BC (before covid), I was in shops on almost a weekly basis. I always make a point to visit with not only the builders and diagnosticians, but also with the R&R specialists. The R&R technician is the most underrated person in most shops today. I typically walk away amazed at how proficient these folks are and at the level of commonsense knowledge many of them possess. In my opinion, they have one of the most difficult jobs in the building and I know for certain that I would go broke if I had to do their job. We try to put some R&R tips in the seminar each year because they too deserve our attention. That is the reason for this article, as we have all experienced bolts that break and it can make for the day from hell, if things do not go right.
So, you may be wondering why do bolts/studs break off? Generally, one of two things happen. Expansion and contraction from the bolt/stud heat cycling causes the threads and shank to stretch. This leads to a smaller cross section, so when torque is applied, the bolt breaks. The other issue is corrosion developing between the male and female threads. In either case, if the bolt fractures, you may be in for a lot of work. Like you, I have experienced my share of broken bolts and studs and many times it can be a challenge to get the broken pieces removed without major work and a lot of choice words. Lots of techniques and tools are available to help if you have the misfortune of this happening to you, so let’s take a look.
THINGS TO REMEMBER:
Patience is your friend. Do not get in a hurry trying to loosen the bolt/nut. Work the bolt/nut back and forth slightly as you attempt to remove it, as this will help to break the bond between the threads. If you are using chemicals, let them set for an extended period of time before you try move the bolt/nut.
Most technicians agree that it is best to slightly tighten the bolt/ nut before you try and loosen it if you suspect that you may have a problem.
If it seems that the bolt/nut is not budging or if you are concerned that you are feeling the bolt starting to stretch, STOP! It’s time to develop a new strategy before you break the bolt…
If you have the misfortune of breaking the bolt/stud, then how you proceed next will make or break your day. Lots of different techniques and tools are available.
Penetrating oils are the most common product used by shops. Technicians have their favorites and whatever works for you is great. Many technicians make their own penetrating oil from Acetone and Automatic Transmission Fluid. A 50/50 ratio makes a very good penetrating product. I have used this for years and it works well. The key to penetrating fluids is patience, as it takes a long time for them to work and you may have to apply them multiple times (Figure 1).
This is an old school solution dating back to the sailing ship days but it works fairly well in many instances. Candle wax (paraffin) can be used to penetrate and lubricate the corroded threads. Heat the threaded area that is stuck with a propane/map gas or oxygen acetylene torch. With the broken bolt/ stud hot, place the wax on the corroded area. Capillary action will draw the wax into the threads so you can then remove the bolt/stud. Let the stud/bolt cool for 20-30 minutes before you try to remove the fractured stud/bolt.
BLUNT FORCE, IMPACT
Striking the end of the broken bolt/stud with a hammer will many times fracture the corrosion which is preventing you from removing the bolt/stud. If your aim is not so good, you may want to consider using your air chisel, equipped with a blunt/flat driver bit. I commonly use this method and it works well because it fractures the bond between the male and female threads without a lot of work. Typically, if I think I may have an issue with a bolt/nut I will use this process prior to attempting to loosen the nut/ bolt.
Heat is a common technique that is used to address corroded bolts/nuts. Depending on who you talk to, some technicians use a map gas torch while others use an oxygen acetylene torch. Most technicians will heat the broken stud/bolt until it turns red hot, then let it cool prior to attempting to remove the broken piece.
In many cases, it is impossible to get a torch into the area of the broken stud/bolt without damaging wiring or components. An alternative to using a torch is to use an induction heating tool on the broken stud/bolt. Unlike an open flame, the tool is safe to use around wiring and other components. The tool is plugged into an electrical outlet and when you pull the trigger, the tool coil that you placed around the part, will start to heat the part (Figure 2).
You can heat the stud/bolt as much as you want all the way up to red hot. Since gaining access to one of these tools, I now use it prior to attempting to remove any bolts/nuts that I feel may want to cause me problems. This type of tool has been around for many years but the size and price have dropped significantly the last few years. These tools were designed for the heavy equipment industry but also work great for automotive and heavy truck products. My first exposure was at a heavy equipment shop where we used it to remove track pins on a dozer. If you do not own one, I would highly suggest that you look at purchasing one as they work well.
I have spoken to many shops that have induction heaters and many technicians feel that it works best if you wait for 20-30 minutes after your heating process was completed before you attempt to remove the broken parts. Reheating/cooling the part multiple times is not uncommon when using this technique. Remember, patience is your friend and waiting allows the surfaces to contract as they cool, hopefully breaking the corrosion bond. Some technicians apply penetrating oil or wax to the parts during the cool down process.
VISE GRIPS OR A PIPE WRENCH
To turn the stud or broken bolt, I will generally use vise grips or a small pipe wrench. I am now using a pipe wrench more than ever simply because I no longer have the gripping strength to close the vise grips when the tension is high enough to firmly grab the broken stud/bolt. (Getting older is not for the faint of heart)
Stud/bolt extractors are available in two different versions, tools that allow you to remove bolts/studs that are broken off flush/below flush and tools that service parts that have enough exposed to allow you to attach a tool to assist.
“Easy outs” are contrary to their name and are designed for studs/bolts that are broken off flush or below. The key to using an easy out are two things, the broken part must be drilled to allow you to position the easy out in the drilled hole. The hole must be perfectly in the center of the broken bolt. If the hole is offset to one side or the process fails to work, drilling out the broken stud/bolt becomes much more difficult. The other issue is that the easy out is made of hardened steel so it can easily break. If broken, it can be difficult to impossible to extract the broken tool without a lot of work.
The other type of tools allows you to grab the exposed area of the broken stud/bolt. Most are cam designs so the further you rotate the tool the tighter it grabs the broken stud/bolt. Just like when using a pipe wrench/vice grips, patience is an asset as you can easily over power the stud/bolt breaking it off again (Figure 4).
LEFT-HANDED DRILL BITS
Sometimes when a stud/bolt is broken off flush or below the surface it can be removed by using a left-handed drill bit. This process works well on those bolts/studs that are not severely stuck. Many technicians use left-handed drill bits to drill out the stud/ bolt in preparation for using an easy out type extractor in the hope that if they are lucky, it will spin the broken bolt out.
If you choose to fully drill out the broken stud/bolt cut/grind the bolt off flush with the surface if its protruding. Center punch the exact center of the bolt/stud. Start with a small bit and increase the bit size slowly. When fully drilled out, use a pick or chisel to remove the bolt/stud pieces.
If you can remove the component, remove it and drill out the broken stud/ bolt using a drill press. If you cannot remove the component, consider using a ‘Magnetic Drill” rather than a hand drill. Mag drills allow you to hold the drill precisely in the desired position as you operate the drill.
HINGE SIGHTING DRILL BITS
Some shops use the same type of tool used for wood working to guide their drill bits. Hinge sighting drill bits are available in various sizes and are designed to center the drill bit in the area that you will be drilling your hole.
WELDING ON A NUT
If the stud/bolt is protruding you can, many times, weld a nut or nut/ washer onto it. A socket or wrench can then be used to remove the broken piece. The expansion/contraction created by the welding process will many times break the corrosion bond allowing the piece to be removed.
Many times, a bolt/stud will be broken off below the surface. Welding a nut and/or washer/nut onto the broken piece without causing damage to the bore/threads can be a challenge. Many machine shops use a piece of copper tubing that has been sized to fit in the hole against the threads. Using a mig welder, they fill the bore of the tubing with fill. Once tall enough, a nut/washer are welded onto the fill allowing you to rotate the stud/bolt.
X-TRACTALLOY STUD EXTRACTOR ARC WELDING ELECTRODE
This is one of the neatest products I have ever seen used. X-tractalloy arc welding rod is designed to stick only to steel and not to cast iron or aluminum. The rod has a special ceramic flux to keep it from sticking to the threads. So, as you strike the arc on the broken piece, the fill will start to build and you can simply keep welding until it is sticking out far enough for you to weld a nut/washer onto it.
Machine/welding shops commonly use this type of rod to remove not only broken bolts/studs but also broken off taps and easy outs. It is expensive but well worth the cost when you need a solution to your problem.
Companies like ProMaxx and Lisle have developed product specific tools to help you with difficult broken bolt removal jobs. These specialty tools are designed for a specific product problem on applications such as Ford Eco boost, Ford Diesel, GM and Dodge Diesel which commonly have broken bolt issues. These tools make the job much easier and faster on the applications covered but, each application requires a different tool package so it can get spendy.
As you can see, there is a lot more to removing a broken bolt/stud than one may realize at first glance. Even with the best tools and techniques this process can be a challenge. Like you, I get frustrated when I need to remove a broken bolt/stud, and like some, I tend to rush the process. So relax, take a break and have patience with the process as it can and usually does take a lot of time.
Until next time remember, “have patience, all things are difficult before they become easy”.