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Block coolant plug broke off.... I'm screwed, huh?

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Block coolant plug broke off.... I'm screwed, huh?

Old 10-12-2018, 04:31 PM
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Default Block coolant plug broke off.... I'm screwed, huh?

I decided to remove the block coolant plugs using my big breaker bar last night. First one came out without a hitch (couldn't have done it without the breaker bar, though); the 2nd one FELT LIKE it was coming out just fine but only the bottom 2/3ds of the plug came out; the other 3rd is stuck in the block...

I've got basically zero hope of getting this out and should just put this on the machine shop's "ToDo" list, right?
(I'm going to be putting a knock sensor in the other side, so I'd like to have at least one coolant drain plug that works...)

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Old 10-12-2018, 04:48 PM
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Drill it out as much as possible without getting into threads. Use the largest EZ-OUT that will fit. Heat the area around it with a torch. Otherwise use a chisel/punch to bust it up.

Is it a brass or steel plug?

Heat is your friend when removing pipe plugs/fittings.


Last edited by 427Hotrod; 10-12-2018 at 04:48 PM.
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Old 10-12-2018, 05:27 PM
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I’m assuming you took out the drain plugs near the oil pan. If you got most of it out and the threads are still good in the beginning, just drill and chip it out with a dremel.
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Old 10-12-2018, 09:52 PM
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it should be a NPT pipe thread so if you do gouge it up it can be re tapped but NPT taps can be pricey. If its not leaking you could wait til its time to go to the shop. If done driving for the winter then I would start goiing at it myself. I would drill out the center, heat the crap out of it then stick and ez-out in it and see if it will move. Good luck, if its an iron plug its going to be a challenge.
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Old 10-13-2018, 03:00 AM
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Adam, your best bet is to drill out the center all the way through, then heat it up cherry red with an oxy-acetelyne torch and let it cool. You may be able to get it up to cherry red with a mapp gas torch. It has been my experience that the propane torch won't put out enough btu quick enough to get it that hot.
once it has cooled off, it will likely turn out pretty easy. For some reason, and I don't know the physics of it, when you drill all the way thru, it relaxes the tension of the threads, and when you heat it up, the rust seal is broken and and when it cools, the threads shrink. I've removed quite a few bolts and plugs that way.
If I remember correctly, didn't you pull the motor recently? If so, you shouldn't have too much issue removing the plug remnant.
Good luck.
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Old 10-13-2018, 06:26 AM
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Mr.Jeff has the process right. The only thing I would add is to squirt it with PB Blaster while it's still hot. Smokes a lot but always seems to work for me. Then work it back and forth if you can. Repeat if necessary. And you do need a torch other than propane. The mapp works great. Good luck.
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Old 10-13-2018, 07:09 AM
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Use the approach Jeff shared. You’re actually lucky as far as broken bits go, as it is the easiest to remove. The npt threads are tapered and should have thread sealant applied when they were originally installed. The heat will melt the sealant and it will act as a lubricant. Once you break it loose, each turn loosens the fitting given the tapered threads. Good luck!
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Old 10-13-2018, 07:40 AM
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You're not going to get it with an easy out. The easy out will break off and then you will really be screwed. If you broke off the plug head it's in too tight for an easy out to remove. Easy outs are very hard, not strong. You're going to have to drill it and either finesse the threads out or drill a bigger and put a larger pipe tap into it. Or any thread tap or (Bubba) an expanding rubber plug.and heating with a torch won't work unless you get all of the coolant out. Otherwise the coolant is just going to absorb the Heat.and coolant drain plugs aren't that crucial unless it's a raw water boat motor. The reason it broke off, it never got used.

Last edited by derekderek; 10-13-2018 at 07:42 AM.
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Old 10-13-2018, 07:46 AM
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As long as you're sending the block to the machinist for, well, machining, let them do it. They should have the right tools for the job and it'll be done right.

Everything is different when you have the right tools for the job.
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Old Yesterday, 06:29 PM
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If there's a hole in it maybe a small saw cut through till you are just shy of the threads and use a cold chisel to split it then collapse the side.i had one 2 guys did everything already described and I had it out in 20 min . Or wait for the machine shop.
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Old Yesterday, 06:43 PM
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For the hassle, tools and time it'll take you to fix it I wouldn't. Let the machine shop deal with it.
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