Broke head off bolt.....need advice

[Boatwright]

One more thing: The stud wrench pictured in a previous post is the best tool to try. The guy who can fix anything should have one in his tool box.

[sailah]

Originally Posted by 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.

I would not reuse the bolt personally. If you need to, a SS wire brush will clean them for reuse. I use copper anti seize although tef gel will work if you have it.

Might be a good idea to run a tap in the threads to clean things up.


SS is fine to use in this type of application. Not as strong as carbon steel but this doesn't sound like a high strength application. I'd use whatever you can get your hands on. M8 bolts are extremely common in vehicles and motorcycles maybe if you can't find one in a traditional sense you could go to a junkyard or vehicle mechanic and see if they have one.

I'm spoiled with Bolt Depot in my town as well as McMaster next day delivery.

[leftbrainstuff]

This is not a problem unique to Yanmar.

If there is more than a thread diameter of thread frozen then removal by unscrewing is probabilistically less likely. So drilling out is a proven approach.

If the bolt is low grade, less than say grade5 then drilling out is relatively easy.

If the bolt is seized in corroded alloy then you'll likely pull all the female thread portion and will have to helicoil or similar.

If the thread is exposed vice grips can work. Also welding to the broken head works well. I've tig welded very small studs (1/8in diameter). Stick or rod welding works well in a hole and for larger threads (1/4 inch) up.

Good penetrating oil works well. Diesel and atf with some heat works well. Kroil oil or mouse milk is also good on finer threads

Sometimes impact forces help.

And sometimes I'll make a drilling jig to ensure an accurate drill out works.

I've used electrode discharge machining on very expensive alloy engine blocks and aerospace parts but this is too specialist for this forum.

[s/v Jedi]

Many boats (most if not all steel boats) carry a small portable welder. Ask around the anchorage ��

[model 10]

I thought everybody used a plasma cutter to burn out broken off bolts? That's how they do it these days, but back in the day you could burn out bolts in a cast iron casting with a cutting torch. Clean up the hole with a tap and you were good to go.

[Stingo]

Originally Posted by Boatwright

One more thing: The stud wrench pictured in a previous post is the best tool to try. The guy who can fix anything should have one in his tool box.

I've just looked on ebay for a "stud wrench" and can't find anything similar to the one in the pic from the previous post. Is there perhaps a different name for them?

[IslandHopper]

Originally Posted by Stingo

I've just looked on ebay for a "stud wrench" and can't find anything similar to the one in the pic from the previous post. Is there perhaps a different name for them?

https://www.amazon.com/Spurtar-0-2-I.../dp/B07B3S1CJN

https://www.google.com/search?rlz=1C...ih=625#imgrc=_

[Steve Bean]

Some say the best and cheapest penetrating oil is 50:50 transmission fluid and acetone. I've been experimenting with it.

[s/v Jedi]

Originally Posted by Steve Bean

Some say the best and cheapest penetrating oil is 50:50 transmission fluid and acetone. I've been experimenting with it.

Everything has been done before
He has a part 2 as well
https://youtu.be/xUEob2oAKVs

[a64pilot]

Originally Posted by lovinlifebda

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.

I’ve used SS bolts and tefgel for five years now, no problems so far.
I believe the heat ex the bolt screws into is cast iron with an aluminum cap? If so then I’d be even less worried about a SS bolt, but be careful with them as most SS bolts are 18-8 or 304. Your choice as what to call them, but they are soft and not as strong as a grade 5 steel bolt.
Hardware store bolts are often junk and are not usually grade 5

[a64pilot]

Originally Posted by s/v Jedi

Everything has been done before

He has a part 2 as well

https://youtu.be/xUEob2oAKVs

Issue I have with his testing was it was artificially oxidized. Meaning that what was oxidized was only the external parts, not the threads between the nut and the bolt.
In his case heat worked best I believe because it expanded the bolt, making it longer so there was less friction between the nut and the angle iron.

But usually the issue is internal corrosion, not external on exposed threads.

I would assume his test ought not be break away torque, but running torque on the rusted threads, cause I bet there was no rust under the nut between the nut and the bolt.

So how do you test that without waiting ten years? I have no idea.

[Wotname]

Originally Posted by 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.

Thank you!

As a self taught DIYer of older mechanical metal stuff I have considerable experience with broken / seized / corroded studs / bolts and I was very practiced in doing it the wrong way - almost always with bad results. i.e. I would start at out #100 and work back to #99 etc.

Slowly I have learnt heat and patience is the best way to get positive results and with way less damage to surrounding metal. I still have much more learning to do .

Your advice is gold!

[HopCar]

I’ve always had the best luck freeing a stuck bolt or screw by heating the surrounding metal. If you have a hole in a piece of metal and heat the metal, the hole gets bigger in diameter.

I like sailah’s suggestion to then cool the bolt with ice. That would cause the bolt to shrink.

Heat the hole bigger, cool the bolt smaller and it breaks free.

An outboard mechanic friend of mine called his torch a fire wrench. He didn’t fool around with propane, he used oxy/acetylene.

[Wotname]

Originally Posted by HopCar

I’ve always had the best luck freeing a stuck bolt or screw by heating the surrounding metal. If you have a hole in a piece of metal and heat the metal, the hole gets bigger in diameter.

I like sailah’s suggestion to then cool the bolt with ice. That would cause the bolt to shrink.

Heat the hole bigger, cool the bolt smaller and it breaks free.

An outboard mechanic friend of mine called his torch a fire wrench. He didn’t fool around with propane, he used oxy/acetylene.

Or use freeze spray in lieu of ice, gets it colder and easy to direct the spray onto the right area but certainly more expensive than ice.

https://crcindustries.com.au/product...300g-2039.html

[Boatwright]

Try Stud Remover. This tool has a knurled cam that grips the fastener.