Broke head off bolt.....need advice

[CassidyNZ]

In my humble opinion, using an easy out that is nearly the size of the bolt will cause the bolt to expand as the tool forces its way in, causing the bolt to get tighter not looser. The easyout needs to be big enough not to break, small enough to prevent expansion.

Let’s face it, if the bolt is seized and that unfortunate condition cannot be changed with penetrating oil and/or heat, an easyout ain’t going to work. Easyouts were designed to remove loose-ish bolts that have broken off flush, they’re brittle, not strong.

[Dogscout]

If there is still stud sticking out then get yourself one of these. They come in various sizes. Vice grips are a foolish waste of time. They are good for grabbing something securely but not good at turning a broken stud.

[lovinlifebda]

Thanks to everyone, we went out with friends for the evening shortly after posting and so I only checked again this morning. Was totally impressed with so many replies and the quality of the replies.

First thing today the anti seizing spray will begin, new bolts will be sourced and then I will follow advice on removal. Will follow up the thread when there is some outcome to report. Jim

[bluenoser613]

If all else fails I've seen others weld a nut on the end, putting a washer in between to make the weld easier.

[Cheechako]

If the vise grips dont do it first try, shock the protruding bolt by punching it on the end, in the direction of the bolt shank, with a blunt punch and hammer. Brass punch even better. This will often release corroded threads better than any penetrating oil type, which often wont even soak in there.

[a64pilot]

The weld a nut thing is very good, I think a lot of it’s success is due to heating the broken bolt a high heat, this expands it of course and may help break it free.
Issue is of course you have to have access to a welder, I’d advise against attempts using your battery bank unless your experienced in doing so.
Or at least practice on something else until your comfortable you can do it.

[Taipe]

Totally agree with using cobalt bits if you have to drill, but you would want to order a set with 1/64" increments and take your time to as you get to the final hole size to match the largest easy-out that fits the size of the broken screw. Also, a cutting lubricant keeps the point of the bit from overheating which keeps the drill bit point sharp. For a penetrant chemical, it's hard to beat Kano Kroil when other penetrants fail. The 8mm-25 stamp on the head of the bolts most likely is an abbreviation for the thread pitch of 1.25 mm of screw length/each full turn of the screw. Replace it with 8mm. x 1.25. And you don't need to get it from Yanmar. Order Grade 8 steel alloy (as a general rule, avoid stainless steel bolts on engines b because it is not as tuff). McMaster-Carr sells the drills bits and the fasteners and ships overseas all the time. You also ought to purchase a Starret brand spring-loaded center punch. When there isn't enough screw exposed to double-nut it or to get a bite on it with vice-grips, carefully flatten the broken end with a file before using the center punch. I know it can take time for orders to clear your local customs agent. The alternative is to ask around for who is expecting a reliable friend who is flying down for a visit.
Wishing you all the best!

[Dougtiff]

Well, if you don't have time to do the repairs before heading to the haul out, rig up a 12 volt pump to get you there.

[Ken Z]

I agree that easy out is close to last resort, if needed use the largest size without harming threads. Use a sharp punch to make a start for drilling and use a bit at least 1/2 the size of the bolt, drill slow and cutting oil helps. Liquid wrench is low on the list of pent. oil . pb blaster is better, but kano knoil pent. oil is good, also locktite 8040 freeze and release, crc feeze off super lube and dupont deep freeze pent. oil can work wonders. I realize your location and choices Vice grips and 24-48 hrs soak time are needed. Some vice grips have a curved mouth others are straighter, if possible use the straighter style and use two hands and a firm setting to get a bite. Rotate in two directions to loosen. Last resort drill and retap and motor slowly. good luck

[lvictorlucas]

Several of the things I would try have been stated in the previous posts. I would also try heat from a propane torch. If some of the bolts remain showing after you remove the cover plate you can use a pair of Vice Grips or similar to hold the plate on since the water pressure is low. Attach them inline with the bolt then rotate them toward 90 degrees to apply pressure to the plate. A strap around some point on the engine with something used as a spacer will also work. Use a Spanish Windlass if it is not a ratcheting strap or for more pressure.

[captlloyd]

Originally Posted by CassidyNZ

In my humble opinion, using an easy out that is nearly the size of the bolt will cause the bolt to expand as the tool forces its way in, causing the bolt to get tighter not looser. The easyout needs to be big enough not to break, small enough to prevent expansion.

Let’s face it, if the bolt is seized and that unfortunate condition cannot be changed with penetrating oil and/or heat, an easyout ain’t going to work. Easyouts were designed to remove loose-ish bolts that have broken off flush, they’re brittle, not strong.

You have got that right mate, 74 years old and never had bit of success with an easy out. Lots of very good tricks on YouTube for dealing with broken bolts.

[sailah]

My (considerable) experience with removing broken bolts:

Often when a head snaps off it's not terminal as the pressure has been released on the threads. I don't think this is the cast here for you since it appears corrosion is the enemy.

I would rank the following treatments in terms of effective:

1) Heat, try and heat the surrounding metal, and then cool the bolt with ice. Repeat.
2) Heat
3) Heat
4) Welding nut to stud and backing out (See A64 comments, he's totally right it's the heat that truly helps). Having a TIG welder helps a lot
5) Kroil or another quality penetrant
6) Time, be patient
7) Tighten, then loosen in tiny steps. Go back to step 1.
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99) Drilling out, very high risk of making it worse unless you are extremely skilled with a drill. Grind/file stud so it is perfectly flat. Use prick punch to center punch stud. Drill very carefully being sure to remain on axis. You can't be too careful here. If you wander off or cheat on the above steps you'll make a bigger mess. Left hand drills don't work very well in handheld drill applications. I've used them on my Bridgeport effectively but that's because I can put a lot of quill pressure on bit. Just regular high speed steel drills are fine for a normal bolt. Do yourself a favor and buy the newest most expensive bit you can find like an M4 size. Assuming you drilled totally on center with this pilot you can go up in size.

When I do this operation on my mill, I center up on stud by grabbing stud with drill chuck. Then I face off the stud using end mill. Then center drill using a center drill. Then a pilot hole. Then bigger. I can usually drill out to the root of the threads and remove the threads with a pick. But you likely can't replicate that precision with a handheld drill.

Often I'll attempt the left hand drills when doing pilot since I can put a lot of downward pressure on bit and sometimes it will walk out. Worth a shot since I'm drilling a hole anyways.

100) Ez Out used with above and as an absolute last resort. They are hardened and super brittle. If you break one, you need to smash it to get it out or EDM it. Been there done that. It's a total artform to learn just how much pressure to apply to EZ out because they work right up until, SNAP.



Good luck, it's a great skill to have to be able to remove a broken bolt as it likely won't be the last. Just be patient, rushing into a fix and wrenching it with visegrips without following the steps is a surefire way to make situation worse.

[Shawn67]

As an alternate to cooling the bolt with ice get a can of compressed air. Use the straw applicator and spray the bolt with the can upside down. It will chill it very quickly.

Shawn

[lovinlifebda]

Update, Just got the second bolt out. Have been putting PB Blaster on it since yesterday morning. Bought a propane torch and heated the bolt three times, putting Blaster on it as soon I took the torch away. With some trepidation I put the wrench on it and it turned. So that bolt is out and the end cap is off. There is corrosion on the bolt and so it will need to be cleaned up before reusing.
Now for the broken bolt, will use the Blaster on it every time I think of it over the next couple of days. Have already heated it once and will do that a few more times. Then I will carefully try the vice grips, I am no welder and there is not enough room for two nuts.

Another question. You would think I could find a standard M8x25 bolt...oh not so. Still on the hunt but have only found metric bolts in SS. Could I use a SS bolt with Tef-Gel for a couple of months, we have friends coming down in September and they could bring the bolts.

[Boatwright]

You don't need a "diesel mechanic" to remove a wrung off bolt - just a good mechanic. I would ask around for the local guy who can fix anything. I have seen amazing things done by mechanics used to working with minimal tools and supplies.

I would make sure a replacement bolt of the right size is available before you tear things down.

Excellent advice on using penetrating oil and gently rocking the bolt both ways. Vice grips can make things worse unless the bolt is easily turned to begin with. Easy-outs are anything but easy, and require careful drilling with the proper sized left-hand bit dead center. Easy-out failure often requires a trip to the machine shop.

Good luck.