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Old Bastard !
Joined: Fri Dec 22nd, 2017
Location: California USA
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This is a 4.0 identical to Mikes, the first page shows several "freeze plugs"
https://ford-rangers.com/forum45/2176-1.html
You know half the nation thinks that these were put there to pop out if the anti-freeze gets too lean to somehow save the head/block from cracking.
They are actually part of the casting process for removing the sand after the iron is poured. They machine them while the head is on the mill and seal the holes with extreme press fit core plugs. The thinness of the core plugs is why they tend to rust quicker than the thick casting.
If this is of interest to anyone do a search on "cope and drag" it will explain the mold process. I designed a couple sand molds back in the day.
Interesting, I didn't know that was their purpose.
I have always called them freeze plugs for the purpose which you stated but I have an engine that popped two of them, the block cracked too, so they didn't help but it make sense now.
____________________
Ltr,
2003 EDGE, Std Cab, Steppie, E4 Red, 5sp, 4x
5" SuperLift, 33" x 12.50 x 15"
Hurst Shifter
Mod'd Backrack to fit Steppie
Front and Rear Bumpers by Custom 4x4 Fabrication, OK; now Mike's Welding and Fabrication.
Working on more Mods, just need more time, longer days would work !