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  • 1 Post By KarlzEE Bebout
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  #1 (permalink)  
Old 02-12-2022, 10:45 AM
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Default Hex Freeze Plugs

Hi guys I could use a little help with #634. It has 427 Cast iron side oiler. I have some noticeable leaking from several freeze plugs. They are hex screw in type. Do I need to drain the entire system to reseal them? Or can they just be unscrewed and resealed? Is there a certain sealer I should use? Should I buy new plugs or reuse the old ones? They don't look rusty. Any help and advise would be helpful.
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Old 02-12-2022, 04:33 PM
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When you unscrew one, it will mostly drain the system. It would be much cleaner to drain via the radiator petcock first.

John
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Old 02-13-2022, 07:19 AM
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BTW, I'm sorta doubting that what you are referring to are "freeze plugs" but rather they are drains. If they are threaded in, do you suppose that they would release the liquid's frozen pressure?
Back to your actual question: I've had good results using 3-4 wraps of QUALITY teflon tape on the threads. Also, ARP makes a "thread sealer" that must be excellent to carry the name. Lastly, plumbers have been using "pipe dope" to seal threads for decades, if not centuries. My 2 1/2Ę worth.
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Old 02-13-2022, 08:07 AM
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Side oilers do have threaded "freeze" plugs on the sides of the block.

I worked in automotive manufacturing for many years as an engineer. I was specifically involved with the 2007 Ford Powerstroke.

The "freeze" plugs are used to get sand and excess cast iron out of the block at the end of the casting process. They are not intended to protect the block from freezing.

John
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Old 02-13-2022, 10:43 AM
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I think they are actually for both purposes but their usefulness to protect a block from freeze damage was pretty much negated with the introduction of antifreeze many decades ago. The manufactures just stuck with the standard friction fit core plugs as they were cheaper than threaded plugs and under normal conditions, served just as well.
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Old 02-13-2022, 01:05 PM
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I can't wrap my head around the idea that threaded plugs would blow out if the coolant expanded due to freezing. Maybe they would be the weaker point but I'd think the block would crack sooner than the threaded plugs would be forced out.

Has anyone actually had the experience?
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Old 02-13-2022, 01:25 PM
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I don’t think your getting the point. They are no longer considered freeze plugs because frozen engine blocks are no longer a concern in the industry due to the widespread use of anti-freeze. Now their sole purpose is to remove mold casting sand from the coolant passages at the foundry. Ford must have figured a friction fit plug might be a reliability issue in a engine that would be run extensively at high rpm (including the water pump).
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Old 02-13-2022, 01:53 PM
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Quote:
Originally Posted by DanEC View Post
Ford must have figured a friction fit plug might be a reliability issue in a engine that would be run extensively at high rpm (including the water pump).
No. They're actually called Welch plugs. And for your absolutely arcane automotive factoid for the day, read this:

https://www.britishcarweek.org/welch_plug.html
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Old 02-13-2022, 05:37 PM
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That is interesting.

A lot of great engineering ideas are mistakes or accidents that show a better way.

John
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Old 02-14-2022, 05:13 AM
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Wow guys. Ok guys. So to fix the Freeze,Welch, hex clean out plug leaking issue. I must drain the radiator remove plugs with a hex wrench that I will make, and then seal each plug with a high temp rtv? Keep in mind that area gets kinda hot. Is this a common issue on SO?
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Old 02-14-2022, 09:41 AM
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Quote:
Originally Posted by Lalmeida617 View Post
Wow guys. Ok guys. So to fix the Freeze,Welch, hex clean out plug leaking issue. I must drain the radiator remove plugs with a hex wrench that I will make, and then seal each plug with a high temp rtv? Keep in mind that area gets kinda hot. Is this a common issue on SO?
I have never personally touched a side oiler's screw in freeze plugs. But since no else is going to give you any help, I'll refer you to this topic on the FE forum: https://www.fordfe.com/screw-in-free...nt-t95234.html
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Old 02-14-2022, 01:31 PM
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I suspect leaking isn't common. Patrick's link has some good suggestions on sealing the plugs.

I noted one guys comments that the screw in plugs were to make the block stiffer.

That makes sense. Ford had bottom end issues on 427s in NASCAR. A screw in plug costs more, but if it allows you to win races on a low volume engine, then that is a good reason.

John
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Old 02-15-2022, 03:58 PM
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Default Core Plug Removal

This screen shot is from Steve Christ's book titled HOW TO REBUILD BIG-Block FORD ENGINES, pg. 69.
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Last edited by 601HP; 02-15-2022 at 04:01 PM..
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Old 02-15-2022, 04:19 PM
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Quote:
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This screen shot is from Steve Christ's book titled HOW TO REBUILD BIG-Block FORD ENGINES, pg. 69.
Thx 601. Believe me I donít want to remove them. But I guess I have no choice, I have to either live with the leaks or replace them. Anyone know if they are NPT or straight pipe?
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