If the thread of the stud bolts on the cylinder, cylinder head, and the muffler flange is stripped or severe in rust, usually we want to replace them. Also, it is better to remove the stud bolt if we want to completely remove the gasket.
Here, let's focus on how to remove the stud bolts, considering the fact that unsuccessful extraction can lead to the worst situation.
Table of Contents
1. Ideally, apply a tightening torque near the tightening part
For a short bolts like an exhaust pipe flange, this is not a problem because the bolt is unlikely to be twisted during extraction. However, in the case of long stud bolts, so it is better to loosen the bolt by hanging the tool near the tightening part as much as possible.
2. "Stud bolt puller" are the tools I want to own
Many professional mechanics use and own different types of tools. This type of tool is like a deep socket wrench, it has a function in which three rollers inside bite into the stud bolts like a one-way clutch, then loosen and remove the bolt.
This is an example of how the usage varies depending on the length of the stud bolts, even if I use the same stud bolt remover (here I used KTC). Push the rotor directly against the screw thread and remove it. There are cases where new parts can be loosened with the double nut method, but it is not quite what I expected.
3. The ironclad rule is to use "thermal expansion" of the surrounding parts
It is not good to set the "stud bolt puller" at the normal temperature and start work immediately. At first, use an industrial hand heater (strong heater like a hairdryer) and gas burner around the stud bolts, the area around the stud bolts will expand by heating, and it makes the stud bolts easier to loosen.
4. Replace the stud bolts with a new one.
By removing the all the stud bolts, the gasket surface becomes flat. The gasket that has been stuck can be peeled off with the scraper, and the gasket surface can be made clean by using the oilstone. In case of performing the surface polishing of the cylinder base in the internal combustion machine processing, it is better to perform after removing all the stud bolts.
For the crankcase and cylinder heads, it has been incorporated with stud bolts. The cylinder and cylinder heads are fixed, fastened to the crankcase with nuts through stud bolts. When performing maintenance and tuning, I often want to remove this stud bolts.
When assembling the cylinder, install the base gasket to prevent oil leakage and it is an important rule when disassembling to replace a new gasket. If this base gasket is stuck, it is difficult to peel off. The stud bolts hinder the scraper to move, making hard to remove the stuck gasket smoothly. In this situation, there is a method to remove all the stud bolts. Without the stud bolts, I can use a scraper smoothly to remove the stuck gasket and easy to polish with an oilstone.
In addition, to fix the exhaust flange, the stud bolts are often used for the exhaust port of the cylinder head, and there are many cases where the thread of the stud bolts will be stripped due to the repeated attachment and detachment of muffler. For the new and good stud bolts, there is a "double nut type" that loosens the bolt and tighten each other using two nuts, but in reality, the stud bolt is difficult to come out easily.
In that case, a special tool called "stud bolt puller" or "stud bolt extractor" is necessary. There are various shapes and types of products that are different due to the demand of the users, but for the professional mechanic own tools of various types and shapes.
This is the product that loosens a single anti-slip core rod by biting it into the stud bolt. It incorporates three rollers inside the deep socket, which hold and loosen the stud bolts like a one-way clutch. Also, some products firmly clamp and loosen the thread of the stud bolts, but it is difficult to evaluate which type is the best and easy to use, and it is better to use them according to the shape and situation of the parts which the stud bolts are installed.
However, when removing any stud bolts, it is important to ensure that the surrounding area of the bolt is heated firmly so that the components will thermally expand. After the thermal expansion is performed, it is also good to use a method of spraying a rust preventive penetrating oil onto the screw portion to increase the loosening effect with the power of the chemical.
1) Use various types of special tools depending on the situation
2) Before starting to work, heat the tightened parts and let it thermally expand
3) Use chemicals such as anti-rust remover spray during thermal expansion
