Service Technology, Tools and Workshop Equipment

Service Methods

There are several methods for performing vehicle maintenance and repair procedures, which are referenced in the text of this manual. Following them will make the home mechanic's work more efficient, allow various technical procedures to be organized and performed to the best quality, and ensure that all work is thorough and complete.

Fasteners

Fasteners are nuts, bolts, studs and screws used to join two or more parts together. When working with fasteners, some things must always be kept in mind. Virtually all fasteners use some type of locking or retaining device. These can be lock washers, jam nuts, cotter pins or thread-locking compound. All threaded fasteners must be perfectly clean and straight, with undamaged threads and sharp, undamaged corners on the hex heads where the wrench fits. It is a rule to always replace damaged nuts and bolts with new ones. Special self-locking nuts with nylon or fiber inserts must not be reused, since they lose their locking properties when removed and must always be replaced with new ones during installation.

Rusted bolts and nuts should be treated with a penetrating fluid before removal to make loosening easier and to prevent damage. Many mechanics prefer to use kerosene for this purpose, which is conveniently applied from a small can with a long spout. After soaking seized fasteners with penetrating fluid, allow the fluid several minutes to thoroughly penetrate the corroded contact surfaces before attempting removal. Heavily rusted fasteners may be cut off with a chisel, sawed off with a hacksaw, or removed with a special stud extractor.

If a bolt head is sheared off or a stud breaks during installation or service, the remaining threaded portion may be drilled out or removed with special tools. Most automotive repair shops can perform this procedure, as well as other repair procedures (for example, repairing damaged threads in threaded holes).

Flat washers and lock washers must always be installed in the same position and in the same manner as before. Always replace damaged washers with new ones. Flat washers must always be installed between a lock washer and a soft metal surface (such as aluminum), thin sheet metal or plastic.

Fastener Dimensions

For many reasons, vehicle manufacturers are increasingly using metric fasteners. However, it is important to know the difference between standard (also called American or SAE) fasteners, which are sometimes used, and metric fasteners, which are more common, since despite their outward similarity they are not interchangeable.

All bolts, both standard and metric, are classified by diameter, thread pitch and length. For example, a standard 1/2 - 13 x 1 bolt has a diameter of 1/2 inch, 13 threads per inch and a length of 1 inch. A metric M12 - 1.75 x 25 bolt has a diameter of 12 mm, a thread pitch of 1.75 mm (distance between adjacent threads) and a length of 25 mm. Both bolts look nearly identical, but they are not interchangeable.

In addition to these characteristics, both standard and metric bolts can be identified by examining the head. First, the distance across the flats of a metric bolt head is measured in mm, whereas for a standard bolt it is measured in inches (the same applies to nuts). As a result, a standard wrench is not suitable for metric fasteners, and vice versa. Also, most standard bolt heads have radial marks indicating the maximum permissible tightening torque (strength grade). The more marks, the higher the permissible torque (automotive bolts typically have strength grades from 0 to 5). The strength class of metric bolts is indicated by a numeric code. The code digits are usually embossed on the bolt head, as with standard bolts (automotive bolts typically have strength classes 8.8, 9.8 and 10.9).

Bolt Strength Class Markings (top - standard /SAE/USS, bottom - metric)
1 – Strength class 1 or 2
2 – Strength class 5
3 – Strength class 8
4 – Metric bolt strength class marking

Dimensions/Strength Class Markings of Standard (SAE and USS) Bolts
G — strength class marking
L — length (in inches)
T — thread pitch (number of threads per inch)
D — nominal diameter (in inches)

Dimensions/Strength Class Markings of Metric Bolts
P — strength class
L — length (in mm)
T — thread pitch (distance between adjacent threads in mm)
D — nominal diameter (in mm)

Standard nuts can also be distinguished from metric nuts by their strength class markings. Strength classes of standard nuts are identified by dot marks stamped on one of the end faces of the nut, while metric nut markings are made with numerals. The more dots, or the higher the numeric code value, the higher the permissible tightening torque of the nut.

Standard Hex Nut Strength Class Markings

Hex Nut.
Strength class 5
Class identification: Three dots

Hex Nut.
Strength class 8
Class identification: Six dots

Metric Hex Nut Strength Class Markings

Hex Nut.
Strength class 9
Class identification: Arabic numeral 9

Hex Nut.
Strength class 10
Class identification: Arabic numeral 10

The ends of metric studs are also marked according to their strength class. Large studs are marked with a numeric code, while smaller studs are marked with a geometric shape.

Metric Stud Strength Class Marking
Mark 1 — Strength class 10.9
Mark 2 — Strength class 9.8
Mark 3 — Strength class 8.8

It should be noted that a significant portion of fasteners, especially those of strength class 0 to 2, are not marked at all. In this case, the only way to distinguish standard fasteners from metric ones is to measure the thread pitch or compare the thread with a uniquely identified one.

Standard fasteners are also often called, as opposed to metric, SAE fasteners; however, it should be remembered that the SAE classification covers only small fasteners. Large fasteners with non-metric threads are American Standard (USS) fasteners.

Since fasteners of the same nominal size (both standard and metric) may have different strength classes, when replacing bolts, nuts and studs on the vehicle, pay attention to whether the strength class of the new fastener matches the strength class of the old one.

Tightening Procedure and Sequence for Threaded Connections

Most threaded connections should be tightened to the torque values specified in the Specifications at the beginning of each Section of this Manual (the tightening force applied to a fastener is understood as the torque applied to it during tightening). Hereinafter, this tightening force is also referred to as the fastener torque. Overtightening may damage the fastener, while undertightening leads to an unreliable connection of the mating components. Bolts, screws and studs, depending on the material from which they are made and the diameter of the threaded portion, usually have strictly defined permissible torque values, many of which, as mentioned above, are listed in the Specifications at the beginning of each Section. Strictly follow the torque recommendations for the fasteners used on the vehicle. For fasteners not listed in the Specifications, use the torque chart below. The values in the table are intended for fasteners of strength classes 2 and 3 (higher-class fasteners may be tightened to higher torque), and it is assumed that dry (non-lubricated thread) fasteners are being tightened into a steel or cast iron (not aluminum) component.

Fasteners arranged around the perimeter of a component (such as cylinder head bolts, oil pan bolts and various covers) must be loosened and tightened in a strictly defined sequence to prevent distortion of the component. The tightening and loosening sequence for such fasteners is given in the relevant Sections of this Manual. If no specific sequence is specified, follow the procedure described below to prevent warping of the component. In the first stage, all bolts or nuts must be snugged by hand. Next, each one in turn must be tightened by one full turn, moving from one bolt/nut to another in a diagonal (criss-cross) pattern. Then, returning to the first bolt/nut, repeat the procedure in the same order, tightening each fastener by an additional half turn. Continue in the same manner, tightening each bolt/nut by a quarter turn per pass until all of them are tightened to the specified torque. When loosening fasteners, follow the same procedure in reverse order.

Disassembly of Components

All components must be disassembled in such a way that during reassembly each part can be installed in its original location and in the correct orientation. Memorize characteristic features of appearance, and if necessary, mark the mating positions of parts that can be installed in more than one way (for example, a thrust washer with a groove on a shaft). It is a good idea to arrange removed parts on a clean work surface in the order in which they were removed. Simple schematic sketches or step-by-step photographs of the component to be disassembled are also useful.

When removing fasteners, try to mark their original position on the assembly. Often, immediately reinstalling fasteners and washers in their original positions after removing the relevant part helps avoid confusion during reassembly. If this is not possible, all fasteners should be placed in a specially prepared box divided into sections and labeled accordingly, or simply in individually marked containers. This approach is especially useful when working with components consisting of many small parts, such as fuel injection system components, the alternator, the valve train, the instrument panel or interior trim elements.

When disconnecting electrical contacts and connectors, pay attention to labeling wires or harnesses using insulating tape with a numeric or alphabetic code written on it.

Gasket Surfaces

On all vehicles, gaskets are used to seal the joint between two or more mating components and serve to prevent leakage of oils and fluids and to maintain elevated pressure or vacuum inside the assembly.

Often such gaskets are coated with a liquid or paste sealing compound before installation. Over time, under the influence of temperature or pressure, mating surfaces may become so strongly stuck together that separating the components becomes difficult. In many cases, tapping the outside around the perimeter of the joint with a soft-faced mallet helps to separate such assemblies. A conventional hammer may also be used, striking through a wooden or plastic block. Do not tap cast housings and fragile components. If such difficulties arise, always first check that all fasteners have been removed.

Avoid using a screwdriver or pry bar inserted between mating surfaces to separate components, as sealing surfaces can easily be damaged, which may later cause leaks. If prying of stuck assembly parts cannot be avoided, use the handle of an old brush for this purpose, but remember that afterwards all resulting chips must be thoroughly removed from the mating surfaces and from inside the assembly.

After separating the parts, their mating surfaces must be carefully cleaned, scraping off all traces of the old gasket material. Hardened remnants of the old gasket may first be softened using rust converter or a special chemical compound, after which they can be removed from the mating surface with a scraper. A piece of copper tube with a flattened and sharpened end may be used as a scraper in this case. Copper tube is recommended for this purpose because copper is usually softer than the materials used in the vehicle, which reduces the risk of damaging the mating surface. Some gaskets can be easily removed with a copper wire brush; however, regardless of the method used, the mating surfaces must be absolutely clean and smooth. If the mating surface has been scratched for any reason, fill the scratch with gasket sealant before assembling the components. In most cases, a non-hardening (or semi-hardening) sealant should be used.

Hose Removal Tips


If your vehicle is equipped with an air conditioning system, do not disconnect any hoses from air conditioning components until the system has been discharged by a BMW dealership or an air conditioning specialist at a repair shop.

The precautions to observe when removing hoses are very similar to those for removing gaskets. Avoid damaging the surfaces of the fittings and pipes onto which the hoses are fitted, as this may cause leaks. This applies especially to removing radiator hoses. Due to various chemical reactions, the rubber of hoses may stick to the mating surfaces of fittings and pipes. To remove a hose, first loosen the clamp securing it to the fitting. Then, using sliding-joint pliers, grip the hose near the clamp and begin rotating it back and forth on the fitting/connecting pipe. Continue this procedure until the hose is fully free, then remove the hose from the fitting. A small amount of silicone or other lubricant will make the procedure easier if it can be introduced into the gap between the fitting and the hose. To make hose installation easier, lubricate the inner surface of the hose and the outer surface of the fitting.

As a last resort, or where replacement of the hose with a new one is clearly necessary, the end of the hose fitted over the fitting may be cut with a knife and then separated from the fitting surface. When doing so, try not to damage the metal of the fitting/connecting pipe with the knife.

If the hose clamp is damaged, replace it with a new one. Crimp-type clamps usually loosen over time, so regardless of their condition, it is better to replace them with screw-type clamps whenever possible.

Tools

Selecting good tools is one of the basic requirements for anyone planning to perform vehicle maintenance or repair procedures themselves. At first glance, the costs associated with purchasing the required set of tools may seem too high; however, when compared with the costs of routine maintenance and simple repairs performed at a service station, they prove quite reasonable.

To help the average vehicle owner select the tools needed for the various procedures described in this Manual, three tool sets are listed below, conditionally titled: routine maintenance and minor repair tool set; general and major repair tool set; and special tools. Owners without practical mechanical experience should start with procedures limited to the use of tools from the first list, gradually improving their skills and expanding the range of tools they use. As experience is gained, more complex tasks can be undertaken, supplementing the tools on hand. After some time, the skills acquired will allow more complex work requiring tools from the second list (for general and major repair of the vehicle) to be undertaken. When your skill level begins to allow significant savings on performing complex repair procedures yourself, you may consider purchasing special tools.

Routine Maintenance and Minor Repair Tool Set

The list below includes the minimum tools required for routine maintenance and minor vehicle repair procedures. It is recommended to purchase a set of combination wrenches (with an open-end head on one end and a box-end head on the other). Despite the higher cost of such a set compared with a set of ordinary open-end wrenches, the expense is justified, since these wrenches combine the advantages of both types.

- Set of combination wrenches
• (1/4 - 1 in; 6 - 19 mm)
• Adjustable wrench
• Spark plug wrench (with rubber insert)
- Spark plug gap adjusting tool
- Set of feeler gauges
- Brake bleeder wrench
- Screwdrivers:
• Flat-blade (150 mm long and 8 mm in diameter)
• Phillips No. 2 x 6 in (150 mm long)
- Combination pliers
- Hacksaw with set of blades
- Tire pressure gauge
- Grease gun
- Oil drain pan
- Oil filter wrench
- Funnel (medium size)
- Vehicle support stands (2)
- Drain container


If routine maintenance procedures include basic adjustments, a good-quality timing light and a combination tachometer/dwell meter will also be required. Although these tools are part of the special tools list, they are mentioned here because they are absolutely necessary for properly adjusting engine ignition timing, which is part of routine vehicle maintenance.

General and Major Repair Tool Set

These tools are required for any engine repair operations and are offered in addition to the first list. This list includes a complete set of interchangeable socket heads. Despite their considerable cost, a socket set is extremely useful due to its versatility and ease of use, especially when combined with the various types of drives included in the set. It is preferable to use 1/2 in drives (rather than 3/8 in), since although they are more expensive, they can be used with virtually any type of torque wrench (ideally, a good mechanic should have both types of drives available). A cheaper alternative to a socket set is a set of box wrenches.

- Set of interchangeable sockets (including Torx heads) or box wrenches, sized to match the wrenches in the previous list
- Ratchet reversible drive (for use with sockets)
- Breaker bar 250 mm long
- Universal joint (for use with sockets)
- Torque wrench (with drive of the same size as the sockets)
- Round-face hammer, 8 oz (approx. 230 g)
- Soft-faced hammer (plastic or rubber)
- Screwdrivers:
• Flat-blade (150 mm long and approx. 6.5 mm in diameter)
• Flat-blade (heavy-duty No. 2, 8 mm)
• Phillips (No. 3 x 8 in (203 mm))
• Phillips (heavy-duty No. 2)
- Clamping pliers
- Pliers:
• Electrician's (with insulated handles)
• Long-nose pliers
• Snap ring pliers (internal and external)
- Cold chisel, 1/2 in (13 mm)
- Scraper (made from a flattened and sharpened copper tube)
- Scriber
- Center punch
- Fine-tip punches (1.6, 3.2, 4.8 mm)
- Steel rule/straightedge
- Set of Allen keys (for internal hex head fasteners)
- Set of files
- Wire brush (large)
- Second set of support stands
- Floor jack (hydraulic or scissor type)


Another frequently required tool is an electric drill with a 3/8 in (up to 9.5 mm) chuck and a set of good-quality drill bits.

Special Tools

This list includes tools that are quite expensive, not required regularly, or that require following the manufacturer's instructions when used. If your work does not involve frequent performance of complex mechanical operations, purchasing such tools would be a poor investment. It is sensible to buy them jointly with friends or rent them from repair shops.

Only tools that can be found in retail stores or that are produced for distribution to dealerships are included in the list. You will sometimes find references to such special tools in the text of this Manual. Authors usually try to offer an alternative method that avoids the mandatory use of hard-to-obtain tools. If the use of a special tool cannot be avoided and acquiring it is problematic, it is better to entrust the relevant work to a service specialist.

- Valve spring compressor
- Piston ring groove cleaner
- Piston ring compressor
- Piston ring installer
- Compression tester (compressometer)
- Cylinder bore chamfer tool (counterbore)
- Cylinder bore hone
- Cylinder bore gauge
- Micrometer(s) and/or dial caliper
- Hydraulic lifter removal tool
- Ball joint separator
- Universal puller
- Slide hammer screwdriver
- Dial indicator set
- Timing light (inductive pickup)
- Hand vacuum/pressure pump
- Tachometer/dwell meter
- Universal electrical tester
- Lifting tackle
- Brake spring removal/installation tool
- Floor jack

Purchasing Tools

A novice mechanic may be offered several practical tips on purchasing the necessary tools for routine maintenance and vehicle repair procedures. When preparing for routine maintenance or minor repair procedures, it is sensible to buy tools individually. On the other hand, if extensive work is planned, it is simpler and more reliable to buy a complete modern tool kit from a retail store. A kit usually costs somewhat less than individual purchases and often includes a tool box. Later, individual tools, additional sets and a larger tool box may be bought to expand the selection. Gradually building up the tool set spreads out the expenses and helps determine which tools are truly necessary.

Specialty tool stores are the only source for some special tools, but regardless of the source, avoid cheap purchases, especially when choosing screwdrivers and socket heads, as their service life will certainly be short. The costs of replacing and restoring cheap tools will in the end be incomparably higher than the cost of a single purchase of quality goods.

Tool Care and Storage

Good tools are a valuable investment, so it is sensible to keep them clean and always ready for use. After using a tool and before putting it away, always wipe its surface thoroughly with a clean dry rag, removing dirt, grease and metal particles. Never leave tools scattered around the work area. After completing work, carefully check the area under the hood and under the vehicle for forgotten tools.

A tool rack mounted in a convenient place on the garage wall is ideal for storing tools such as screwdrivers, pliers, hammers and similar items. Sets of wrenches and sockets should be stored in metal cases. Measuring tools must be stored in dry, clean places protected from corrosion.

Always pay attention to the condition of the working surfaces of tools. The striking face of a hammer becomes mushroomed during use, and screwdriver tips gradually lose their edge. Take a little time and effort to remove burrs and restore cutting edges using sandpaper or a file. Replace tools that are irreversibly worn or damaged.

With proper care, your tools will serve you faithfully for a very long time.

Workshop Equipment

When discussing tools, one cannot fail to mention workshop equipment. If work more serious than simple maintenance is planned, care should be taken to prepare a suitable work area.

It must be acknowledged that many vehicle owners are forced to remove engines and perform similar work far from a garage or workshop. In any case, however, an important requirement is the presence of a roof or canopy.

Where possible, any disassembly of vehicle system parts should be performed on a clean, flat workbench or a sturdy table of convenient height. The workbench must be equipped with a vise. A vise with jaws opening up to 100 mm and with soft jaw covers is sufficient.

As mentioned above, the work area must have a clean, dry place for storing tools, lubricating and cleaning fluids, fillers, paints and similar materials.
It should be noted that an electric drill is an absolutely essential tool, so the work area must be equipped with a power source for connecting it. Having a drill with a chuck up to 9.5 mm and a set of good-quality drill bits will greatly facilitate many procedures.

Finally, the workplace must always have a sufficient supply of old newspapers and clean, lint-free rags for cleaning the work area, tools and vehicle parts.

Used oil must be taken to recycling centers in sealed containers.

Never perform any work on an unprotected painted surface of the vehicle; use protective fender covers or, at the very least, cover polished surfaces with old blankets.