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Leaky Freeze Plug

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Let’s get real here. Why even bring a freeze plug with you as a spare? They are readily available at any parts house. If you have the freeze plugs with you, how many people have the tools with them to change the plug on the side of the road? Do you also bring two gallons of water antifreeze mix?

The answer to all of the above is no. A good preventative maintenance plan is all you need.
 
[ QUOTE ]
Let’s get real here. Why even bring a freeze plug with you as a spare? They are readily available at any parts house. If you have the freeze plugs with you, how many people have the tools with them to change the plug on the side of the road? Do you also bring two gallons of water antifreeze mix?


The answer to all of the above is no. A good preventative maintenance plan is all you need.

[/ QUOTE ]

Nope! You failed the course the plugs are designed to pop out in the event a system failure over pressurises the block. Happens when one is out on the road, have seen it happen wid me own eyes. OH! if you do not carry tools you be absolutely silly!.---Fwiw---Keoke /ubbthreads/images/graemlins/grin.gif
 
No Keoke, you failed to course. Freeze plugs were designed so that if you have water only or overly diluted coolant in cold climates and the water / coolant freezes and expands the freeze plugs are supposed to prevent the block or head from cracking. The freeze plugs will in theory will push out as the water freezes and expands. I have logged many thousands of miles in various models of British cars and I had to be towed only once a little over 35 years ago. I was street racing an MGA with a ’67 Sprite and power shifted into 2nd gear and the center of the clutch let go. As previously stated and I firmly believe, preventative maintenance is the key. If everyone would bring along with them all spare parts suggested we would need to install trailer hitches and pull small trailers. Or, if you loaded the boot you would really have a tail dragger.
 
My 56 Jag had a freeze plug go in spring in Oceanside CA at 11:00 at night. I thought it was the water pump at first. During the engine rebuild (two years earlier) it was over looked becouse they all looked good visually from the out side. The plug was removed by hammering a screw-driver through it and prying it out. A service station guy went home and brought me the Dorman and I was good to go(sort of). Who knew what evil lerks with-in. The loss of coolant caused an over heating enough to require a re-bore of one cylinder.
 
Although folks commonly call these things "freeze" plugs, they are in reality "core" plugs. Their real purpose is to allow for removal of the core casting sand. When a block is cast, a hardened sand mold is created to match the contours of the desired block shape, internal passages, & dimensions. Molten metal is poured into this mold & allowed to cool.

The temporary/expendable sand mold is broken off the completed casting. There is still sand in the now inacessible internal water jacket cavities which is removed through the previously molded core holes. After these rough access holes are further machined, cheap "tin" core plugs are inserted.

Some newer casting technologies use different methods but the older method was sand casting.

Since these plugs are the weakest part of the block, they "sometimes" pop out if water in the block freezes. Thus they often get the name "freeze plugs". This was never the intent of the plugs & they often don't protect the block from cracking if water does freeze in it.

I doubt if the plugs are really designed to pop out from system over pressure. The "pop out" just can't be controlled that accurately. More likely that a hose or a radiator tank will burst.

To prevent these cheap "tin" plugs from popping out at the wrong time, competition engines sometimes use screwed down bridge straps to retain the plugs. Others tap the core holes & use screw in plugs.

Since the thin, cheap metal plugs are subject to rust/corrosion damage they are often the first thing to fail on a higher mileage engine. Attached is a pic of a failed plug. There is rust scale on it , a hole to the right that was drilled to facilitate removal of the plug via sheetmetal screw, & a tiny but deep hole slightly to the left that corroded all the way through & caused a leak. In this case, it appears that the hole may have started from a tiny flaw in the plugs galvanized surface.

As you know, they sometimes just pop out as they weaken from corrosion damage, or other problems.
D
 

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Yeah Dave, They got the name "Freeze Plugs" because they are suppose to pop out if water freezes in the block as Big 6 Says. However, I have no experience with them performing that function satisfactorily. Similarly, I fail to see how a very thin plug due to corrosion which is not leaking can be diagnosed with Preventative maintenance and it will blow on the road if pressure is built up in the block.---Keoke
 
OH My Goodness Yes!! Preventative Maintenance is a good thing. Just make sure you have some tools and spares in the boot.This applies to those of us unlike Norman Knock and others that are fortunate enough to have a small caravan they tow.

.---Keoke- /ubbthreads/images/graemlins/rolleyes.gif
 
As Dave says, 'core' plugs are for removing the sand out of the casting. If a block freezes they may just pop out before the block cracks. Not a good idea to put this to the test though.

If the leaky core plug is a nuisance, why not use a little 'radweld' or the like?
 
/ubbthreads/images/graemlins/shocked.gif

WOT!! I thought they were "Welch Plugs" over in that part of the world, en I just wonder how they got that name ?---Keoke--- /ubbthreads/images/graemlins/laugh.gif
 
If you're going to nit pick, the Welch plug is flatter & requires a machined counter bore to seat into. The cupped plug as you know, is deeper, & does not require a counter bore, just a deeper bored hole. The cupped plug can withstand higher pressures than thw Welch plug. Technically the later Healeys used cup plugs, the early ones used Welch plugs.
D /ubbthreads/images/graemlins/devilgrin.gif
 
Hey Guys, Thanks for all the input on Core plugs! I was messing around with the weepy plug thing today, trying to clean it for a temporary fill of Marine Tex. My fingernail upset it enough, so now it's leaking a good bit. Guess I'll try to get the old rusty plug out and get something in there to measure the hole with. Might order one of Dave's suggestions. Gotta love this forum!!!
 
OH I know all about them things, But they still call all of them "Welch Plugs" across the pond Dave.---Keoke- /ubbthreads/images/graemlins/cowboy.gif
 
Bet you didn't know this. /ubbthreads/images/graemlins/wink.gif
The Welch plug may be so called in the UK but, it originated in the States & was patented in 1913 in the USA.
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Quote:

A brief bit of totally obscure history that I am one of the few living persons who knows.

My family business, established in Pontiac, Michigan in 1905, is the original manufacturer of the "Welch" plug. The Welch brothers had a motor car company at the turn of the century that was later bought by General Motors - the Welch Motor Car company. They would run the cars around Pontiac to "break them in."

At that time core holes in the engine blocks were fitted with pipe plugs. During one of these run-ins a pipe plug backed out. In order to get back on the road one of the brothers drove a quarter or half dollar into the hole. From this they developed the Welch plug, some with the help of my Great Grandfather Martin Hubbard. They then patented the plug and the M.D. Hubbard Spring Company become the sole manufacturer of the Welch plug for the life of the patent. To this day we have the largest range of sizes available anywhere.

So the Welch plug in origin is an American innovation and name.

Best Regards,

Nevin Hubbard
M.D. Hubbard Spring Company
www.hubbardspring.com
----------------------------
D
 
Naw didn't know about them things but I be willing to bet he stole it from a Pilgrim.---Keoke- /ubbthreads/images/graemlins/grin.gif
 
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