K2xxSteve

Amen, brother! Found the ONE thing that matters in life. PTL! It's really a shame on my ill-fated Burban, because we just bought a near the beach property in Delaware hardly a month after I traded it. Didn't think it would happen, but finally found a place we loved and went for it. It really would have come in handy with its superb towing and hauling abilities getting stuff from MD to DE, but the X7 is a fantastic tow vehicle also. Lots of things I've been hauling wouldn't have fit in the Suburban anyways, so I've been renting U-Haul 5x8 trailers for next to nothing. The B58 will tow all day long in 7th gear, and you never know anything is there. I'd say it's as good or better a tow vehicle than the Burban, and I had max tow and 3.42 gearing. I considered a closeout Ford Expedition (the now previous model). Massive discounts $10-12k off MSRP without even negotiating. Regular Tahoe sized one and not the Max would have been fine for us now. Liked it but didn't love it, and new car prices have gotten ridiculous. The CPO X7 was the same price and not really all that much smaller inside, and drove a ton better obviously, so went in that direction and haven't looked back. I know BMW's well. This is our fourth. We had an E70 for six years also, a 2012 X5 35d which was fantastic. We traded that for the Suburban. Recently got my wife a CPO 2022 G05 X5 with a mere 4k miles on it, now my G07 X7, and still have the 2011 E93 335i that I bought new. There's a really good indy BMW shop within walking distance from me also, so it makes sense. Funny thing is the X7 has an air suspension system that's known for FIVE-figure repair bills, so this time I went for the platinum plan extended warranty. I hope I don't need it. Just to stay on topic, there's a lot more discussion about aftermarket suspension options including various Magneride deletes and other things you can do over at tahoeyukon forum dot com. I researched until I couldn't see straight, and came to the conclusion to just suck it up and do the full OEM Magneride replacement. Ride quality aspects are so nuanced and subjective that unless you can personally ride in a vehicle with the suspension setup you're considering, who the heck knows if you'll be satisfied or not? Very easy to blow tons of money on something you won't be satisfied with, and difficult to get straight answers even from the aftermarket companies. Just stick with OEM. I'd have done it, but then the stupid lifter issue on top of that and the master tech thinking things were too far gone and to just replace rather than repair, good grief. Still bitter, but enjoying having a daily BMW again, and love the deal I got on it.

Saw your message. Ended up trading the truck. Glad I dragged my feet for a year on the Magneride replacement, because by the time I was finally ready to suck it up and spend $5-6k on full Magneride replacement and airbags too late last year, the engine was letting go. Frozen/stuck lifter grinding out the cam and "tick of death". 97k miles. Master tech with 30+ years experience at my local indy shop took a look at it, and recommended I either trade since it was still under 100k miles and no check engine light yet, or get a replacement engine. Couldn't believe it. $10-15k in repairs needed on a truck with still under 100k miles? I was not expecting perfection from GM by any means, but holy moly. Anyways, got $23k in trade for it, and picked up an off-lease low mileage CPO 2022 BMW X7 with tow package.

So the new thermostat came in on Thursday and took it to a good local shop on Monday. Just short trips on Monday, but finally had a nice 40 minute drive today and it seems solid. Mostly stays dead-on at 207F actual in light driving and 50 degree outside temps. Forgot to take a photo of the one that came in, but it was a genuine GM part complete with GM and part number stamping, taken from a full water pump assembly as described in the eBay listing. What a freaking hassle, but glad it's finally fixed! The guy on eBay still has plenty of these if anybody needs them. $199 is a ripoff (I paid $149) but it is what it is when you can't get them elsewhere: https://www.ebay.com/itm/115727184809 You can get the full water pump assembly from which he's taking those from for only $50 more from Rock Auto, and elsewhere. Just remove the thermostat if that's all you need, and sell the water pump or keep it as a spare. https://www.rockauto.com/en/moreinfo.php?pk=10622996&cc=3438969&pt=10178&jsn=492 40 minute drive log attached. It's working as it should so not going to do another cold start test and waste more gas.

Thank you, Grumpy Bear! Have seen your posts in a bunch of the other thermostat related threads here, which were very helpful! Good lead. So I have two of the 207 F OEM on the way (15-11125), but this might be helpful to someone else reading. I wasn't sure what the OEM prices were, but figured what I was paying on eBay was about on target. Just curious, but which Cadillacs do the -13 PN / 194 F rated go into?

This is off that listing. Has GM and correct part number stamped into the housing. I bought another one that was listed as a Genuine GM part from another seller just in case. If the first one works out and I don't end up needing the backup, will either return it or re-sell it here in the FS forum. What a CF!!!!

Next problem has been finding where I can get a genuine GM thermostat assembly from. It appears this is a very common issue, which combined with the GM strike, has lead to widespread parts unavailability. A couple days getting run around and ripped off by the dealership, and then a couple days genuinely trying to be helpful run around by a local shop asking legit questions making sure I wasn't fixing the wrong problem before I dump more money into it, and the two that had been found are gone. The local shop (good guys) had found an OEM part last Thursday but now gone, and a part my buddy had found at a parts store down in GA (I'm in MD) was also gone. F me! Sooo.... off to eBay I go. I'm not sure where and if this is the same seller or not, but I'm 99% sure I had seen a post somewhere about these being legit. Someone here had ordered one somewhere. Per the description, they're new OEM thermostats off of the water pump assemblies. After reading a lot of bad reports here about the MOTORAD's being unreliable and/or not maintaining the correct temperatures, I feel safer buying this than the MOTORAD, so will see how it goes and report back! Listing link is here. There were 6 left, now 5 after I purchased. https://www.ebay.com/itm/115727184809

Additional troubleshooting steps over the weekend, and trying to 100% confirm the issue and that it wasn't something else before I dump more money into this. Got an OBD2 reader and a new laser temp gun, and monitored reported coolant temp sensor data vs. head temp (should match), thermostat inlet temp, and then thermostat outlet temp on the radiator hose in 1 minute intervals on a cold start. Saw thermostat opening way early at 160F. Not sure when the stock is supposed to open, but either way it's opening early, and staying open below where it should, thus the truck is not maintaining temperatures. Done deal it's the thermostat, which is what I had thought it was in the first place! The coolant temp sensor was probably always fine!

I think it's due to the strikes, to be honest! Saw this on a parts website. I might just have to put the questionable MOTORAD in it for now.

UPDATE finally got through to the parts counter guy at my dealership. He confirmed the parts are "massively backordered" and that they have 8 on backorder right now, but no idea when they're coming in. FFS.

Checking in. Mine need replacing sometime soon also and wondering if they can be had for cheaper. They're "seeping" at the moment. Not sure what the forum consensus is on them, but to me they're AMAZING. Not gonna do a "delete" but was definitely "shocked" at the replacement cost. Had no idea they cost that much money.

Hi all, First real issue on my 2018 Suburban 5.3L at 86k miles. On a road trip over Thanksgiving, I noticed it wasn't holding operating temps. It has always stayed dead nuts on at 210F indicated no matter what (hot/cold/towing), but on this 900 mile trip it was fluctuating between about 190 to 205F indicated. It would touch 210F and never go above that going up a long grade or if I had to get on it to pass someone, but otherwise kept fluctuating between 190-205 indicated. My thoughts. Thermostat stuck open, and will open as much as it needs to to avoid overheat, but won't close up for whatever reason resulting in a mild underheat and very slow warm-ups. Took to dealership (I hate these guys), they offered to throw a temp sensor at it (???). Saw here on the forum that these can go bad too, so said okay but was wondering. Honestly, I just wanted to throw money at it and make the problem go away also, but sure enough it's doing the same exact thing today so just wasted a bunch of money for nothing. Digging in now, and apparently NOBODY has the OE thermostat in stock?? GM GENUINE PARTS WATER PUMP OUTLET ASSEMBLY WITH THERMOSTAT GM Part # 12674639 ACDelco Part # 15-11125 Not online parts sources (RockAuto, O'Reilly, NAPA, etc.), and not local dealerships either, hence offering to throw a temp sensor at it and hoping it would fix it, since they apparently didn't have any thermostats (GM Parts online says no for all area dealership, but still trying to get in touch with the parts counter guy to confirm.) What gives?? Is there any place you can get the OE thermostat from these days? Summit Racing listing actually showed an estimated shipping date of MARCH 2024? What the actual f*?? https://www.summitracing.com/parts/ado-15-11125 Rock Auto had these MOTORAD thermostats available? Are these any good? I searched and found one thread here where someone who got the stock 207 degree t-stat reported the engine running too hot, and actually had to get the cooler one and then it was fine. No idea if that's the norm or just a fluke? What else is there? https://www.rockauto.com/en/catalog/chevrolet,2018,suburban,5.3l+v8,3438969,cooling+system,thermostat,2200 Also, for those of you that have scan tools, if the gauge is showing 190-205F indicated, do you know what the actual coolant temps are for that? I'm assuming the gauge stays parked at 210F across a wider range. Just wondering. Going to be putting 2-3k miles on the truck over the next month, so want to get this sorted ASAP without getting ripped off again, or having to put a flakey part in. Thanks for the help!

150-200 kWhr batteries and 800V charging systems (ala Porsche Taycan) are where it will be at for electric trucks that can tow. 200 kWhr batteries would probably give a reasonable range for a pure EV, and 800V charging systems will charge twice as fast as the Tesla 400V superchargers, or let you charge a 200 kWhr battery in the same amount of time as a Tesla 100 kWhr battery @ 400V. What I think would be interesting is a series-hybrid truck with an all-electric drivetrain (think Volt), enough battery capacity to keep things going for quite awhile (maybe at least 100 kWhr), but then a beefy enough ICE to keep things going when you're pushing the limits. That 2.7L turbo-4 might work pretty well for that. A lot of weight and cost and complexity there, but it could work. These first gen EV trucks will just get their foot in the door with whatever they can do, and will probably have pretty limited towing capabilities as far as range, but things will only get better from there on out. I don't think gas and diesel powered trucks will be going anywhere anytime soon. There has to be a robust grid of 400V/800V charging stations or whatever they end up standardizing on everywhere including out in the sticks for these things to take off, and then our entire electric grid will probably collapse long before then. Lol. EV's are cool, but our grid won't handle a critical mass of people all charging their EV's overnight.

The 8-speed transmission was left half-baked for the K2xx platform trucks, because GM was working on the joint 10-speed project with Ford at the same time. They claim to have improved it a ton in the T1xx trucks. A fluid change might temporarily mask some issues, but I seriously doubt it's going to fundamentally change the nature of the transmission. It is what it is. If it's going to worry you, just look for a Suburban or Yukon XL with the 3.42 gearing with the 5.3L/6-speed combo. It's nearly as good and without any of the issues. The 6L80E is pretty solid.

2018 Suburban purchased Nov 2018 (so probably a late MY2018 build). Not on the recall list.I have adaptive cruise and the forward collision warning / auto braking stuff, if that matters.