Removing Stripped Or Frozen Bolts And ScrewsBy Tom Neale
Photos by Mel Neale
Published: October/November 2012
Frozen bolts can be maddening. Tom suggests a series of tactics from lubricants to brute force to get the darn things out.
You've been there. No matter how hard you try, that bolt won't come out. This can turn a five-minute job to one that takes days, resulting in a horribly expensive mess. There are tactics and tools that will often solve this problem, although I admit I've sometimes longed for a stick of dynamite. Patience, vibration, and wise use of force are key.
Doing the wrong things can wrench off the bolt head or strip the slot in the top of the bolt. Hopefully your bolt will have a head, such as a hex head, around which you can fit a socket or closed box wrench. If this isn't what you have, most good builders use sensibly shaped holes, such as the various Phillips type shapes, in the head for better tool gripping. Unfortunately, a few builders still use bolts with straight-edge slots, which easily round out. These require special caution. If your fastener has a rounded-out slot, you can often cut another slot into the head with a Dremel tool. There is no limit to tricks that good mechanics use. Generally, the information below applies to all bolts if you use the correct bit, socket, or wrench.
If your bolt doesn't turn after moderate pressure, first spray on a product like PB Blaster or CRC's Freeze-Off. The former is representative of products that have a lubricant, which will work its way into very tight corroded surfaces. CRC Freeze-Off also has penetrating lubricant but adds the feature of contraction caused by temperature differential. This product, if used properly, significantly chills or even freezes the bolt, causing it to contract, which hopefully facilitates entry of penetrating lubricant and separation of the corrosion. Usually it takes a lot of spraying, but when it works, it's worth it.
If the chemicals don't work, begin patient tapping to set up vibration. After each tapping session, add more penetrant. Depending on the situation, use a hammer directly on the bolt or on a box-end wrench that's held squarely and securely over the bolt head and torqued tightly by hand in the "unscrew" (usually counterclockwise) direction. This tapping not only sets up vibration but also, hopefully, tends to turn the bolt in the right direction as the vibration begins to separate the bind. Sometimes this process may take a few moments, sometimes days. Neither the hammer nor the blows should be too heavy. The goal is to create vibration, not immediately force the bolt to turn. If your hammer can't reach the bolt, you can transmit its blows to the bolt using a heavy-duty hardened-steel straight drift pin or similar tool, flat on each end, made for this use. Wear eye protection.
If you still have no success, try heat from a torch. Most people use a propane torch, but other sources generate far more or less heat. What you use will depend on what you're heating (remember, heat will transmit from the bolt to the surrounding metal), your familiarity with the source of heat, and of course, where you're working. It's seldom, if ever, a good idea to use open flame belowdecks, no matter how careful you are. Most use the simple inexpensive propane torch with easily handled, inexpensive canisters. The heat should be applied according to instructions for the products you're using. But generally, the tip of the flame should be just touching the bolt. As a practical matter, you'll probably want to direct the heat to the bolt rather than the surrounding metal because you may not want to damage the surrounding metal. And that metal, because of its mass, will probably consume the heat and spread it out before it does any good. If you're trying to remove a nut from a bolt, you should probably apply the heat or cold to the smaller nut.
After heating, try more tapping as well as more heating, if needed. After heating and tapping, spraying in a lubricating penetrant like those mentioned above often helps. With the effects of the heat and tapping, there may be more of an opening for this type of product to enter. Wait for the metal to cool; spraying one of these products on hot metal can cause fire and explosion.
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Tech SupportDegree Of Difficulty
Materials and Costs:
- Tef-Gel, $14 for 12-oz. tube
- Manual Impact Driver, $23 Craftsman
- AC Impact Driver approx. $100 to $300 (depending on brand and store)
- Propane Torch approx. $15 to $25
- Cheating Bar - You probably already have one…
- CRC Freeze-Off approx. $7 to $14, depending on size
- EZ-Out Set approx. $20 to $30, depending on size of set