Freeze Plug Repair?
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  1. #1
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    Default Freeze Plug Repair?

    Greetings!

    We have an older Clark Yardlift (gas) with a Continental flathead motor.

    It ran great until today a "plug" or something like it broke on the left-hand side of the engine resulting in a gush of engine oil.

    To me, this seems to be a cavity that would typically be sealed with a freeze plug, but what's in there now is something different. Perhaps a bad epoxy fix?

    Anyone have the ability to identify? We're in the early part of troubleshooting

    Thanks

    img_1892.jpg
    img_1893.jpg
    img_1899.jpg

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    Looks like failed epoxy glob repair to mysterious bullet-hole in valve cover of flathead engine.

    Remove cover, weld or bolt-plug hole, clean plate and mounting surface, replace with new gasket or sealing goop.

  3. #3
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    Kinda hard to tell what I'm looking at in those pics, freeze plugs are on water side of block, if oil dumped out it would be an oil galley plug, looks just like a freeze plug, but you know, its gotta have a different name. If its a nice round machined hole, measure and go to NAPA, if not nice round hole, idk, maybe some JB weld lol.

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    Pull the cover off. Fix the hole. Clean. New gasket. Put cover back on. Add oil to correct oil level. Use it.

    Love old engines.

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    valve lifter and adjustment cover. Remove and weld or goober it up again. Cork gasket will work best. Good time to check valve adjustment as they sometimes get tight and will float a valve. There may have been a vent tube there if the hole looks round and fabricated. If it has been working fine just plug it.

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    probably was a crankcase breather. It is common to have check valve breather on the valve cover. These allow pressure buildup in the crankcase to vent and then on the piston upstroke to draw a vacuum on the crankcase. Without this there will be a lot of piston blow by. Old engines simply exhausted the valve to atmosphere, modern ones into the intake manifold.

    I would not plug it as suggested.

    Tom

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    My old 1952 Yale has a breather tube in that location. Somebody must have "fixed" that one.

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    I also have an old forklift with a continental and mine has a breather tube here as well.

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    Its a breater,allright,and there may be a baffle inside the cover that filled with oil when the hole was blocked..........hence the oil leak will stop .On mine ,there is a bypass oil filter that returns via that hole,and any crankcase fumes come out the oil filler cap.............there will be no excess oil in the tappets,as there are drains down into the crankcase all along...(big enough to drop valve cotters in ,if you are not careful).........note the Continentals had a pin through the valve ,not two coned segments like a modern engine.

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    Yeah there should be a breather tube there. And a baffle that covers the hole inside.

    I don't think you can get that tappet cover off without removing the manifold, so I'd count on that. Is that a 4 or a 6 cylinder? I might have a spare for a 6 cylinder. Looks like a 4, but hard to tell.

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    yup should have a baffle with a Brillo pad like filter
    on the inside a pretty much all engines of that era had breather tubes
    about there and running down

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    Quote Originally Posted by dalmatiangirl61 View Post
    Kinda hard to tell what I'm looking at in those pics, freeze plugs are on water side of block, if oil dumped out it would be an oil galley plug, looks just like a freeze plug, but you know, its gotta have a different name. If its a nice round machined hole, measure and go to NAPA, if not nice round hole, idk, maybe some JB weld lol.
    The term “freeze plug” is kind on a misnomer also. They are really all just casting plugs. While on occasion, a “freeze plug” will blow when the water freezes and save the block or head, that isn’t it’s purpose. It’s main purpose is to get the sand out of the casting.

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    Actually, to be really technical, often the purpose of the hole is to provide a place to hold the sand core in the larger sand mold during the casting process. I think the actual name is a "welch plug", but I've always heard them referred to as "core plugs". That's my preferred term.

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  18. #14
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    I agree with the folks that think it is a breather. I shoulda thought more the first time.. so you might want to braze a tube onto it to allow directing the blowby...perhaps into intake/ You could add a PCV valve.

    I see two common types of casting hole-plugs. One is a shallow drawn cup...sometimes called a core-or cup-plug. The "welch" plug I think is a shallow dish which expands a little when the convex side is pressed on. IME the cup style is better. Seals better, less likely to fall out, more tolerant of hole size variation


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