Duramax:

Transmission - Specifications

The only transmission available for the 3500/4500 Express series vans is the "MYD - AUTOMATIC 6-SPEED HYDRA-MATIC 6L90".

Then, to satisfy my curiosity and findings, I called a Salesman I've known for years over at "The Thompson Group", Chevrolets largest FLEET Sales dealership in the country, just to clarify my findings.

Classic Chevrolet Fleet Sales

He basically laughed at what I said was going on here. Chevrolet has never offered the Allison Transmission in a 2500-3500-4500 Express Series Vehicle with a Duramax. And until GM beefs up that frame, and raises that suspension to pickup truck heights, never will, Period. The size of the Allison tranny is just too large for that set-up.

So, not to bust a bubble here, but FYI, whoever it was who said they were driving a 2010 "CargoMax" with a Duramax/Allison combo had their head up their................:rolleyes:
 

Brisco

Expert Expediter

scottm4211

Veteran Expediter
Owner/Operator
These companies rarely seem to make major changes in body or frame stampings mid cycle. And if it were offered it'd be nice if they would advertise it in some way.
 

Brisco

Expert Expediter
Just having a little fun here....

Engine/Transmission/Axle Reference Guides:

2010 Express Cargo

Model Information - Online Ordering Guide

2010 Express Cutaway

Model Information - Online Ordering Guide

2011 Express Cargo

Model Information - Online Ordering Guide

2011 Express Cutaway

Model Information - Online Ordering Guide

2012 Express Cargo

Model Information - Online Ordering Guide

2012 Express Cutaway

Model Information - Online Ordering Guide

Can't seem to find RPO Code MW7 - ALLISON TRANSMISSION anywhere. :confused:

Why??

Cause they don't offer it in these vehicles!!

OK, I'll shut up now. Point Proven..........:p.............
 

Brisco

Expert Expediter
The 6.6 engine was and still is rated at 250 but can be re-programed. You will get better fuel mileage if up graded to a 325 -350 hp if you keep your foot out of it.

For the Express Series vans, the Duramax was derated down to 250 HP because the MYD 6 Speed transmission cannot handle the 350 HP the Duramax is capable of producing.

If you do "re-program" that Duramax back up to it's proven HP, you'll be at risk of blowing that MYD Transmission in your van or box truck. That's a repair bill I'd hate to have. Know what I mean.
 
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