Where is the engine block coolant drain plug??? - Page 2 - JeepForum.com

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post #16 of 23 Old 10-21-2012, 11:20 AM
dproctor0715
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Quote:
Originally Posted by 5-90 View Post
Early ones took an 8m/m square drive pawl - this can be made easily from an 8m/m or 5/16" hex key with a grinder in about five minutes (grinding wheel in a drill motor/drill press, angle grinder, bench wheel, whatever.) You just grind down two opposite corners until it fits in the square.

I did the same thing to make the drain/fill plug wrench for my BA-10 transmissions (damned things!) It's easier to grind down a hex key than to grind down two faces on a 3/8" square.

I have unconfirmed information that it's a standard pipe plug - if it is, please let me know! I'd prefer to use brass there instead of steel (or maybe just put in a drain valve instead of a plug, so I can drain the block easily.)
Your ideas above make sense. I didn't know the correct size for the square key before I started. I was trying to find the correct size on JF when I found this thread. It didn't say what the correct size was at that time. I figured it was around 5/16" based the fact that the square end on my 1/4" drift punch fit loosely. I probably could have just put an adjustabe open end on that and turned the plug out, but feared the worst. So I didn't do it. Plus I wanted some information. So, after driving to two parts stores and asking for square key drivers, neither had them. I drove to ACE and bought a Craftsman 1" long 3/8 extension ($3.98) to size a tool out of. I knew it wouldn't twist off in the hole unless I ruined the steel by getting it too hot. I used what I had available in the shop. What I did worked. That's a fact. So I posted something here when I was done, for the next guy. - I ramble...

Anyway, after removing the plug I took it to the NAPA store where we verified it is a 3/8" NPT thread into the block. I then used a 3/8" X 1/4" NPT Brass Bushing so I'd have a hex head brass fitting tightened into the block to start with. Then the 1/4" NPT drain petcock threads into the bushing.

It's not leaking so far.
So if NPT isn't the right thread, someone please tell me what it is and I'll spend more money.

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post #17 of 23 Old 09-26-2013, 11:00 PM
predawn
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dproctor, i just did this and can confirm you are probably right on the size. 3/8th MIP bushing threaded in good for me to drain, but i have yet to find a hex head one to close it off for good (no desire to make a petcock).


ONE question: did you use any sealer on the brass threads? Is it necessary (like permatex #2?)
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post #18 of 23 Old 09-27-2013, 04:49 AM
5-90
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dproctor, i just did this and can confirm you are probably right on the size. 3/8th MIP bushing threaded in good for me to drain, but i have yet to find a hex head one to close it off for good (no desire to make a petcock).


ONE question: did you use any sealer on the brass threads? Is it necessary (like permatex #2?)
PTFE pipe dope or RTV won't go amiss, here.

And, thanks for the verification on the size. I now need to find a cable-operated 3/8" NPT drain valve...

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post #19 of 23 Old 09-27-2013, 06:14 AM
Paradise XJ
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Pulling the lower radiator hose should be just as effective.
The block drain is not an easy thing to get to...or remove. It's not a hex head, nor an allen, nor a torx. It's a 5/16" SQUARE plug. Since there is no readily available square wrench socket. You have 2 options.

Use a 3/8 ratchet extension (that you don't need) and grind all four sides down to make it 5/16 til it fits, then remove the plug and when you're done replace it with a regular hex head plug...

OR

#@&! IT...just pull the lower hose, there will still be about 1-2 cups of coolant in the block, then stick a garden hose in the lower part of the water pump to get MOST of any sediment out...MUCH easier and almost as effective.

...and when you ask "why'd they do that"? Because it was easier for them

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post #20 of 23 Old 09-27-2013, 06:32 AM
cory4um
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Or
If you wanted to go thru the hassel and a few $$

http://www.harborfreight.com/12-piec...set-94961.html
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post #21 of 23 Old 09-28-2013, 10:00 AM
predawn
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Or

http://www.pepboys.com/product/details/293916/00262/

If your not near HFT and/or need one in a pinch without buying whole set. 8mm fit my 97, i think its different for later year 4.0 blocks.
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post #22 of 23 Old 09-28-2013, 12:46 PM
89GerberXJ
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My coolant drain plug is on the drivers side of the block just above the engine mount. My '89 has a temp sensor in it but the junkyard motor had the goofy square hole plug. Since I reused the sensor I just use a bolt extractor to get it out.
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post #23 of 23 Old 12-31-2015, 11:38 AM
psyborgg
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Drain plug

I used a piece of 5/16 key stock from the hardware store. What got was a 12 in bar to give some leverage and used vise grips. If you use a wrench, they tend to be small and a cheater might break it. I also used a lot of penetrating fluid and waited a while.

Last edited by psyborgg; 01-05-2016 at 07:51 PM.
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