OK, correct me if I'm wrong, but freeze plug holes in an engine block are a byproduct/necessity of the metal-molding process, right? And freeze plugs are just to fill in these holes..... Why are they called freeze plugs? Just curious. Thanks! Ben
Because if you do not have enough or any anti-freeze in your motor (Don't ask me why). They are designed to protect your motor. They are supposed to pop out of the block as the water feeezes and expands. Potentially avoiding a cracked block!
They are also known as expansion plugs. When water freezes it expands. The plugs will pop rather than crack the block. At least in theory.
I've also heard 'em called expansion plugs, core plugs or welch plugs. The idea of them protecting castings in freezing weather is more of a myth than reality. Their only real function is to ease the production of the casting.
At Chevrolet, the name of part number 838538 was "water jacket plug". That plug was used from the '30s thru the end of SBC I. The reason for a plug was there had to be a hole (or holes) for the core sand to fall thru after shakeout.
I think you'll find that the foundry supports the water jacket cores through those holes during the casting process. "Freeze plugs" is just another one of those obscure origin terms.
I'll vouch for their ability to pop out when water in the block freezes. My sister had an Olds that had straight water in it, popped out 3 plugs when it froze. They were a pain in the ass to put back in, but the block didn't seem to suffer any damage. Tim D.
Popped one out of my Toyota bombing down the highway in the summer.. You don't even know its overheating until the head warps and the motor quits. All the coolant drops out of the block and away from the sender. I hate those damn things. Shawn
frost plugs are where you put a frost plug heater ... used to keep your frost plugs from coming out when you don't have a frostplug heater...
A good friend had two rods in his old garage during one of our unusual deep freezes which lasted 3-4 days. About 2 days after the freeze we were messing around in the garage and noticed a run of antifreeze(green water really, obviously a poor mix) running from under one car. The T bucket backed in with the radiator near the leaky drafty door was just fine. The 36 Chevy pulled in nose first with the radiator against the workbench on the south side of the garage had the river running from it. We crawled underneath to find 1 plug on the driver's side pushed out and 2 on the passenger side. As the ice thawed the river had started flowing. We pulled the passenger side head and found no problems. We pulled the driver side head and found #5 with couple inches of green water in it and a split down the side of the cylinder wall about 3" long.
my take on it: when they cast the block, they need some support for the water jacket cores, and these supports leave some large holes in the sides and ends of the block. So, they bore the holes out to a standard size and put soft "core plugs" in them. But when you don't keep after your anti-freeze, and it gets cold out, the expanding coolant pushes the plugs out as it freezes. So, they get noticed when they pop out when engine freezes....and motorists naturally started calling them freeze plugs. They are not there to protect the engine from damage when it freezes, they are there to allow the engine block to be cast.
Soft plugs, made of a thinner metal than cast iron, the name that is universally used back here are supposed to pop if the coolant freezes and expands. Guess what...they don't work 99 times out of 100. I don't want to think about how many SBC's soft plugsplugs I've replaced behind the side mounts only to find a crack in the block around the plug hole after I changed them.. Jan
In my limited experience, I have yet to see evidence on a cracked block that cracked from freezing where the freeze plug ALSO "popped out" or even was slightly dis-lodged; hence, doing it's supposed job. Usually the block does. Futhermore, I have yet to see a block that froze, and popped out it's "freeze plugs". Is it just me?? Normally what happens is that you have an older car, the freeze plugs rust out, and then spew coolant everywhere. To top that off, the middle one is usually not accessible unless you pull the engine (on Ford and Chevy V-8's) at least...Depending on chassis. I should say that I have no doubt that they COULD work in theory...but, that seems to be the minority. Just my .02-
When water crystallizes and starts forming ice it expands in all directions. "Freeze plugs" have absolutely no effect on saving a block.....if the block didn't crack when the water froze inside, it was mostly luck and little else that saved it. "Freeze Plugs" get pushed out because they tend to move easier than the iron block material when pushed on from the inside......try it out on a junk block. Take a punch and hit the freeze plug. It'll rotate and pop out with much less force than the side of the block will cave in. -Bigchief.
they have saved my ass before! and they have caused me a lot of hassle too. nothing worse than one on a small block chevy between the block and transmission that is leaking making you have to drop the trans too fix it.
to those that dont think they pop out when a motor freezes... my car did exactly that one winter in the high country..went to start it and it wouldnt..looked under the motor and there were four freeze plugs on the ground.popped right out.i managed to thaw it out and put them back in, turned out the alloy head had cracked too, but did another 10,000 ks before i found that out..
don't count on that..... squirrel is correct, they are sand cast holes, nothing more.. if they pop out from freezing and the block ain't hurt, you got lucky...
An accepted colloquialism similar to nailhead or stovebolt. None are correct but everybody knows what you are talking about.
Many, many years ago, I had a Mk1 Ford Cortina that I somehow got to start in way below freezing weather. As I left the driveway I noticed some large coin like objects laying on the ground. I thought nothing of it until I noticed the needle on my temp gauge peaking about a mile later. I was young and stupid, I didn't realize that those things on the ground were freeze plugs. They actually did prevent the block from cracking but it's not something I'd like to test again.
I don't get why they have to be either core support holes or freeze plug holes. Perhaps they are both; first one, then the other! Freeze plugs saved my block from cracking: Drained the water (drag rules) from my BBC in the autumn. In the springtime I found a plug under the car that had been pushed out over the winter (unheated garage). Yes I do consider that lucky, too. I use the brass plugs. Incidentally, ice is a compliant solid, it does flow, so your blocks are not automatically doomed. Glaciers are ice, yet they flow.
Most think they are there to prevent cracks in the engine when the water freezes. Sometimes you get lucky, most of the time not. This is where the foundries wash out the sand from the sand casting used to cast the block. Ive seen some engines like the early Boss 302 with cast iron plugs screwed in this holes at the factory. They got the name way back because feeezing water will push them out...sometimes. So what does a cresent wrench look like. Does cresent only make one kind of wrench? Try open end adjustable. Does anyone have any water pump plyers? Do water pumps require plyers nowadays? Are floor boards made out of wood? Not since the horse and buggy days.
I can't tell you what I call them because this is a family show! I hate it when I look up at the truck above me and see them seeping. Usually means my day is gonna suck!
You (she) was lucky. The holes they "plug" are normally intended to release the core sand after the block has been cast. (keeps the water in) But every once and a while they WILL pop out when the water in the cooling jackets freezes. (must of only dropped a couple of degrees below freezing when hers "popped") IF, there is BIG drop in temp; they are just "extra pieces" left over!!
They are actually core support holes used to hold the water jacket cores centered in the proper position. You can't cast an entirelly closed chamber. They also provide another set of holes to get the burnt out core sand out of the chamber after casting the block but the main purpose is holding the cores. Now in most of the foundries the block patterns are styrofoam, whole block weighs about 3 pounds , if that. I seen em , been working in different foundry hell holes for 43 years.
Glaciers are ice, yet they flow. [/QUOTE] Actually they float on melted runoff. Kinda like an upside down freeze plug in the mess under the motor<!-- / message -->
Highlander, I have always respected your opinions on the board (and frequently agree with them), and I see the smile emoticon, AND I know this is not an earth science discussion, but my point is ice CAN flow (glaciers' movement IS primarily plastic deformation). Wait, were you just trying to goad me into a respon...oh crap. Not too defensive, am I? (multiple smile emoticons)
Freeze plugs aren't for protection against freezing?! You guys are nuts! I had my '69 Buick 225 V6 freeze because I was running pure water. I started it up one cold morning and the water pump would not turn because it froze! The freeze plugs had popped and help saved the block. My dad's 352 ford popped freeze plugs also. I would guess that if they are not there to be "pushed" out by expanding water then they wouldn't be pressed in. They would be threaded like all of the other block plugs that are used for manufacturing. But what do I know...... Mike
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