Grey3liter4x4

Just wanted to post some information in the event someone with a vehicle similar to mine starts to get engine check lights and a loss of intercooler coolant. I've had my truck for almost 2 years. Had the leaking rear slider fixed, a seat belt recall, and the occasional random cel that would pop up and then go away on its own. I have a scanner and some of the codes were very random but nothing that effected how the truck drove or required a visit to the dealer, until.....6 months ago I get a persistent P026A code. Code is basically the incoming air charge from the turbo is outside of acceptable parameters. 5 trips to the dealer with a weekly loss of coolant from the intercooler expansion tank the problem was finally figured out. GM has a service recommendation for the techs to check a possible kinked lower hose on the drivers side that would restrict coolant flow but that was not the problem. Basically what was happening was the coolant for the intercooler was not flowing into the intercooler from the engine side. Coolant was getting overheated and over pressurized in the fill tank causing it to blow past the cap, supply hose clamps, and through the overflow tube. All at different times and only after the truck had been driven hard, highway speeds over 30 mins long, hot days, long hills, etc. Pressure testing would not duplicate the leak, fill tank was changed, replaced hose clamps, and on and on. The tech finally figured out that one of the hoses from the intercooler on the passenger side of the engine had a union that was installed backwards at the factory. The incorrect installation was creating a kink in the hose. As the coolant expanded the kink would get worse essentially closing off the normal flow of intercooler coolant. Heated coolant coming off the motor had no where to go but out of the tank. The kicker is that there is a trim piece that completely covers the hose where the fitting is located. Unless the tech knows to remove the cover and inspect the hose there is no way to tell there is a problem. The fitting was removed and flipped around to remove the kink and so far so good. In all the months of trying to figure out the problem I could not find any reference to a P026A code and a 3.0 duramax. So hopefully if this is someone else's problem have them check that hose fitting if they can't figure out.

I have a 2020 and from day one I thought my spare tire was loose. Uneven terrain, taking a speed bump at an angle and especially backing out of an uneven driveway the clunking is worse and loud. From digging around here and on other sites I found my issue was the leaf springs are slapping against one another in the spring pack, especially when they are being twisted. Dealers have packed the springs with grease which will work for awhile and once it gets dry the sound comes back. A member here had a how to to add heavy duty rubber as isolators between the springs. I added the extra rubber between leafs and it did help muffle the sound but really never went away. You get used to it once you realize there's not much you can do and it isn't doing anything bad. Loading the truck with weight will also make the sound go away. I usually do 200 lbs in the winter for traction and the extra weight doesn't allow the leafs to slap against one anther when they are being twisted. I also just installed a set of Airlift airbags and that has also really tightened up my rear end even when theres no load. Really improved the ride and quieted up the clunking to the point its basically gone. Still need to drive the truck more but the few test drives I did are like night and day.

I agree if sealant is of sufficient quality and is applied evenly and properly across the top of the frame there should be no way for the window to leak even with continued cracking of the frame. My bet is sloppy work or the sealant not being evenly applied across the top of frame. I also I just went out and checked my window to not jinx myself. 3 months after the repair date my window is still good, no leaks. It has also been raining at least 2-3 times a week and the truck has been through almost daily freeze thaw cycles. I guess I was lucky that the dealer did a good job so far. From this thread I tried to explain to the service manager most likely the leaks were from small cracks in the frame and to try to apply the sealant evenly across the top of the entire frame and on the frame itself as people were getting continued problems after initial repairs were done. Once the spoiler is put back on it is almost impossible to tell how good of a job the tech did. I could see through the gap though it appeared they applied the sealant over the top of the entire frame. I really love my truck and aside from this problem I feel like the purchase was a good one. Baring any further problems I'm hoping to keep the truck for awhile. With all that being said as I posted before there are sealant products out there that are relatively cheap and extremely strong and completely waterproof. If my window leaks again I'm going to hire an auto window guy or tackle the problem myself and apply this https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Marine-Adhesive-Sealant-5200/?N=5002385+3293241623&rt=rud it may be overkill but once applied it will be good for the life of the vehicle. This is rated for below waterline applications on boats.

I had the dealer apply sealant per the TSB to my 2020 leaker. So far so good but from the sound of it it will most likely leak again as a crack develops in the window frame. If it leaks again I'm going to apply https://www.grainger.com/product/3M-Black-Marine-Adhesive-Sealant-4YDL2?opr=APPD&analytics=altItems_2JBH1. I used to do boat repair and 3M 5200 is about as bullet proof as you can get for an adhesive sealant. If applied properly it will be almost impossible for the window to leak. We used to attach boat cabs to hulls with this stuff. The only problem is it's basically permanent.

Fabtech 3" coil over lift with 34" tires. Wrapped all the LT chrome with matte black. Removed all the badges.

Ahh bummer, sorry ? At least they gave me an Equinox to drive.

Discovered why there are no diff drop kits for a 2020. Took the time to crawl under the truck and there is no way 4 small pucks of any design are going to lower the front diff. The front differential is bolted into several frame pieces vertically and horizontally. There is no way that I can see you'd be able to drop the front diff without some sort of subframe or without heavy modification. Beware of any Ebay kit that says it fits with pucks/spacers and longer bolts.

Picked up my truck after the dealer kept it over the weekend to let the adhesive dry. My leak was only from the slider rail on the passenger side. They applied a sealant to the outside of the window frame as part of the TSB from GM. The vehicle had a very noticeable chemical smell in the cab from the sealant. You can also see where they applied the sealant at the top of slider from the outside. A bit sloppy in places but as long as you don't actually look carefully its not noticeable. Also no sign of them removing the headliner or the spoiler. Was worried it would be damaged or dirty. So far it's dry after melting snow and rain on the roof the past 3 days. Keeping my fingers crossed.

I'm lucky, If you can call it that, I live in a dry place. Such a shame that these vehicles are leaking. Seems like such an avoidable problem. You can watch the robots sealing seams and installing glass at the factory online. Somehow there's a glitch in the assembly line that GM isn't addressing. My $250 GMC that was my first vehicle had holes in the floor but was still water tight, unless you ran over a puddle.

Just got home from a day in the snow in the mountains. In AWD there is a very slight vibration at 55 that didn't seem to get worse at higher speeds. In 4 hi though nothing, smooth and easy. Not sure why that is but it is. Would still like to drop the diff to improve the axle angle. Was thinking of the longer GM front axles in the factory TB lift but unless they're designed for greater angles it doesn't address the original problem. Still haven't found an actual diff drop kit for the 2019/2020 trucks other than Ebay.

I suspect I have too much front driveline angle after a 3" Fabtech coilover lift. Getting vibration at speed in AWD. Has anyone found a good kit to drop the diff? You can find the kits on Ebay but sometimes it's hit and miss with Ebay. Looks like there are plenty of options up to 2018. I'm having a hard time finding out if there were any changes in the suspension from 2018 to the new body styles of 2019. Thanks

I'm lucky, If you can call it that, I live in a dry place. Such a shame that these vehicles are leaking. Seems like such an avoidable problem. You can watch the robots sealing seams and installing glass at the factory online. Somehow there's a glitch in the assembly line that GM isn't addressing. My $250 GMC that was my first vehicle had holes in the floor but was still water tight, unless you ran over a puddle.

Leak is only at the window frame. Spoiler has to come off to get to the window for sealant application. I'll ask though on what they did exactly, hopefully tomorrow and let you know.

I have the Fabtech 3" with the loaded coils and shock combo. I'm also getting a very slight vibration in AWD around 55-60. Figured it was the 34" tires. Also nothing in 2WD at any speed. It just started snowing and the roads are getting icy/snowy. Will post back once I get my truck back from the dealer for the window leak. Not sure if it does the same thing in 4 high at those speeds in the snow yet but I'll let you know. And yes I don't like to drive at those speeds in 4 high in the snow but straight downhill sections of road its hard to avoid it. Wonder if the longer GM front axles on the factory 2" lift would fix the problem?

Took my 2020 to the dealer on Friday for the leak on the passenger side. Its supposedly their first. No cracks were found on the slider frame. Having the headliner, spoiler removed to apply sealant. Will see if it works.

Hair Dryer works great. Don't need to get the decals very hot especially on a new truck. Amazon sells 3M and off brands of adhesive removal wheels for drills, basically a big pencil eraser. They are hard to first use if its your first time as it seems so wrong to aggressively apply a gummy wheel to your brand new vehicle but they don't damage the clear coat and make the removal easy and fast. Once the majority of the adhesive is erased I'll use goo gone or alcohol to remove the last small areas of residue. If you only use goo gone without the eraser wheel make sure the rag is very clean. Hard rubbing with a contaminated rag will scratch the clear coat. I did a complete decal and de-badge of my truck and it took right about an hour. There were duramax, Z71, and LT badges all over the vehicle.

Found this online on a general search. Most of you may already know about the TSB link but here it is https://static.oemdtc.com/TSB/MC-10156903-9999.pdf. Going to print this out and bring it in with me to the dealer.

Yes I would definitely! It doesn't take much if it's leaking from day one. I never took my truck off road and the weather has been mild, no freezing thawing cycles since picking up the truck and no popping sound as some have reported. The dealer usually washes the truck prior to the sale. There will be dried water spots on the inside of the window usually on the passenger or driver side of the window or actual water if it's been raining.

You can add me to the list of leakers. I suspect mine has been leaking from day one. 20' LT crew cab with the slider built in Mexico. I believe it has a late 19' build date. Mine is leaking from the bottom of the top track on the passenger side, no wet headliner. For now I have a small towel as well to catch the water. I'm lucky I live in a dry climate but I'm worried about this winter and the snow.

Thanks for the replies! Yes that is pretty much what I do, 4 HI and I've already changed out the tires to snow flake rated tires. The situation where I've used engine braking to assist with stops are usually at slow speeds and slight declines requiring a stop. It's not so much my driving its people around me. There are inexperienced and dangerous drivers that either brake too hard or are driving like idiots (too fast for the conditions, following too close to others, and hard braking in front of you). Its just the reality of the town I live in. There is a ski resort near the town and when the snow is good people are crazy to get to the mountain. There are also icy downhill sections of heavily traveled roadway where engine braking really helps in slowing you down without having to risk sliding from taping your brakes.

I do a fair amount of driving in snow and ice. This is my first GM in a long while and I was curious if any of you have any tips on using the manual shift feature on the 10 speed transmission while driving on icy/snowy roads. My previous vehicle was a Tundra and the manual shift feature worked really well on icy roads especially to assist with slowing the vehicle down. Prior to the full onset of winter I'll be adding weight to the bed to help with traction as I've done with my previous vehicles. I'm aso going to and test the feature in an icy parking lot at some point but wanted to see what some of you do when your faced with frozen roads. Thanks

Brilliant! My wife would love it if I planted some kale.

If the dealer can't fix mine or won't maybe I'll hang a small potted fern below the drip. At least the water won't go to waste.

Finished most of the alterations to the truck that I wanted to do. Truck is a 2020 LT Duramax. Wrapped the bumpers, mirror caps, and front end in matte black. AVS in channel ventvisors (not a good choice, anti pinch is driving me nuts when windows don't stay up), tint, de-badged, Fabtech 3" coil overs with UCA's, Vision wheels 20x9" zero offset, Falken Wildpeak AT3W 295/60/20's (tire only rubs on passenger side at full lock, weird?). No spacers on the wheels. Pretty happy how it looks and rides. Tires are 10 ply so they are heavy. I was worried the truck would struggle with the larger tires and added weight but can hardly tell at all. The diesel motor with all that low end torque really makes up for any extra weight of the tires. Lost a bit on mpg but it's not a problem. Also I can add myself the the passenger side leaking rear window club. Found drips today after washing the truck ?. Oh well hopefully GM comes up with a good repair. I'm lucky I live in a dry climate, going to wait awhile to see what GM comes up with for a reliable fix. It really is something to pay full price to have a window leak as part of the deal.

I hear you, highway driving is really like a game. To watch the mileage average climb above 30 mpg on most long distance drives is something. I've never liked are been interested in GM products. After doing as much research and reading on the new 3 liter Duramax as I could I'm more than pleased on my choice! Yes the interior isn't super slick but that has never been a buying point for me anyway. The best mileage I ever got on my Tundra was 18 mpg and I don't miss it one bit or the small gas tank.