C/K Man

With the expansions to Flint and Oshawa coming on line GM has really increased HD truck capacity. THis will allow GM to more effectively challenge Ford on the commercial side, a market where GM has struggled in the last few years. The company I work for buys a lot of GM HD's, and there were long periods where GM was only making loaded crew cab HD's and we couldn't get the regular cab cab and chassis models we buy. I wonder if GM is giving any thought to moving medium duty commercial truck production back to Flint. Silverado medium duty and G-cutaway trucks are coming from Navistar in Springfield OH and the LCF's come from Shyft Group in Charlotte MI..

The RCSB 1500 V-8 model ran in to trouble meeting the new EPA/CARB 'footprint' (based on vehicle size) regulations. I am told the F-150 RCSB with the 5.0L really isn't available anymore either.

Rockauto.com shows Platinum Driveline CC1201 fits an 8.1L C-7500 TopKick. Part is out of stock but may not be discontinued. TruckID also has a listing, also out of stock: https://www.truckid.com/2003-gmc-topkick-transmission-parts/rhinopac-clutch-cable-4035198314.html

Good to know. My company had a heavy duty GMC dump truck back in the day, it had 4 RPO stickers on it.

I wonder if L8S be based on the upcoming Gen. VI LS/LT design.

A lot of engines like the L96 and L8T actually do have 'EGR', they just do nor have an EGR valve. Many engines use VVT for EGR, they open the intake valve before the piston hits TDC on the exhaust stroke. This blows some exhaust up unto the intake port, which is drawn back into the cylinder during the intake stroke. This VVT EGR effect also contributes to residue in the intake ports on DI engines as there is no fuel spray to wash it off. It also the reason you usually only see the intake deposits in the ports of DI engines right around and valve, the exhaust doesn't get much of a chance to get and further up the port. There is also a condensing effect as the exhaust is actually hotter than the valve so deposits tend to stick to the port side of the intake valve. High quality gasoline really helps to keep the intake port and valve clean, even on DI engines. Speaking of Ford's 'Godzilla' 7.3L, I suspect it will gain DI sooner rather than later. I am also hearing Ford finally figured out the cam/lifter issues with that engine. Seems the variable displacement oil pump was allowing oil pressure to get too low during idle. Ford is fixing it with a re-flash. So the next gen. L8T will become the L8S. Very interesting, that would indicate we will likely see some major changes. I'd like to see them stroke it a bit to get the displacement up, but I think that would require going to a high deck block which I doubt will happen. I wonder if we will see a renewed interest in E85. Since the L8T came out the E85 option has only been sporadically available on certain configurations and trims. No doubt there will be some changes to meet new emission regulations, but I think GM will do their best to keep the engine competitive.

Chevy currently offers a LCF 7500 with a 260 H.P./660 ft. lbs. 6.7L Cummins in it, GVW around 32,000#'s. No powerhouse, but pretty typical for a class 6/7 city delivery truck. A hypothetical 400 H.P./800 ft. lbs. 8.3L would do just fine

Looks like the lining fell off when the metal part of the shoe started to rust.

And that raises more questions. An 8.3L diesel is awfully big for a pickup truck, and it's even large for a medium duty. Either the upcoming more stringent diesel emissions regulations are going to require a displacement increase to maintain the same H.P. and torque the current 6.6L Duramax makes and/or Chevy is planning larger commercial trucks. Maybe a Silverado 7500?

FWIW: I am hearing the 1500's will introduce 2026 as 2027 models, the HD's a year later. The actual platform may not be 100% new, it will be known as T1-2 which suggests it's related to the current T1XX truck. Everything you see from the exterior and interior will likely be new however. The trucks will feature the Gen. VI gasoline V-8 which is rumored to still be a pushrod LS derivative. What diesel T1-2 gets is a bit murky right now however. You may have heard of a rumored 8.3L Duramax being developed, some say it will be in the next generation HD's but some say it's a commercial medium duty truck engine. Maybe it's both? A little speculation on my part, Ford recently announced their Super Duty trucks will eventually be available in hybrid and BEV configurations and I would be willing to wager GM has similar plans for their HD trucks as well. I wonder if GM will need to switch to aluminum bodies and maybe a slightly smaller size to reduce weight for upcoming emissions/fuel economy/GHG regulations?

The beauty of torsion bars is as they develop a little 'twist' over the years, they are easily adjustable.

newdude is right, the cabin air filter was eliminated in 2003. The space for it is still there, but the HVAC box mold was changed on some trucks and there is no retrofit kit available (have to make your own like the guy in the video did). On others the access panel is there, GM just didn't put a filter in it. It all depends on which vendor the box came from, Delphi or Visteon. There is an AC Delco retrofit kit for adding a cabin air filter to the 2007 and newer GMT 900 trucks, but it does not work on the older trucks.

Also check the fuel pump connector for burned or corroded terminals.

Do what he said. The piston could be sticking in the caliper, otherwise it may be an ABS problem.

you might try these guys: https://oemradios.com/

Module 19245410 is available on line from several vendors. NAPA has the TPS. Can't find the pedal assembly, might have to try a wrecking yard.

Have been using the Primacy XC LT235/80R-17's at work on 2011-2019 cab and chassis dually's, all gas powered and loaded pretty heavy. No issues.

As far as I know that system was exclusive to U-Haul and was not a regular GM option. You might try contacting U-Haul, they do supply some of the unique parts used on their trucks and trailers. The system was similar to what was used on some GM and Workhorse motorhome chassis but I have no idea what parts interchange. The other way to go would be to find a Topkick or Kodiak with a mechanical parking brake in a wrecking yard and switch over. https://trucksales.uhaul.com/Parts

I don't think so, never seen one on a box van.

Particulate filters on gasoline engines will be a non-issue. Gasoline engines produce far less particulates than diesels, so much so that regeneration on a gasoline engine PM filter should not be perceptible. Of course adsorber catalysts requiring DEF will not be necessary. PM filters have been on gasoline engines have been used in Europe for some time.

So, it looks like the 1500's will be updated for 2025, any word on the HD's? Assuming the HD's are usually a year or two behind the 1500's I figure any new HD would be expected around late '26, maybe as a 2027MY. I know a new generation of LS/LT gas engines are on the way, and there is a new Duramax coming, but I have not heard of anything else. Also, the Silverado Medium duty trucks may get some changes too.

That's good information, but there is another factor. Late model engine with variable valve timing open the intake valve before the piston reaches TDC on the exhaust stroke. This is done to recirculate exhaust gases (EGR) back in the combustion chamber without using an EGR valve like older engines did. Those exhaust gases are blown up into the intake port momentarily before the piston goes past TDC and starts down on the intake stroke, which draws the exhaust gases back into the cylinder along with the incoming intake charge. The exhaust gases are hotter than the back side of the intake valve and the surrounding intake port, so they tend to condense on those surfaces eventually leading to deposits if excessive. That is why when you see intake valve/port deposits on an engine the deposits are seldom more than an inch or so above the valve, the exhaust gases don't have a chance to migrate very far up the intake port before being drawn back into the engine. While it is true crankcase ventilation (and leaky intake valve guides) can contribute to intake valve/port deposits , most all of what you see these days is from the EGR effect of variable valve timing. Of course, port type fuel injection (and quality gasoline) did a great job of keeping the intake clean, and with GDI alone we don't have that 'luxury' anymore. A 'catch can' may reduce intake deposits slightly, but the best way to keep the deposits to a minimum in a GDI engine is with good quality gasoline, the proper synthetic motor oil, and good maintenance. FWIW I have a friend with a GDI 3.6 2013 Impala with over 200,000 miles on it. No issues with excessive deposits. I wonder about using E85 in GDI engines. E85 capability is still an option on some Silverado/Sierra HD's with the L8T. I have seen engines run on E85 for many miles with almost no carbon deposits in the combustion chambers, if you are not making the deposits in the cylinder I don't see how you would have any in the intake port.

Does this help?: Document ID_ 724407.html

Bulletin 19-NA-255 has been updated again, same issue with the wax coating not adhearing to the frame but now includes some 2023 models. With all the problems GM has been having you wonder why they have not gone back to painting the frames. There were quite a few rumors GM was going to do just that but it has not happened yet.

A semi floating rear axle has axle shafts that support the weight of the truck. You can tell a semi-floating axle by the absense of a protruding wheel hub. The axle shafts in a floating axle do not support the weight of the truck, they only turn the wheels. The hub has bearings that ride on the axle housing which supports the weight of the truck. Floating axles have protruding hubs that have bolts attaching the shaft flange to the hub. There are 3 different axles that have 14 bolt covers. The 9.5" is a semi-float design with a round cover, the 10.5" which is a full float design and has a cover shaped more like a stop sign, and an 11.5" full float that is very large and is only used on certain 2500's and 3500's. Some axles have fill plugs, some do not, so most aftermarket covers do have plugs.