Radiator thread size

[Slow Steve]

Does anyone know the thread size of the fitting below the filler neck.. not the two transmission lines. but the other? I'm doing a LS swap and want to use that port to run the steam port into it there like the stock Tahoe rad. TIA!

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[packer0440]

That’s supposed to be a drain plug. Not sure if anything else will go in there

 

[Slow Steve]

That’s supposed to be a drain plug. Not sure if anything else will go in there

That high up?

 

[Slow Steve]

That high up?

The stock Tahoe rad uses that same spot for the steam port vent. I'm using it on another 5.3 swap without issues. I just didn't know the size on this new rad (different mfg).

New Rad 90 Sierra

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Stock Tahoe rad

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[RichLo]

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Which fitting? The top right is the overflow and heater core return which doesnt have a threaded fitting. Bottom left is the drain where that plug should have come from.

 

[RichLo]

Your too fast, thats the heater core return. With an LS swap you'll have that in the block. You could use that for a steam return port just like the factory 5.3 radiator

 

[Slow Steve]

Your too fast, thats the heater core return. With an LS swap you'll have that in the block. You could use that for a steam return port just like the factory 5.3 radiator

Yes sir, I found the thread size. M12x1.25. Ordered a barbed fitting for the steam port. This way it's just like stock and I don't have to cut the upper hose or drill and tap the water pump. Thanks!

 

[Slow Steve]

M12x1.25 if anyone is interested. Looks like it'll work just fine.

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