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Hello, ive read many threads about coolant crossover tubes and block offs but i cant seem to find the correct answer as they all seems to think different. I am swapping a 5.3(100% stock) into a 1989 c1500 obs truck. My question is can i block off all 4 corners of the coolant crossover tubes or do i need to have them? I am using the stock c1500 radiador and i dont know where to route them to. If i cant block them off where can i connect the tubes to? Can i connect them in line with on of the heater hoses? Ill include a pic i drew from how i have the rest of the coolant so far.
I like the tapped water pump approach, but this worked for me. It is slightly less clean.
I made this with aluminum tubing and a -6AN aluminum bung I tigged to the coupler tubing. I didn't flare the tubing, but did push several inches in to each end of the hose.
Note, when I fill up my system, the air naturally bleeds out without doing any special. I don't even have to start the engine to get the air to bleed. I'm guessing since there is so much vertical between the top of my radiator and the block and the hoses are routed with significant vertical rise.
You can absolutely block all 4 off if you wish. You just need to make sure you get all the air out each time you fill the system. Quite a number of people routinely block them off. The block offs are O ringed so it doesn't hurt them to pull and reset. Even with them vented to the water pump I pull one every time I fill or drain the system. Makes both operations twice as fast.
Having said that it is cheap insurance to plumb them in somewhere. It just has to be into a pressurized part of the cooling system.
Jags that runs sells a fitting that hooks into a hose
Ok thanks guys. I need to put a section of pipe into the hose to mount a temp sensor so i guess i could weld a fitting on there as well to put the hose into.
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Coolant crossover block off? 
