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Old 12-11-2010, 06:11 AM   #1
fryeguy2
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Trying to find out size of engine coolant drain plug

Iv'e been searching and for some reason can't find a site that tells me what size and type of thread the damn coolant drain plugs are on the bottom of my block. I have a 71 small block and I want to get a fitting to plumb a block heater into the engine.

If someone can help out i'd appreciate it
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Old 12-11-2010, 10:00 AM   #2
geezer#99
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Re: Trying to find out size of engine coolant drain plug

I assume you want to use a circulating block heater. Not a good idea to tie one in down there. Use one that fits in a freeze plug. JMHO
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Old 12-11-2010, 10:04 AM   #3
OhioDan
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Thumbs up Re: Trying to find out size of engine coolant drain plug

It gets cold enough in California for a block heater? Haven't seen one for the drain plug. The only ones I've ever seen went into a freeze plug hole.
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Old 12-12-2010, 10:54 AM   #4
RustyParts
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Re: Trying to find out size of engine coolant drain plug

1/4" Pipe thread.
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Old 12-12-2010, 03:20 PM   #5
Meatman
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Re: Trying to find out size of engine coolant drain plug

Quote:
Originally Posted by RustyParts View Post
1/4" Pipe thread.
Yep!
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Old 12-13-2010, 02:56 PM   #6
raycow
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Re: Trying to find out size of engine coolant drain plug

Is the heater going directly into the block or is it an external tank type? The tank type is normally connected to the heater hoses. 1/4" pipe is correct though, if that's where you need to go.

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Old 12-13-2010, 04:43 PM   #7
fryeguy2
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Re: Trying to find out size of engine coolant drain plug

Yeah, its the external tank type. I was going to plumb it into the block drain then have it head up through the heater core and back into the block. Would cutting the lower heater core hose and plumbing it straight in work as well?

No it doesn't really get cold enough here in CA to need a block heater, but I am wanting to install one to decrease engine wear on cold startups, be able to defrost my windows without idling the truck for ten minutes, and I have pretty high oil pressure when starting cold so I would like to mininmize that.
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