99 k1500 overheating

[DESHOOTER]

Cannot figure this out all sensors and senders are new thermostat new. I have the issue and a few questions.

How much should cooling system hold?

Truck heats up to line between 210 and 260 starts to perform poorly and overheats or stays just at overheating. Lots of new stuff recently cause she's got miles and chasing a hard start rough idle issue. All O2s are new, spark plugs,wires, rotor,cap. Coolant looks murky but doesn't seem to be losing any. Heat won't work. Bypassed heater core and flushed it, seemed clogged left it bypassed still overheating. Disconnected radiator flushed it separately some funk but not alot. Removed thermostat stuck hose In engine full blast ran engine. Some funk not alot or what i expected. Buttoned it up filled with 50/50 started it thermostat opened added more......with it open and overflow filled to cold line it took 2 gallons??? Book says 17.5 quarts isn't that well over 4 gallons? Excuse the ramble little overwhelmed. Any helps appreciated

[txab]

You need to remember you're not getting 100% of the old liquid out using your method. Still water trapped in the block, that's why you can only get about 1/2 of the expected amount back in. Best to use 100% Dex when refilling after flushing with clear water. Be sure and check fan clutch for proper operation. You could still have a partially clogged radiator too. Make sure you have no trapped air in the system

[barry G]

enough to clog is bad.

you can feed the coolant side oil..and not the other way.

 

seems you got some bad news no matter what it is.

I found these problems to be headgaskets keeping compression..and not much else in a good direction.

 

you also got coolers inside the radiator sidetanks. that could be a source of goop.. if one of those leak oil or atf internal.

[DESHOOTER]

Hello. Thank you for the replies. What method should I use to get all the fluid out of the block? How do I know if I have air in my system? Truck sat for 9 months with dex in it.

[txab]

There are block plugs that can be removed. I just flush block with clear water until I'm satisfied. Then flush with distilled water. About 50% of the water will remain in block. Then add 100% Dexcool until I reach the 50% amount for coolant, then if necessary top off with more distilled

[alpinecrick]

The knock sensor is probably the lowest point in the water jacket and the easiest to remove. Located in front and below the starter. Remember to use some thread tape/sealant when you screw it back in.

[alpinecrick]

And skip the Dex and fill it with regular antifreeze.