Another JR

This was discussed in another thread to some extent. A person with apparent insider knowledge said it was an engine cooling related issue (not water cooling) and hinted it was emissions related, but they were apparently not at liberty to give details. My speculation that it is NO/NO2 related is just common sense based on emissions knowledge I have from my work. It is just speculation, though.

If you are referring to the “Ike Gauntlet” video, there was an engine thermal management feature (I’m guessing a nitrous oxides emissions related limit on exhaust gas temperature) that prevented downshifting late in the climb.

I meant was the 10 speed an option and you can also order the 6L90, or is the 10 speed the only transmission offered? Thanks.

As an option or are they only offered in 10 speed?

Aren’t you still in warranty?

I was simply pointing out to the OP that measuring the same water temperature when the thermostat is modulating flow does not tell you the airflow has not changed, contrary to their claim. I agree it doesn’t matter up to the point where the thermostat is full open.

Yes, the tire calculators say there is about 3/4 inch difference in diameter between the standard 18 and optional 20 inch tires. Your new tire size is maybe another 3/4 bigger. If you unlock your spare and crank it down just to the point where you can shift it around, you’ll be able to move it and judge how much additional room there is.

It would be close. I have the stock Michelin 275/70-18 tires and I’ve had my spare out to do some wiring. As I was restowing it, I remember I was able to shift it around about an inch, meaning there seemed to be room for about an inch more of tire diameter. I don’t remember what was limiting the movement.

Measuring water temperature when it’s operating in the thermostat control range does not tell you whether the airflow has changed.

That’s purely the dealer choosing not to keep their word to try and make a few thousand short term, not caring if they lose a customer for life. I ordered my truck in December 2020 and took delivery in April 2021 using the supplier discount, which was worth about $6k. The dealer said here’s the price with supplier discount based on the current pricing, and the price will only go up if GM’s price to us goes up. I agreed to that price, and it was on paper, but not on an actual purchase contract form. When the truck arrived, there had been no HD trucks on their lot for months. When I arrived to pick it up, the dealer said they’d had to lock their delivery room to keep people away from it. They told me they’d had three people try to make offers on it in the day and a half it was there. They proceeded to close the deal with me for the originally committed price despite the fact they could have sold it for 5-8k more. That’s what a reputable dealer does. They are interested in repeat business and referrals. This is the second vehicle I’ve bought from them, and I’ll go back if I ever need a GMC again. That was Brotherton GMC of Renton, WA. I have no affiliation with them.

Think about how the fluid from the reservoir enters the system as your pads wear and the pistons extend more. When the pedal is fully released, the brake circuits in the master cylinder are connected to the reservoir. That’s why you are able to use a power bleeder. Pull up a diagram of a master cylinder to visualize it. I’m speculating it may be a bubble in the master cylinder and pressing hard to stroke the master cylinder a greater distance shifts the bubble so it works it’s way back to the reservoir. Completely a guess though.

The feel of my brakes was pretty good from the start, but early on I did the procedure several have recommended on here to firm up the pedal feel, and it did improve somewhat (again mine already felt fine, whereas other have complained of a spongy feel. With the truck running and in PARK, push the brake pedal slowly and firmly as far as you can with large but not stupid force. Let it all the way up, then press it the same way again. I don’t know, but I suspect the reason this sometimes improves the feel is that it clears a bubble in the master cylinder left behind due to the factory filling a dry system and using a power bleeder rather than old fashioned pedal stroke bleeding.

Two comments: i wonder if there is an issue with your truck. Mine passes, accelerating from 55 to 70, on the highway very briskly with 2000 lbs of pop up camper in the bed. I’m very comfortable making passes on two lane highways. Your description of the power you get in that situation seems very different from what I experience. One of the times I most appreciate the heavier duty truck is when I have to brake really hard at highway speeds. I’ve had three serious panic stop situations so far in this truck, each time with the camper on, and it stops really fast under complete control.

Can you tell us the number of that bulletin?

By “aggressive” I think the OP means the selection of a gear that results in very high rpm as opposed to the characteristics of the actual shift from gear to gear. That’s what I was commenting on, at least. It actually shifts very smoothly. I just don’t like descending with the engine revving at over 5k. The highest rpms my truck has seen in its 6500 mile life were the one time I put it in tow haul on a moderately steep mile half mile hill near my house just to try it.

Page 234 of the 2021 Owners Manual. With foot off brake momentary push of start switch puts you in accessory mode. With foot off brake 5 second hold of start switch puts you in service mode.

My 2021 has the stake pockets painted. The under side of the bed is just primed.

This is my biggest complaint about this truck. I bought a 3500 so I didn’t have a choice and have the tow mirror blinders. I’ve been looking into whether they can be replaced with the standard 2500 power mirrors.

That post was longer than your new truck!

Hi. Yes I’m quite sure from the behavior, although I haven’t actually put eyes on the part number. My truck was built in early March 2021 and I took delivery in April. Driving unloaded it steadily works its way up to the 180-190F range and stabilizes, and will go up to 195F or 196 on long climbs.

Where are you finding information on exactly where to apply grease (fittings and other locations) and what type to use? Thanks

Just click on the heart in the lower right corner to like the post.

I agree with the OP that the downshifting in tow/haul mode when decelerating or descending is more aggressive than I would like for anything other than near maximum load.

I get the looks thing and parking lot ding protection, but what kinds of impacts is a bar like that actually intended for? I see the benefit of brush bars and big deer protection bars, but am honestly curious why this as far as functionality. It does look good, though. Thanks.

I’ve been regularly getting between 17.5 and 18.0 mpg (indicated overall trip average) on a long drive i repeatedly make on rolling, sea level terrain aiming to stay around 65-68 mph.