Bottom drain plug on M carb won't budge

Patrick HMD · Jul 17, 2012

It's kicking my --- big time! Apparently the prior owner had the same problem because the square head was already rounded off, probably with a pair of vice grips. I just made it worse by trying the same thing.

Can I assume that it's an 1/8" NPT pipe plug? If so, not hard to replace.

I've got it soaking with some PB on the inside for now. I can only think of three options to try. First, heat plug a good cherry red, then try to wiggle it free with vise grips. I did remove the fuel adjusting screw, packing nut, and packing to avoid damage from the heat. Second, drill hole in middle and try backing it out with an easy out. Third, just leave it alone and not worry about it.

It's just a minor detail, but sometimes those minor details really eat on me.

I'm sure others here have had the same problem. Any other suggestions?

TIA, Patrick

Phil Tibbetts · Jul 17, 2012

If the bowl is pot metal be careful with the heat. Just warm it up a little very slowly. When it starts to melt it may end up in a big blob. The pot metal should expand faster than a steel plug and allow you to get the plug out.

Patrick HMD · Jul 17, 2012

It's cast iron Phil, magnet stuck right on.

Thanks.

TJV · Jul 17, 2012

in my expirence in heating things up once you have heated and cooled they seem to get harder and your other option of drilling it for an easy out will be more difficult and could end up breaking or dulling a drill bit very easy.

randy hall · Jul 17, 2012

the plug is cast iron too. not much chance of it getting hasd with a little heat.

Phil Tibbetts · Jul 17, 2012

Heat may still help. Heating will not harden it unless you cool it suddenly. I am a retired machinist and have removed hundreds of rusted and frozen bolts and pipe fittings over the years. Just take your time and if you decide to drill it out start with a small drill and slowly work up. Be careful not to get into the threads on the bowl. When you get to 1/4 or 9/32 heat the pipe plug inside the hole you drilled to light red, then let it fully cool and you can probably turn the plug right out. Hope this helps. I didn't realize that you had a cast iron bowl before.

teddy52food · Jul 17, 2012

Don't even think of using an easy-out. Weld a nut on that rounded square shank & let it cool some & turn it out.

Patrick HMD · Jul 18, 2012

I"m going with Phil's method. Sounds very logical, and I'm confident that it will work for me. Makes me feel more at ease now that I see a way out. I've used the welded on nut method before with good results. But not anything this small. Don't think my 72 year old eyes could handle it. My hand's not that steady either anymore. Getting old is such a drag. Don't have a mig, just a Hobart gas stick.

Thanks guys. Patrick

rustyfarmall · Jul 18, 2012

(quoted from post at 15:02:58 07/17/12) It's kicking my --- big time! Apparently the prior owner had the same problem because the square head was already rounded off, probably with a pair of vice grips. I just made it worse by trying the same thing.

Can I assume that it's an 1/8" NPT pipe plug? If so, not hard to replace.

I've got it soaking with some PB on the inside for now. I can only think of three options to try. First, heat plug a good cherry red, then try to wiggle it free with vise grips. I did remove the fuel adjusting screw, packing nut, and packing to avoid damage from the heat. Second, drill hole in middle and try backing it out with an easy out. Third, just leave it alone and not worry about it.

It's just a minor detail, but sometimes those minor details really eat on me.

I'm sure others here have had the same problem. Any other suggestions?

TIA, Patrick

Hopefully the carb is off the tractor AND disassembled? If so, grab your torch and heat the area around the plug cherry red. Let it cool a bit and then start dousing it with your favorite flavor of penetrating oil. It will smoke a little, but douse it again when the smoke stops and then walk away. Come back in about 30 minutes, grab that plug with your vice-grips and remove it. I've done it that way on every carb I've ever rebuilt and never damaged one. Yes, it is a 1/8" steel pipe plug.

NoNewParts · Jul 18, 2012

(quoted from post at 10:31:06 07/18/12)

(quoted from post at 15:02:58 07/17/12) It's kicking my --- big time! Apparently the prior owner had the same problem because the square head was already rounded off, probably with a pair of vice grips. I just made it worse by trying the same thing.

Can I assume that it's an 1/8" NPT pipe plug? If so, not hard to replace.

I've got it soaking with some PB on the inside for now. I can only think of three options to try. First, heat plug a good cherry red, then try to wiggle it free with vise grips. I did remove the fuel adjusting screw, packing nut, and packing to avoid damage from the heat. Second, drill hole in middle and try backing it out with an easy out. Third, just leave it alone and not worry about it.

It's just a minor detail, but sometimes those minor details really eat on me.

I'm sure others here have had the same problem. Any other suggestions?

TIA, Patrick

Click to expand...

Hopefully the carb is off the tractor AND disassembled? If so, grab your torch and heat the area around the plug cherry red. Let it cool a bit and then start dousing it with your favorite flavor of penetrating oil. It will smoke a little, but douse it again when the smoke stops and then walk away. Come back in about 30 minutes, grab that plug with your vice-grips and remove it. I've done it that way on every carb I've ever rebuilt and never damaged one. Yes, it is a 1/8" steel pipe plug.

The heat, penetrating oil quench is the way I do it too.
don't breathe the smoke.
after you get it out, a 1/8 threaded drain valve from the hardware
store makes a handy addition to any carb.

Patrick HMD · Jul 19, 2012

Wow, thanks for the tip on the drain cock. Gonna get one. I'm always up for a little embelishment.

Finally got it out today. Ended up using heat and pb blaster. Got the plug bright red, then started wiggling it with the vice grips. Felt good to see it finally break loose because I still had my doubts.

It seems so trivial now that it's done. But I'm sure there will be others just as stubburn when I start doing the tear down on the 49 M. Not there yet. I'm just trying to get it to run right for now. Finnish up the carb tomorrow, then start up on a gas tank flush, then coating. Once that's done I'll be in lot better shape.

Thanks guys. Patrick

Bottom drain plug on M carb won't budge

Patrick HMD

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Phil Tibbetts

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Patrick HMD

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TJV

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randy hall

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Phil Tibbetts

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teddy52food

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Patrick HMD

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rustyfarmall

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NoNewParts

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Patrick HMD

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