stu_pidasso

Unless its a Chrysler made V8 lol. That was one of the speculations on why their Hemi V8s were chewing through cam shafts at one point. Pre COVID, Chrysler had about an eight week backorder on cam shafts for the 5.7.

When were the spark plugs last replaced? I bought a truck straight from auction with a P0301. It would idle rough at stop lights and stuff. Put a new batch of plugs in, now the truck runs like it just rolled off Arlington Assembly. Those fuel pressures are within spec. I know some stuff says 58 pounds running, and it should not run that much under no-load-pre-start charge (60psi), but 44 ain't bad. Fuel pumps either work, or they don't. The 69 (hehe) code is related to manifold pressure, and 641 has to do with a few grouped sensors that try to read a variable. This would be three wire sensors, sensors that would tell the PCM how much pressure, how much temperature, etc, not like a binary or on/off sensor that would tell the PCM a condition is met. Knowing that, and knowing 641 is coupled with P0069, I would look at the MAP sensor to start, things that tell the PCM whats going on in the manifold, MAF sensors, intake gaskets, air filter. ****** like that. The key to troubleshooting is to start small and eliminate the easiest, cheapest, and simplest part of the system thats giving you the problem. Work from the bottom up, not the top down.

Personally, I wouldn't worry too much about the ticks these engines can make. It can tick from loud injectors. It can tick from leaky exhaust manifolds from broken bolts (and go away when the engine is warm). It can tick from lifters for a few minutes and then go away when the engine warms up. Unless it's loud and sounds like a tractor, I don't pay attention to it. I also don't care about the oil that goes in to these things. I buy whatever is on sale. I am an operator of an oil refinery and, well, everything we make is to a spec. If Shell, Mobil, or Total wants to go above and beyond that spec with additives, good for them but I am not paying for it unless its competitive with regular ol' DEXOS, API, ILSAC, and whatever other spec standard made cheap oil. I know that sounds careless and sacrilegious but, come on, it's an LS, one of the most robust and reliable V8s ever made. It's not a Ford Triton V8.

My 2006 'Do had the weight spec in the manual too. I haven't looked hard enough in my 2011 Suburbans manual to see if its there too though.

Throwing parts at issues is a costly solution that does not always net the result you're looking for. Be weary of that. When troubleshooting problems on vehicles its best to start with the simplest and most basic steps first. In this case, it's the wiring. GMT900s can have weak wiring harnesses in the door to cab rubber boot. Start there first and confirm no wires are split or splitting. I had an airbag sensor issue for the rear drivers side passenger door that was fixed due to a broken wire. The drivers door, when closed, did not trip an SRS code, but when open would. My friends 'Do would not play music through the passenger door when open, but worked when closed. A spliced broken wire fixed those issues right up. Start there first, give the wiring a good inspection and it may be a cheap fix.

On the GMT900s the door wiring harnesses are known to crack and split causing all kinds of goofy things. Unsure if this kind of problem is just starting to surface in the K2s. Depends on how deep you want to get with this, but if it was me I'd inspect the wiring in the cab to door harness, that flexible rubber boot. I've fixed two airbag issues and a speaker by splicing broken wires back together on one truck.

32 and 150 pounds for 70F are normal. But 200 when you rev to the point it cuts out is not. Do not bypass the pressure switches, especially after you discovered the high side cranks out 200 pounds. Pressure switches are not a computer nanny. They are very, very necessary. If you need to bypass them as part of troubleshooting, only do it after you confirm the pressure ranges are normal. You run the risk of over pressuring parts of the system, blowing seals etc. Has any work been done to the AC like new gas or a gas top up? Does the condenser fan cycle and can the condenser get good air flow? Does the compressors clutch cycle properly? Or does it just engage and stay engaged? If it cycles properly, there is a chance theres a restriction somewhere. When the high side goes to 200, what happens to the low side pressure?

The thermostat only goes in one way, so it's unlikely you installed it backwards or upside down. One bad thermostat is a possibility, but two is unlikely, not unheard of, but unlikely. Did you try running the heat on full to see if the heater core is getting flow? The blend door actuator is what controls the heat in the cab, not a valve on the cooling line. Air locking them or keeping an air pocket in there is harder because there is no valve albeit still possible. But if you fill the cooling system up, and it's blowing hot air, it tells you right away some level of circulation is happening. Like I said earlier, it's easy insurance to prove something is moving around. When you refilled the coolant, did you leave the cap off of the reservoir while it was getting up to temp? Did you top it up as needed? Your cooling system needs 15.7L of coolant, is that how much you put in? You'll need five 3.78L jugs, using four completely and a quarter of one.

Dang, this problem is ballooning lol. Take a break. Come back to it tomorrow. Grab a pair of vice grips and back whats left of the bolt out. Buy a new one at the dealer or get a handful at the junk yard. Stuff happens. Stuff can be fixed.

Is the core lower on the K2s? On the 900s and 800s the supply/return hoses are marginally higher than the expansion tank cap making the hoses the high point. Turning the heat and fan on high is an extra step, but its a cheap insurance that coolant is at least flowing somewhere.

Well, don't go tearing apart the water pump and replacing it right now. This is a huge step that you missed the first time around that can cause exactly what you're experiencing. In order to bleed the heater core, the best way is to start your truck and set the heat and fan speed to high, as high as it will go, and let her rip for a few minutes. Air locking a closed loop can do exactly what you have going wrong. 1AAuto's YouTube has a lot of GM content, and has videos on how to bleed the system properly. I know its a GMT900, but the concept is the same, and the engine set up is mostly the same. Do it right this time, and if you're having trouble still, then start working it. Nah, there will always be pockets and areas of the cooling system that do not drain out even though everything is higher than the drain. Old Honda D series engines rads sit way lower than the block, but when you drain the rad the block is mostly full. Makes for a refill that requires care. I would personally use Dex-cool, I try not to screw around with coolants and just buy it right from the dealer. Your owners manual should tell you how much volume you need for coolant, if it wants 10L, and you put in 7L and the reservoir is full, well...

When you refilled the cooling system, which coolant did you use? And did you bleed air out of the cabin heater coil? In your idling, driving, and revving experiments, does the coolant level drop at all? Are you losing coolant? A water pump doesn't have to leak to be bad. The impellor can, and has, spin/crack off the shaft and not pump anymore. I agree with CamGTP, if you're positive you used the right coolant, and you properly bled the entire cooling system including the heater core, then something is prohibiting the coolant from being pumped, or allowing it to dump the heat. The rad is easy to check, pull off the supply and return hoses, and you can check for communication, water goes in, water goes out, but that does not guarantee it can move the right amount of coolant through it, ie proper flow rate.

100%, these recharge kits with sealants in them are no different than the rad stop leak bottles you can buy. There is a chance they solve the problem, but they will leave goo everywhere and eventually when you decide to solve the issue permanently, you may have a mess to clean up. Not to be rude, but you bought it, that's why it's sold. People buy it. Nothing wrong with it if you want a quick fix or a slow leak you just don't want to pay to have fixed and delay the inevitable. My old GMT800 'Do had a leaky compressor. Took a year for it to leak out, so I'd just top it up with 134 in May. Depends on how serious you want to get with this. If you want to do it right, find the source of the leak and fix it, vacuum, get a bottle of 134 and a scale, recharge to the right weight, and ensure pressures are in the right range. But I wouldn't worry too hard about moisture at this point, sounds like not all of the gas was lost when the problem surfaced. Id probably blow a little bit of gas off to try and get it back to a 1.8lb charge, but I'd say you're okay to forget about it and enjoy the cold air.

I've had numerous GM trucks across three different generations, both personal and company. They all seem to do this, averagely hover around 40, move between 20-60. I wouldn't worry about it personally. If the gauge pins out or barely reads, then I'd be interested in finding out why. But if it is steady and occasionally bounces around and still is a healthy pressure, then its no cause for alarm.

What makes you want to find this relay? I ask because this system is all tied in to the CANBUS/BCM, that's how lane change tap turn works etc... So what is the issue you're having?