17 Express 2.8 Diesel

You have a 3500 and I have a 2500, so I would think that at least the springs would be different. What's the website address? I was thinking defective shocks too.... since it only has 6500 miles.

StanVan

https://www.gmpartsdirect.com/

I use this site for reference for questions like this. I have bought from them, but I use Rock Auto more. And I had to guess at your exact model, but I have an LT, so I compared yours as an LT as well. It didn't ask about the wheelbase length. I have the long one.

17 Express 2.8 Diesel

Thanks for the website link. I probably have the base model ( cargo van) and it shows different springs for the 2500 and 3500, but the same shocks. I'll probably have to change shocks, since the dealer thinks they are ok and functioning normally. That's a disappointment, but besides the transmission shift points being too high, I like the vehicle. I figure there is about a 10% loss in fuel economy at most highways speeds because the transmission won't shift into high gear until 67 mph. We get about 27 mpg at 60 mph, but 30 mpg at 70 mph.....rpms drop from about 2200 to 1500 when the trans finally shifts to 8th gear. 1500 rpm provides plenty of power at 70mph..... about double what it takes to keep the 7500 lb vehicle moving on level ground

greenfire

Well it is great to hear from someone with the small Duramax! I wonder if the van is off balance because of a lighter engine in the front? The vans were designed for heavy V8 engines, so I wonder is a small 4 cylinder is throwing it off balance. Otherwise this is an interesting development. I have never had a G van with that issue. Keep us up to date and hopefully some other 17 and 18 owners will chime in.

StanVan

Makes sense to me.

17 Express 2.8 Diesel

I looked around online, however, and the numbers were about 520 lbs for the 2.8 Duramax and around 505 for a 6.0 gas v-8. Never can be sure of those numbers, but I think I checked van curb weights too at one time on the 2.8 versus the v-8 and they were about the same. Diesel engines are very very heavy. We'll see if anyone else chimes in that is running the 2.8 with alot of weight.

I also just had a chance to do some longer highway driving with it loaded and managed 33.3 MPG over 60 miles on Interstate 80 just outside Chicago. I was trailing behind a semi most of the way so I am sure that helped. Ended up at 32.2 mpg once I got off the highway onto city streets, after dealing with the slow downs and running in 7th gear for the last 20 miles or so.The semi was doing just a little over 65 so I was able to set the cruise control at 65 to keep the tranny in 8th and then add a little extra speed when I started falling behind. 33.3 is probably the best anyone will be able to get with a stock loaded van. I hope to do a little aero work and maybe get the trans reprogrammed to hold 8th gear at lowers speeds to be able to improve on the mileage.

StanVan

I'd like to have found one website that had info on both, but we can't always get what we want. I found the 2.8 at 520, but the 6.0 was 580. Both sport a cast iron block, with aluminum heads. I find it hard to believe that twice the cylinders is only a 60 pound difference. I did find one site that said the 2.8 weighs more than a 3.6 V6, so maybe.

17 Express 2.8 Diesel

I was a surprised too when I first looked them up. I imagine the block and heads are quite stout due to the really high compression, the crank and rods are forged and it has 4 valves per cylinder, so I guess that all adds up to one very heavy engine.

Teammuir1

ALL this speculating ..... ( GO CHANGE SHOCKS ) and come back and give us a report... lol......
I too have new shocks and now that they have been on and I have broke them in
I am very happy with the results... I bought the same kind STAN VAN has.....

17 Express 2.8 Diesel

Teammuir1 how much weight are you carrying regularly? Or is the van only occasionally heavily loaded. I sprung for Bilsteins last time on my old E250 and the improvement was interesting..... better absorbion of bumps (not as stiff) and much better control. However, my suspension shop did say that the one of the factory front shocks was defective. It almost caused an accident on the Pennsylvania turnpike during a rainstorm while towing a pop up....started going sideways into the next lane wile braking. Heavy duty shocks may be too hard for lightly loaded vans, while just right for heavy loads. Some are supposed to adjust, however.
I 'll do the shocks soon.... budget is a bit tight at the moment.