he said he would charge 45 to replace each plug

 

Shouldn't be more than 3 hrs. labor to replace all of the block freeze plugs, refill and pressure test coolant system.

 

droped it off around 1 and its 3 now, he said he might have to keep it over night

 

they were designed to keep your block from cracking.

 

I don't think that the purpose of the plugs is to pop out when freezing. They are for the casting process, to get the sand out. Anybody have a definite answer on this?

 

Definition of freeze plugs: An expansion plug located in the side of an engine block that is supposed to protect the block against freeze damage. Water expands when it turns to ice, and if the coolant doesn't have enough antifreeze protection it can freeze and crack the engine block. The freeze plugs (there are several) are supposed to pop out under such conditions to relieve the pressure on the block. Freeze plugs can often be a source of troublesome leaks as a result of internal cooling system corrosion. Ease of replacement depends on accessibility. aka the name of them "freeze plugs"

 

xstrange alluded to this issue:

"One thing to remember about leaking freeze plugs: Usually, the reason one leaks is because it's a steel plug and it has rusted out from the inside. That's usually caused by previous owners filling it with straight water or not enough anti-freeze."

To elaborate, NEVER use tap water in your cooling system. Best to use about a 50/50 mixture of distilled water/antifreeze. By the way, I don't trust the 50/50 premixed antifreeze, as who knows what they use for the water part. Not to mention, they're kinda hosin' you on the price.
Just my $.02,
Gene

 

It would be interesting to trace the history of the explanation of "freeze plugs". The whole story that the purpose of the plugs is to pop out to prevent cracking of the block if the coolant freezes has been passed back and forth for at least 50 years. Everybody says it. But it doesn't make a whole lot of sense technically. Sure, if water in the block freezes, it will expand. That's physics. But if the water has gone solid, it will expand against all of the internal surfaces. The plugs may pop out, but the ice will continue to press out and crack the walls anyway. If you've seen a block that's had water frozen in it, they're usually cracked anyway, even if the plugs popped out.

On the other hand, if you say that the purpose of the plugs is to pop out to relieve the water pressure before it freezes, that doesn't make a lot of sense either. If the water pressure goes too high, it'll just back up through the system and flow out past the radiator cap into the overflow tube. Or, it would blow a leak at a hose joint long before it would reach the pressure needed to pop out a plug. I think that this is just one of those automotive legends that started somewhere and took hold. It's just believable enough that it gets believed.

The official name for "freeze plugs" is core plugs. They're cheap metal plugs that are used to permanently fill holes that are needed in the casting and machining processes for making the block. The "core" is the male image of the complex water jacket chambers in the block. The core itself is molded from a mixture of plastics and sand. It's held in place inside the mold by a series of fingers that extend through the holes in the sides of the block. After the cast iron is poured in and solidified, the core is dissolved into a slush and is flushed out of the inside of the block through those holes. During the machining operations, the holes are bored out to a good sealing surface, and the core plugs are pressed in to close them up. In some places, core plugs are used to plug holes that are needed in machining operations, such as at the far end of a camshaft bore, or where a blind oil passage is needed.

 

well i found some stuff out today. who ever "rebuilt" the engine used temp freeze plugs all the way around. so i got the one fixed (129.00) and he made an over flow kit out of an empty anti freeze bottle. he also told me the reason why my truck has been goin into N while driving..the shop that put my glass packs in put the exhaust to close to the transmission linkinge thing. he also told me to get an electric ignition set up for the truck, and look into rebuilding or replacing my carburetor....thats in for now i hope.

 

True to a certain extent. Initially, at the foundry, the plugs were known as core plugs, used in the casting process. Later in the production process they became known as expansion plugs, which served the secondary purpose of alleviating pressure in the event of freeze over. The radiator cap was designed to relieve pressure from the heated expansion of liquid, not expansion pressure from a solid form such as ice.

 

That's my point, Bobby. Somewhere along the line, somebody started claiming that core plugs have this other function as "freeze" plugs. Who started it? Was it a sales claim by manufacturer like Ford? An aftermarket parts supplier? I dunno. But where's the engineering to back it up? Has anyone ever seen any SAE papers about how to properly design freeze plugs to prevent block cracking? If so, I'll be enlightened. It's possible that this all comes from back in the old tractor engine days.

I really think this is an automotive legend; a story that grew up out of nowhere and became Established Wisdom. But, it doesn't really matter.....

To me, "expansion" plugs are those aftermarket rubber plugs that expand when you tighten the stud in the middle. They're used for emergency/temporary replacement of blown out core plugs. All of the terminology gets mixed.

 

I think it's going to be like the "chicken or the egg" controversy
Here's a few things that I've been able to find:

"A Freeze plug is another name for core plug or expansion plug (commonly referred tto as a"frost plug.") Expansion plugs are a subset of the plugs on a car engine cylinder block or cylinder head. A usual plug is a thin, domed, disc of metal which fits into a machined hole in the casting and is normally put in by striking or pressing the center to expand the disc.

A real freeze plug is an expansion plug located in the side of an engine block that is supposed to protect the block against freeze damage. When Water freezes it expands, and if the coolant does not have enough antifreeze protection it can freeze and crack the engine block. The freeze plugs are supposed to pop out under pressure to relieve the pressure on the block.

On many engines the plugs could have been used where sand cores have been held. The sand cores are used in the casting process to form internal cavities in the engine block or cylinder head, for cooling water for example, and so should really be referred to as core plugs.

On some Freeze plugs a variety of block heater called a "freeze plug heater" can be installed, replacing the freeze plugs, to warm the engine before start up."

History of the Welch Plug

"Welch plugs get their "Freeze Plug" nickname because they are used so often to seal the holes left behind that are needed to extract the sand from engine block castings. This usually is a problem where the water jacket around the cylinders is formed. And when someone makes the mistake of using no antifreeze - or too little of it - those plugs will pop right out with the first cold snap."

 

KINDA hosin' you? Holy crap, the premix is only about a buck or two less per gallon than straight antifreeze. So you're paying for WATER at virtually the same rate as ANTIFREEZE. Talk about a hell of a profit margin on that stuff!

 

i would replace them with the brass ones.

 

I know that the Boss 302's and big Ford V-8's used screw-in plugs. I doubt that the plugs unscrewed themselves when the block froze. I vote with Xstrange: casting ports.

Semper Fi