How to bleed coolant?

Here's some extra info on the cooling system flow, and other components. I don't see a lower intake manifold, like on a GM with a low manifold that bolts down in between the two heads, but this engine is a complex build for sure, there is a smaller bleeder on the pump itself, I'm not sure if there's a hose to it or if it's for just bleeding air right at the pump, but it's in diagram 6.

I am going to test the ECT in cold and hot water. What should the ohm readings be in cold vs hot water?

The plug on the front where the thermostat is reads ground on one pin and 3.5 on the other .pin. Am not seeing ect 2 on any site, but disconnecting it made no difference in reading still reads 64f.

Okay, you should definitely be reading 5volts on one of the wires when the sensor is unplugged. It looks like the Yellow wire should read 5volts, the other wire is the sensor ground through the ECM, there is a TSB that came up, I will post it, I havent gone through the entire bulleting yet, but it does mention a bypass hose that it supposed to help with airlock, which will cause the ECT to read incorrectly if air is trapped at the sensors location, ECTs cannot read the temperature of air, only liquid, but a low 5volt reference is concerning as well. One temp sensor is located on the front of the engine and the other on the rear (diagram 2) just above the flywheel area. This is the OEM wiring diagram that also shows two temp sensors, you may need to cycle the key for the temperature to change, or it might be the other sensor, I'm not 100% sure on the two sensors, if that's for a different engine setup, but it's just what I'm seeing, let me post this TSB though, I think it will resolve your coolant issue.

So, here for this TSB they want another hose with 2 T fittings run to the coolant expansion tank to help bleed air out of the system. I would think you could do this without having to purchase these parts from the dealership, you would just need to find a couple cooling system T fittings and a section of coolant hose with some hose clamps to complete this TSB, even if you're not getting the codes setting P0126-26/P0128-00, obviously there's an issue with air pockets in this vehicle, that's giving you a lot of problems.
Diagram 12 explains the operations of the two ECT sensors.

wow, lots of great info. At least I know this MAY not just be me lol. I will get the fittings and hoses and get it done. I will also see if the back ECT is one that reads, cause whether I remove the front or leave it corrected it does not affect the readings.

Oh and i was able to get 4.5 volts on one of the connectors. It was fluctuating based on how i touched it. what's the point of the second ect then if only one reads temp?

I think that's why you're not seeing any change in the signal on scan data, and no I don't think the air being trapped in the system is your fault by any means. There are so many tiny hoses running all over the place, I've worked on these vehicles before, and I think they are just overly complicated. So hopefully this extra hose will allow more air out of the system, I would still use the vacuum bleed/draw down system. It's very effective and makes filling so much easier. Here's the ECM connector pinout so you can check the 5-volt reference at the ECM itself, the ECT sensors will need to be unplugged to check it with the key On, engine Off. It might be that the other ECT sensor is possibly faulty.

It looks like there are two ECT sensors to verify the thermostat is working correctly, so probably one sensor on each side of the thermostat in the coolant jacket, this way the ECM can set a thermostat code if it doesn't see the correct change at certain temperatures.

If you're moving the connector and it's affecting the 5volt ref, there is most likely a bad connection or wiring issue inside the insulation at the connector, even 4.5volts might throw the ECT's reading off somewhat. That's something I would investigate further.

will check it. No, it was more my hand moving and the voltmeter pins being too thick to insert.

I am also getting a 64f reading and then it climbs gradually on scanner, so sensor works, if it was fluctuating on scanner I would have thought wiring, but I will open it and confirm.

Going with the TSB repair sounds like a logical fix, there must have been quite a few complaints coming in about the coolant system for them to post a bulletin on it. But let us know how it goes.

I checked the TSB and unfortunately the parts/kit is not available anywhere anymore. I know it's a couple of fittings but knowing what size is the issue. Are there T fittings that can have 2 ends with some size and a 3rd with say smaller size? because the 3rd end would need to have a smaller size hose to go to the coolant expansion tank hose and attach o it, but its smaller in diameter.

I will take a look, since I'm checking on parts for another vehicle right now anyway. Basically, you need to find T fittings that can take the heat, I know when I go to AutoZone or local parts store for basic stuff, they have a section where they keep pretty generic hoses and random parts that are not for any specific model. Or do a google search for something equivalent to what you need. But I will look for a few minutes here. Sometimes you have to get creative if parts are not available from the dealership.
What size do you think you need for the T on the two fittings that are the same (outside diameter)? And then the smaller of the 3 fittings?
This was the non turbo engine as well, correct?

rockauto has a section at the top of their page called "Tools and Universal Parts", they have some T fittings and also some reducers that could be installed into a hose to adapt it to whatever is needed, then could be hose clamped down, this is just an example of what you could do, I didn't really looks into what the specs and sizes are for these, it was just a quick search, but a google search for a coolant T fitting might yield better results.
The 2nd one is from AutoZone that has two the same and one smaller.

This coolant T fitting is actually from Walmart of all places. so, there are definitely fittings with multiple size hose adapters out there.

it is a non turbo. I will send you a video to show you what I mean. Is there a tool out there that is used to measure hose sizes on the inside? It's going to be hard to go back and forth to the store and buy 10 different ones before I get the right one. There is not much pressure on this heater core hose, same for the expansion tank hose.

Are you not able to measure the hose with it disconnected?

I have no way of doing that.

Okay, this is the cheapest micrometer ever, they sell them at harbor freight for less than $10, but it can measure inside and outside diameter. It's not designed for mechanical measurements that need to be super precise, but it will work for your needs, I use this thing all the time when doing 3D printing. The smaller side facing kind of up on the left side is for taking inside measurements, you can use the jaw side for measuring outside diameter if needed.

Attached.

Also, say i find the inside diameter of the hose lets say its 1/8 what numbers should the fitting be? Also 1/8?

Yeah, the rubber hose should be able to stretch enough to fit over the plastic fitting, and then a hose clamp around it. I check out your videos really quick.

Yeah I saw the TSB for the hose installation,. it seemed like the basic idea was to have a higher section of hose where any air in the system would be able to rise to and then exit into the expansion tank. Thats why they put bleeder screws at a high point in the cooling system, the issue with the cooling system right now (stock) is that air pockets are getting trapped in a location where there is no higher location for the air to go, technically the vacuum down bleeder method is supposed to take care of that, the downfall I see to the method is some coolant leaks happen under positive pressure and can be missed when its under a vacuum due to the negative pressure, or lack of pressure.

In the 2nd video that whitish section that the hose came off of looks to be about 5/8in or so, you could just measure that with a tape measure, then you'll know the outside diameter of that section you need to fit a hose over and the size T fitting you need. It looks like with that bleeder being there as well, that will now be the highest point for air to escape, even from the expansion tank which will help.
Next you will need to see how big the inside diameter of the hose go to the expansion tank is.

Yes the end where you circled should be the same size as the one in the expansion tank, that I should be able to figure out. Let me dig into it and see. Thanks

Yes, the hose coming from the heater core hard line was probably a quick disconnect, so just put a regular hose clamp over that once you get the T ready and a short piece of hose to go in between the T and heater core section, it looks like 5/8" to me but measure it with a tape measure to be sure, just remember to run the hose under the air intake boot so any trapped air will travel to the bleeder screw.

Was finally able to get some hoses and fittings. Deleted all codes abd started it after i filled the expansion tank and removed the bleed screw on top of it after i capped it, then added more water and started it. 2-3 minutes later i got heat, barely opened the bleed screw on top of the heater core hose and let some bubbles out. Fan didnt come on when i started the truck like it did before so that was good. Temperature climbed to 122f which was gradual. But then noticed some water coming out of a small hose so turned it off. Its this hose which is new. The small end circled is where water is shooting out of and the end is not all the way in, tried to oush it more but its not going maybe ill wait till its cool and not spraying. Is there a way to find out how this thing fits in and doesnt come out? Is there like a rubber grommet that holds it in? This is a new hose because my helper broke that hose so he replaced it but i cant remember how it comes off or goes in. He is done, done few bad jobs so he is out. So am trying to find out if all it is is a grommet inside the hole where that hose goes in. The end of the hose has a small nipple basically.

it looks like a quick disconnect fitting, some of them that appear to not come out, meaning the part that looks like a clip on the receiving end of the other hose, need to be squeezed together to get them apart, it should clip in when pushed on if its not holding, then the clip is not grabbing onto that outer ring section, if it was bought from an aftermarket location it may not be the correct fit. Parts from amazon and such rarely fit correctly, but it should snap right into place.

No and 100% sure it's the right fit, but the part it goes in is just a white circular rubber piece, not seeing anything where it would clip on, unless the idiot threw it away when he removed it. it could be a 2-part piece or the clipping part broke. Just don't know what it looks like and whether it's part of the water pump assembly or can be bought separate.

is this a hose that you added and is not stock to the vehicle? That plastic end with the round ring on it is definitely a quick disconnect line, a rubber hose wouldnt go on the end of that, it would be another plastic piece with a clip to secure it in place.

No, it's original. Here are pictures. The helper who did install it may have lost the piece that is supposed to be there for it to go in and clip. all I see is this. Not sure if there is a piece that can be bought or some piece of it broke off.

Can you identify the section of hose on this diagram youre referring to, I know it says thermostat to engine. But is it part 19 on the diagram?

Okay, it's supposed to go into that smaller opening in the first picture?

It looks familiar, the plastic tube might be missing a locking clip on it that slides over the end of the tube and is one of those that requires it to be pushed together to get it to unclip and come out. Not sure if I can find a picture of one, I'll try though.

I was thinking of something like this, but it does appear something is either missing or broken off where it goes into that hole, it almost looks like there is a metal insert in that location?

What is this part? If that's a section you can identify, do a google search for that part and see if you can find a picture of the original, then you'll know what might be missing, there has to be something that clips around the end of the that plastic tube to hold it in place.
I found this on a search but there is nothing on that end of it.

That is where the nipple goes into, but yes, I am thinking a locking pin of some sort is missing and i can't seem to find it. Yes, its number 19, that is the thermostat to engine hose. But i can't find anything on Google.

I get this when i search which i doubt has anything to do with it.