Popped a freeze plug

[DirtDonk]

Thermostats don’t ever act as a restrictor?
Wouldn’t that naturally increase pressure behind it slightly?

 

[ba123]

It’s the cap that would set the max pressure. The cap or the weakness that won’t hold as much as the cap.

 

[DirtDonk]

The cap isn’t more responsible for “ambient“ pressure? Whereas the thermostat/restrictor would be contributing to actual “water pressure“ between it and the pump. Unless that’s not a thing.

 

[ba123]

No, ambient pressure is irrelevant in a closed cooling system. That affects the air density in the intake. In a cooling system pressure is built up from thermal expansion and then limited by the cap. If you have a 14lb cap, your system will build pressure to that amount and then release anything over it.

Happy to have someone tell me I’m all wrong so I can question life as I know it though.

 

[DirtDonk]

Pressure that increases by heat is what I’m calling ambient.
Not outside air pressure. Whatever it’s called when pressure is built up from heat.
You’re calling a thermal expansion, but is there another term for it? Is “ambient” not appropriate?

I could be wrong too, of course, but I was under the impression that “water pressure“ created by the pump impeller is an actual condition of the water movement through the system.

 

[Johnnyb]

Ford's are always straight.

I feel like I've made some progress on "starter relay".

Well, a proportioning valve IS a proportioning valve. It's just that Ford didn't put them on Broncos, ever. My '98 Taurus has one, but none of my trucks.

The thermostat has nothing to do with system pressure. Its only function is to reduce warm-up time so the PCV system works sooner; nothing else.

A 190 thermostat basically guarantees that the cooling system will exceed 212 which means that there is pressure in the cooling system. A 12lb. cap holds it in.

 

[Steve83]

Thermostats don’t ever act as a restrictor? Wouldn’t that naturally increase pressure behind it slightly?

Yes, but that only changes the head (flow-generated) pressure; the overall system pressure remains the same whether flowing or not. Yes, high flow from the pump pushing through the t'stat creates slightly-higher pressure in the block, which slightly-increases the coolant's boiling point around the cylinders & heads. That's why, when coolant is beginning to boil, turning the engine off (stopping the pump's flow, dropping that pressure down to the cap's rating) causes a violent blowout because the coolant in the engine flash-boils.

But none of that is the purpose of the t'stat. The engine would run the same at the same operating temperature without a t'stat. It would just take a little longer to reach operating temp.

...pressure is built up from thermal expansion...

That's not where the pressure comes from because the block, radiator, & even the hoses ALSO expand as temperature rises, making more room for the expanding coolant. It's when the coolant begins to evaporate more at the higher temp that the system pressure begins approaching the cap vent pressure.

A 190 thermostat basically guarantees that the cooling system will exceed 212...

No, it doesn't, because the t'stat is always there, but the temperature falls when the engine is off. So the t'stat has basically no effect on operating temperature. It's the gasoline burning around 3K°F that guarantees the operating temperature will rise. The t'stat only affects how FAST the temperature will rise when the engine is running. But once it opens, it has no more effect on the maximum temp that the engine will reach.

 

[DirtDonk]

Oh goody. We haven’t had a nice “Steve83“ argument in a long time! Kind of miss them…

 

[ba123]

Oh goody. We haven’t had a nice “Steve83“ argument in a long time! Kind of miss them…

I’ll pass. Signing off.

 

[73azbronco]

I coat them with RTV then tap into place until they are flush with the surface. Go too far and they drop into the cooling jacket and you need to fish them out with channel locks. Clean the bore really good in case there is something that caused it to come loose. Machine shops let the new guy install these so maybe it was just a bit cocked? Getting to that look terrible.

my machinist used that Indian shelac, it's not coming out or leaking unless it blows up.

 

[gnpenning]

Yeah, anyone saying it will run the same temp and just take longer to get there without a tsat, has never been in a cold weather state during the winter.

 

[Steve83]

Yeah, anyone saying it will run the same temp and just take longer to get there without a tsat, has never been in a cold weather state during the winter.

You're right - I was only thinking about warm & hot weather. In freezing weather, it might take longer than the gas tank lasts (like until Spring).

 

[Johnnyb]

Yes, but that only changes the head (flow-generated) pressure; the overall system pressure remains the same whether flowing or not. Yes, high flow from the pump pushing through the t'stat creates slightly-higher pressure in the block, which slightly-increases the coolant's boiling point around the cylinders & heads. That's why, when coolant is beginning to boil, turning the engine off (stopping the pump's flow, dropping that pressure down to the cap's rating) causes a violent blowout because the coolant in the engine flash-boils.

But none of that is the purpose of the t'stat. The engine would run the same at the same operating temperature without a t'stat. It would just take a little longer to reach operating temp.

That's not where the pressure comes from because the block, radiator, & even the hoses ALSO expand as temperature rises, making more room for the expanding coolant. It's when the coolant begins to evaporate more at the higher temp that the system pressure begins approaching the cap vent pressure.

No, it doesn't, because the t'stat is always there, but the temperature falls when the engine is off. So the t'stat has basically no effect on operating temperature. It's the gasoline burning around 3K°F that guarantees the operating temperature will rise. The t'stat only affects how FAST the temperature will rise when the engine is running. But once it opens, it has no more effect on the maximum temp that the engine will reach.

I humbly disagree. And we're not talking about radiator caps or thermostats; we're talking about freeze plugs. A 12# or 16# cap allows pressure to accumulate in the system, allowing the vehicle to operate at temperatures above the normal boiling point. This, in turn, places pressure on the "freeze plugs," which in my original statement, I said were disconcertingly easy to place - in my opinion necessitating the use of some form of glue to supplement the friction-fit. I am thinking I used Locktite 620.

-JB

 

[Steve83]

I humbly disagree. And we're not talking about radiator caps or thermostats...

Yes, that's what we (the people I quoted & I) were talking about in my post that you quoted. What I said to you is on the first page:

They're not freeze plugs because 1) you should never let the coolant freeze, and 2) the plugs aren't designed or intended to do anything differently if you make that mistake. They're just bore plugs (or core plugs) because they're only there to plug holes in the casting that were necessary to hold the sand during the pour, which were later bored smooth so the plug could fit & seal. Ford never leaves a stop lip because that would make it nearly impossible to remove one without damage to the block. I usually add some Hylomar Blue to the bore before driving the plug in, but in a block that had rusted due to rubber plugs leaking for years, I added JBWeld to a couple.

I suspect yours came out because it was undersized, or the bore was damaged, and it was only the silicone holding it in until now. If you clean the silicone off (a cup brush in a die grinder works well), does the plug fall into the bore?

 

[blade]

No, it doesn't, because the t'stat is always there, but the temperature falls when the engine is off. So the t'stat has basically no effect on operating temperature. It's the gasoline burning around 3K°F that guarantees the operating temperature will rise. The t'stat only affects how FAST the temperature will rise when the engine is running. But once it opens, it has no more effect on the maximum temp that the engine will reach.

The thermostat doesn't just open and stay open once engine temp is reached, it's controls the exchange of water between the radiator and the block. When the coolant reaches temp the tstat opens this sends the hot water to the radiator, the cooled water from the radiator goes into the block cooling it off and shutting the tstat until its opening temperature is reached again. In a hot environment no tstat or a broken one can result in overheating.

 

[Steve83]

In a hot environment no tstat or a broken one can result in overheating.

How do you imagine a t'stat normally works in a hot environment? And how do you imagine no t'stat in a hot environment could cause overheating that wouldn't happen if there were a t'stat?

How many t'stats have you ever seen or heard of breaking in a way that caused overheating? I think I might have heard of 1 (being generous) in 40+years. But none in the thousands of vehicles I've worked on, owned, or driven.

 

[Broncobowsher]

OK, I'll add to the party...

I typically set the depth of the core plugs below flush the same as the thickness of the plug. If the plug material is .020" thick, the square corner of the plug is .020" into the bore. Just use an eye-crometer to set that. I don't want to chance that the corner isn't in the bore. I use a sealer, but not RTV. I typically have an anarobic sealer on hand, or some Hylamar. Not opposed the formagasket. Not uncommon for the bores to be in less than perfect condition.

As for pressure and thermostats. Worst pressure is not at operating temperature. Closed (or mostly closed) thermostat and high RPM. Small block Fords have been known for half a century for there ability to blow up a heater core. I am guilty of making a few die when I made a hard pull on a bit too cold of an engine. Ford made restrictor kits to put in the heater lines of many vehicles (Police fox body mustangs are probably the most famous). That is why the heat shut off goes on the water line off the intake and not the water pump inlet. The shut off cuts the pressure going into the heater core but not limiting the water pump from pulling from the core.

And correct, they are not freeze plugs. They won't pop out to protect the block if it is full of water and freezes. They will pop out after the block cracks and relives the tension on the plugs because the bore is cracked open. Seen plenty of blocks that froze and split. You wouldn't think that most of those were in AZ and southern California. But people don't think about freezing in those areas and it does freeze here. Thus a lot of cracked blocks. Usually blows the water jacket to the outside, but it can blow the cylinder bore as well. That's fun, trying to get a piston out that the cylinder imploded.

 

[ba123]

Love the eye-crometer method. I'm pretty good at measuring with that tool as well.

 

[jamesroney]

OK, I'll add to the party...

I typically set the depth of the core plugs below flush the same as the thickness of the plug. If the plug material is .020" thick, the square corner of the plug is .020" into the bore. Just use an eye-crometer to set that. I don't want to chance that the corner isn't in the bore. I use a sealer, but not RTV. I typically have an anarobic sealer on hand, or some Hylamar. Not opposed the formagasket. Not uncommon for the bores to be in less than perfect condition.

As for pressure and thermostats. Worst pressure is not at operating temperature. Closed (or mostly closed) thermostat and high RPM. Small block Fords have been known for half a century for there ability to blow up a heater core. I am guilty of making a few die when I made a hard pull on a bit too cold of an engine. Ford made restrictor kits to put in the heater lines of many vehicles (Police fox body mustangs are probably the most famous). That is why the heat shut off goes on the water line off the intake and not the water pump inlet. The shut off cuts the pressure going into the heater core but not limiting the water pump from pulling from the core.

And correct, they are not freeze plugs. They won't pop out to protect the block if it is full of water and freezes. They will pop out after the block cracks and relives the tension on the plugs because the bore is cracked open. Seen plenty of blocks that froze and split. You wouldn't think that most of those were in AZ and southern California. But people don't think about freezing in those areas and it does freeze here. Thus a lot of cracked blocks. Usually blows the water jacket to the outside, but it can blow the cylinder bore as well. That's fun, trying to get a piston out that the cylinder imploded.

I tried so hard to stay out of this thread, but I just can't let this nonsense persist. So sit back, listen, and enjoy.

1. You cannot look backwards at an evolution and describe it using context from today. That is the wrong way to evaluate it. The proper way is to start at the beginning, and look FORWARDS. This is the same error that causes most religions and politics to go off the rails. Same is true for automotive evolution. So let's begin with the beginning.

In 1886, Karl Benz invented the liquid cooled internal combustion engine. It took another 8 years or so for Maybach (1890's) to put a radiator in front of it. Then it took another 20 years for Henry Ford to mass produce it into the model T. For 20 years, from 1908 to 1927, over 15 million units were made, and they did not have cup plugs. The first 4 years of production used threaded plugs in the block. Then in 1913, Allie Welch of Welch Motorcars was award US patent 1,058,210 for the expanding disc core plug. That core plug type was used by Ford motor company from 1913 to the late 1950's. The modern cup style core plug was not used in a Ford until the later Y block, and FE. Then of course in the Small Block Cleveland released in 1962. It is worth noting that the language evolved over time, but the nature of the convex Welsh plug, expanding when flattened also became known in the late 1920's as an expansion plug. Which makes perfect sense if you think about how it works. Take a round disc, peen it with a hammer to make a dome, insert the dome into a recess in the block. and smash it flat...and it expands. For 30 years the Welsh patent expanding disc core plug was THE method of sealing core plugs in cast iron engine blocks. At the same time, people in cold climates learned that if the weather was sufficiently cold, they could come to their car in the morning, and the ground would be covered with water, and and the Welsh Patent expanding disc core plug would be on the ground. There have been MANY instances where marginal slushy ice formation ejected the core plug before the block cracked, but in general, the appearance of a Welsh plug on the ground next to a puddle meant your engine FROZE. Many enthusiasts came to believe that the design intent of the core plug was to eject the plug before the block cracked. So the Welsh Brothers Patented expanding disc core plug became known as the "Freeze Plug" or a "Frost Plug." It is an ABSOLUTE indicator that your engine has experienced an ice event, and it is legitimately called a "freeze plug." If you don't like the name, then call it whatever you want. But if you want to call a Hooke's universal joint a "Cardan" joint, then you should absolutely call a Deep Draw cup plug a "Welsh Plug." (Even though it isn't...) The 1965 Ford FE 427 received threaded core plugs, and the Small Block Ford in 1969 Boss 302 received similar threaded core plugs. The Ford Motorsports 4 bolt main small block also received o-ringed threaded core plugs.

Fast forward to WW2, and the US Government needed a solution to water ingestion during amphibious operations in the M3A3 Stuart tank. Cadillac designed a "closed ventilation system" to eliminate the road draft tube, and applied that to the M5 Stuart in April, 1942. This was the first production PCV system. It had absolutely nothing to do with emissions, is not an emissions device, and was never intended as such. Nevertheless, it was applied to various automobiles thruout the 50s', and because mandatory in the 1960's. The first thermostat was installed by Cadillac in 1914, and became prevalent in the 1930's. The First pressure caps became popular in WW2, and in 1954, the 7lb Raymond Stant pressure cap was installed in the Kaiser-Frasier.

So all of the backwards looking "this happened because of that..." is just revisionist analysis looking the wrong way.

Freeze plugs indicate that a frost/freezing event has happened. They can and have popped out prior to blocks cracking in some rare instances. They are not designed to protect the block from a frost/freezing event.
Deep draw core plugs are called "freeze plugs" because people like to call them that.
Deep draw core plugs are called "expansion plugs" even though they don't expand.
Deep draw core plugs are called "Welsh plugs" even though they aren't.
Deep draw core plugs are never called "core plugs" even though that's what they are.

Now I forgot what I was trying to tell you. So I'll stop.

 

[ba123]

took you long enough!