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dyeager535

dyeager535

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What the heck size wrench can you use to pull the oil galley plug out of the front of the block?? (the one that is above and behind the water pump on some blocks...male square drive)

I tried 1/4, 9/32, 11/32, 3/8, and the crescent to finish rounding it off, but none of them fit. I know the threads are 1/8", but I figured the head would have been 1/4"!
 
12 point 3/8" or 7/16" socket IIRC. Be careful using 12 pt. sockets as they can slip and round off the square head too! 12 pt sockets fit any square fitting but if you have rounded it off already....good luck. Oh, soak it with penetrating oil. Once you do get it out, put it back in with anti-seize on the threads.
 
I tried all those sizes with wrench and sockets. (just to make sure tolerances weren't bad on the wrenches)

The 3/8" was WAY too big, even putting a side load on it I couldn't get any grip.

These were on junk motors in the wrecking yard, I'm not too concerned with destroying an already garbage motor, so thats not an issue. I just got frustrated when all the tools I had wouldn't fit. Didn't have any metric wrenches or 12 points to try, but these were '70's motors, sure shouldn't be metric.

I'll probably end up buying some at Napa or something. I was at the wrecking yard for some other stuff, but of course, saw the plugs and had to try.
 
1/4" square is what they are supposed to be. You are correct about them being 1/8" pipe in the block. Whya rae you trying to remove it? Also I am pretty sure that GM stopped using them in the front of the blocks by 1969.
 
im trying to figure out why you would use a box end wrench to try and remove a square plug, myself.. just use the open and of the correct size wrench, 1/4 or 3/8...
 
dont bother using the stock plugs like that, just go buy some pipe plugs, with a reset hex head much easier and less chance of rounding off.
 
I don't think GM ever did stop using them on the blocks we deal with. Supposedly an indicator of 4 bolt main blocks (I have my doubts, but haven't disproven that theory so far) but in any case, I've seen them on plenty of motors, to include the one that came out of my dads '74. (not going to state it was original to the truck though, because I don't know for sure)

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Why are you trying to remove it?

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I just need three more. My SDPC EGR feed pipe (setup for TPI Vortec headed engines) has a threaded hole for a late model EGR temp sensor, and the intake base itself has a tapped hole in the back that goes into the coolant passage. Had to use the one on the front of the block to put in the rear of the block, since the intake base made that port unusable, so now I need one for the front. Of course, no clue how I got the original one off, didn't think I'd ever have to deal with it again. /forums/images/graemlins/smile.gif Besides, I was at the wrecking yard anyways, why not do all my shopping on one trip if possible?

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im trying to figure out why you would use a box end wrench to try and remove a square plug, myself.. just use the open and of the correct size wrench, 1/4 or 3/8

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Because an open end wrench will never be as strong as a box end. Case in point, I tried it with a 5/16 which was just a tad bit too big for these plugs. Open end wrenches can't be used with a lot of force, since nothing holds the open ends in place. It just opens up. Pretty much the same reason crescent wrenches aren't good for tight stuff usually. IN any case, none of my box/open end wrenches fit correctly anyways. My giant crescent wrench only succeeded in finishing off any semblance of flats on the plug.

I'll just go and get new plugs. Gotta go to Napa anyways. /forums/images/graemlins/rolleyes.gif

Had I more time, I would have checked other motors for wrench fitment.
 
The correct tool for a square head is an 8-point socket. They're made specifically for square head bolts, nuts, etc. /forums/images/graemlins/cool.gif Sears sells 'em.
 
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Because an open end wrench will never be as strong as a box end. Case in point, I tried it with a 5/16 which was just a tad bit too big for these plugs.

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Break into your piggy bank and spring for some Snap-on Flank drive open end wrenches. They work very nicely
 
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Also I am pretty sure that GM stopped using them in the front of the blocks by 1969.

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My factory '71 350 4-bolt main block has that plug. /forums/images/graemlins/thinking.gif
 
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Break into your piggy bank and spring for some Snap-on Flank drive open end wrenches. They work very nicely

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More like smash your piggy bank! I know snap on tools are nice, but its absolutely insane what they charge for that stuff. I don't think that even if i was 60 years old and had a good job I could afford a complete set.
 
hehe, whats a complete set? /forums/images/graemlins/wink.gif

i've got about 50 grand in Snap On chit and i still find stuff i need..

they've got this sweet new boroscope i could really use for work, but 400 clams isn't in the budget at the moment. tough being a tool addict.

i've found their are certain things as a fulltime mechanic that you really need Snap On, alot of other lesser used tools i'll get away with something cheaper.. but wrenchs, screwdrivers, ratchets and others don't survive the day in, day out torture unless they are highend tools.. got tired of returning exploded 3/8's ratchets to Sears.....

if ya ever want Snap On stuff, Ebay generally runs at about 1/2 price compared to the truck on alot of items. just gotta know your prices...
 
Snap on has a special set of sockets JUST for the core plugs like this. But the problem for me has always been that they are in so tight that the top twists off anyways! I usually end up drilling it out, heating the block up with torches and removing it with an easy out.

Those plugs were used on the heavy duty blocks. and were used all the way up to 86 from what i have seen. They were an indicater that it "could" be a 4 bolt, but not all the casting were made into 4 bolts. just the heavier casting. Known in the past as the "power plug", but all it means is the block has a higher nickle content. but stronger than a normal 2 bolt.
 
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Known in the past as the "power plug", but all it means is the block has a higher nickle content. but stronger than a normal 2 bolt.

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Not to be a thorn in your helpful side, just going to mention that this is probably like those 010/020 block theories, since I've already heard they meant 4 bolt mains exclusively and you mention another theory. No reason for GM to spend the extra $$ to drill an oil galley plug just because the block is stronger or has 4 bolt mains.

Only reason I can possibly think of that GM would have needed to externally ID either 4 bolt or "stronger" block castings would have been for warranty replacement. In either case, a cast or stamped in ID number (suffix code too) would have been ten times easier and cheaper, unless the same molds were used for all blocks.
 
as far as i know its simply a capped off oil feed and iver seen all kinds of engines with this plug there, right now i have a 73 350 and 83 350 with such plug in it and the 83 305 doesnt, the 73 350 is just 010 and no 020 and is 4 bolt, but the 83 i dont know, its in the truck haha, the 73 one is 155hp, thats not very much, and we know an 83 M-code HD truck 350 engine is no HP mnosnter either, so id have to say it has nothing to do with power haha



no clue what size it is though, but hot melted candle wax dripepd into around the threads would have helped you get it broken loose.


good luck.
 
The plug in the front of the engine above and to the passenger side of the timing cover was for a oil pressure switch on early year engines. They were most common on 265, 283, 302, 307, 327 enignes up til the late 60's some into the early seventies maybe. I have never seen any on anything later than 1969 though.
 
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no clue what size it is though, but hot melted candle wax dripepd into around the threads would have helped you get it broken loose.

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Close. Heat the plug with a torch. Melt some paraffin wax into the threads with the hot plug.
 
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Close. Heat the plug with a torch. Melt some paraffin wax into the threads with the hot plug.

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So hows that work? Heating the plug will expand the threads, meaning the grip will be tighter than it was before. (while it is hot)

More than likely, if the paraffin trick ever did work, it was because the heat broke the bond of the metal, not because of the paraffin. Same reason extreme heat by itself works on the exhaust manifold studs.

Of course, heating/expanding the surrounding metal makes more sense, since the plug would tend to be slightly cooler, thus less thread contact as the base material expands.
 
The heat works by expanding, then contracting, the threaded object, which breaks loose the rust holding the threads together (usually). A <font color="red"> small </font> amount of the paraffin wax will be drawn into the threads as the area cools, and will act as a lubricant, but the heating/cooling cycle is what really does the trick.
 
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