Oil Gallery Plug Historical "Data"? (1 Viewer)

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I was discussing the potential for oil gallery plug blow with a buddy (not a LC owner) who said that the only time he'd ever heard of an oil gallery plug blowing was during a deep freeze event. I'm wondering if anybody has enough depth of info on the history of these in Cruisers to know if there was something like a freeze that was common to them blowing.
 

OSS

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I replaced a friend’s leaking plug in 1988 in So Cal. He had an ‘86. Don’t know if he ever went up to the mountains to freezing temps.
It’s a plug to block off an oil passageway, not a coolant plug, so freezing temperatures shouldn’t matter with such a tiny plug.

My original plug never leaked in 30 years and 290K miles and the engine had been through hell & back uncountable times.
 
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My FJ60 had almost 400k on the original motor, the oil gallery plug was still intact and not leaking.
Just installed a rebuilt head as part of a freshen up job I've been doing, the original owner never really fixed or touched anything on the motor.
 
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I recall reading about this years ago and I might be conflating things or remembering wrong, but I think they’re installed to blow out if the engine block gets cold enough to freeze it will blow the oil out of the plug and release the pressure so the block doesn’t crack. But I never really understood the logic there... I’m not sure how cold you have to get to make oil freeze... I also recall reading about an arctic land cruiser model with some special extreme cold provisions such as a wind screen over the radiator to keep the engine from freezing while driving in sub zero temps.
 

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the oil pump has a preasure relief in it, it will/should only build a certain amount of preasure whether it is hot or cold.

I had a thread many years ago about a friend pulling into my driveway with a "new" 60 he just bought, opened the hood, looking things over and the oil galley plug was halfway out the head. Took a pair of needle nose pliers and pulled it out the rest of the way. He had no idea. He was lucky, we fixed it right in the driveway and off he went. It had pics in the thread.

I can't find the thread right now.
 
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I recall reading about this years ago and I might be conflating things or remembering wrong, but I think they’re installed to blow out if the engine block gets cold enough to freeze it will blow the oil out of the plug and release the pressure so the block doesn’t crack. But I never really understood the logic there... I’m not sure how cold you have to get to make oil freeze... I also recall reading about an arctic land cruiser model with some special extreme cold provisions such as a wind screen over the radiator to keep the engine from freezing while driving in sub zero temps.

apparently oil gets more dense as it gets colder--it does not expand (getting less dense) like water does when frozen. I don't think the galley plug is a "freeze plug". It's just there to plug a hole that had to be drilled through to the outside of the block.
 
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apparently oil gets more dense as it gets colder--it does not expand (getting less dense) like water does when frozen. I don't think the galley plug is a "freeze plug". It's just there to plug a hole that had to be drilled through to the outside of the block.
Yeah reading more on it this afternoon. Oil never crystallizes but will become like a tub of grease in temps -40 or below. That plug is there from a necessary machining process to open an oil passage after the casting is done. Toyota likely used the non threaded plug because it was way faster than tapping it for threads at the factory. Makes me wonder if you could weld it shut during a rebuild and never have to worry about it again. I suppose you risk welding your oil passage closed too though. I’ve never seen the other side or hole and where it leads so I’m not sure. Tapping it for a threaded plug is simple enough though.
 

ChaserFJ60

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As mentioned before, this oil galley plug needed to be drilled out for an oil passage in the head. Mine didn't fail until after I rebuilt my engine and had the head and block dialed in at a machine shop. Im not sure which cleaning methods they used on my engine but many of them can cause the galley plug to "break loose."

Some cleaning methods used in an engine refresh that im aware of (I may be wrong I don't work in a machine shop.)
Baking - where they heat up the components to ~600F.
The Spray cabinet or a parts dishwasher where the machine shop may or may not use a "Caustic" cleaning solution. Caustic in this case means safe to clean our iron blocks with, but bad for aluminum.

If the shop doesn't notice the aluminum plug and puts it in a caustic mix it can ruin the plug, or when the head gets baked in an oven the aluminum plug and the cast iron head will have different rates of thermal expansion causing them to "break loose" under a high temperature change.

If you have the time its a good idea to go ahead and put a threaded plug in IMO.
 
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As mentioned before, this oil galley plug needed to be drilled out for an oil passage in the head. Mine didn't fail until after I rebuilt my engine and had the head and block dialed in at a machine shop. Im not sure which cleaning methods they used on my engine but many of them can cause the galley plug to "break loose."

Some cleaning methods used in an engine refresh that im aware of (I may be wrong I don't work in a machine shop.)
Baking - where they heat up the components to ~600F.
The Spray cabinet or a parts dishwasher where the machine shop may or may not use a "Caustic" cleaning solution. Caustic in this case means safe to clean our iron blocks with, but bad for aluminum.

If the shop doesn't notice the aluminum plug and puts it in a caustic mix it can ruin the plug, or when the head gets baked in an oven the aluminum plug and the cast iron head will have different rates of thermal expansion causing them to "break loose" under a high temperature change.

If you have the time its a good idea to go ahead and put a threaded plug in IMO.
Apparently there’s a galley plug on either a Chevy or ford engine that is called the forgotten plug. It is often knocked free during the cleaning process of a rebuild and if it goes unnoticed you might assemble the entire engine and have zero oil pressure. It’s not just a land cruiser thing.
 
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I thank my lucky stars that mine was done by the previous owner. And I don’t have many lucky stars... 🤣
 
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It's just so bloody difficult to get to unless the engine is pulled.

Its a pain, Ive done two while the head was still in the engine. Getting to it is the easy part, its stopping the metal shavings from falling inside the engine that's hard. :grinpimp:


I don't find it that hard to do them in the engine bay. usually can be done in under an hour.
 

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