I am having to replace my heater core this weekend, so I figured I would to a thermostat and coolant flush as well. I did one before, but didn't install the drain-***** in place of the block coolant plugs. Does anyone know the size/thread pitch for the drain plugs? Any suggestions on which type to use? Do the treads need tape or dope to seal them?

Thanks

 

Pretty sure it's 1/4" NPT

Mike

 

From a post several years ago...
BajaGringo Block Drains

The block drains are just 1/4"npt pet*****, available in the "HELP" section at the auto parts store. You need a 9/16" crowfoot socket that fits on a socket extension to reach in to tighten them (There's no room for a reg open end wrench). Then, cut up an old spark plug socket to fit over the petcock to loosen/tighten. Once they are loose, slip the 3/8" rubber hose over the end of the petcock and continue loosening the petcock (with the other end of hose in bucket). Intstalling these is still messy and a bit of a hassle, but NEXT TIME it'll be a lot less messy and a lot easier. Smear 'em with anti-seize to make sure they turn 'next time'. I've already had to use mine because when I had the radiator 'rodded' they didn't have the right kind of antifreeze, and I was 200 miles from home. So I needed to re-flush the system and re-DCA it. This makes saving/reusing the expensive DCAs/antifreeze possible if you use CLEAN BUCKETS. I bought a special funnel that snaps into the radiator fill, and use a metal spray paint funnel/filter/screen just to make sure nothing too big gets back in there. Yeah, I'm a little '**** retentive', that's probably why my eyes are brown. BajaGringo

I installed these on my truck. Not sure if I did the straight pet***** like the radiator, or a 90° thing with the valve straight out, but it drains down, I can't remember right now, but I got them at Napa.

 

I bought these exact ones. They fit both my 7.3 and 6.9 blocks. LOVE THEM. Stick a 5/8" heater hose on the end and flip the valve and no block mess. Just used them today again.

https://www.mcmaster.com/#4112t21/=17gk98p

 

Thanks. That will get me what I need.