General tips for carrying out repairs (BMW 3 Series E46)

When servicing, restoring or repairing your vehicle's systems, please follow these rules to ensure that you complete the job successfully and at a high professional level.

Mating surfaces and gaskets

When disassembling mating parts, never insert screwdrivers or similar tools between them. This may cause serious damage, which after assembly causes leakage of oil, coolant, etc.

Separation is usually accomplished by tapping along the mating surfaces with a soft mallet to dislodge or break the gasket. However, this method is not suitable for disassembling pinned joints.

If there is a gasket required between the mating surfaces of two parts, always replace it with a new one during assembly; install a dry gasket unless the assembly manual specifies otherwise.

Before installation, ensure that the mating surfaces are clean and dry and free of any old gasket residue. When cleaning the mating surfaces, use a tool that will not damage the surface and remove any burrs or nicks with an oiled abrasive block or a fine file.

Make sure all threaded holes are clean and do not allow liquid sealant to enter them unless otherwise specified in the assembly manual.

Make sure all holes, channels or pipes are clean, blow them out with compressed air.

Sealing cuffs

The cuff can be removed by prying it up with a flat-head screwdriver or similar tool. Alternatively, you can screw several self-tapping screws into the cuff and pull the cuff out using them with pliers.

In any case and regardless of the reason for removal, the removed cuff should be replaced with a new one upon installation.



The thin edge of a new seal can be easily damaged and will not perform its function if scratches, nicks or grooves are not completely removed from the surface with which it contacts. If the surface of the part cannot be restored and the manufacturer has not provided for some movement of the seal relative to the surface, the part must be replaced.

Keep the working edges of the seal from contact with any parts that may damage them during installation. If possible, use tape or a conical mandrel. Lubricate the seal with oil before installation. When installing a seal with two edges, fill the space between them with consistent grease.

Unless otherwise specified, seals must be lubricated with the oil they are intended to prevent leakage when installed.

To press the cuff into the housing, use a ring mandrel of the appropriate size or a wooden block. The cuff should be installed flush with the housing surface (unless otherwise stated).

Threaded connections

Seizures when loosening nuts, bolts and screws are usually caused by corrosion. If a threaded connection does not loosen, wet the place of such a connection with liquid oil, kerosene or another similar liquid and hold it for some time. To loosen tight connections, tap on the lever connected to the screwdriver or the head of the key. If none of these methods help, you can try to carefully heat the connection. The last resort is to use a hacksaw or chisel.

Studs are usually removed in the following manner. Screw two nuts onto the stud and tighten them well together. Then, using a wrench, turn the bottom nut to loosen the stud. Studs or bolts that have broken below the surface of the part into which they were screwed can sometimes be removed with a stud extractor. Before screwing a stud or bolt into a blind hole, first make sure the hole is completely clear of fluid (oils, fats, water, etc.). If this is not done, the housing may be destroyed due to the increased hydraulic pressure that the bolt or stud creates when screwed in.



When tightening a castle nut, tighten the nut to the specified torque, then tighten it to the next cotter pin hole. Never loosen the nut to align the cotter pin holes unless specifically stated in the assembly instructions.

If you need to check that the bolt or nut is properly tightened, unscrew it (it) by a quarter turn, then tighten it again to the required torque using a torque wrench. However, this cannot be done if the connection has been rotated to the required angle after tightening with a torque wrench.

For some threaded connections, especially for cylinder head bolts or nuts, the final tightening stage is not specified by torque, but by the angle by which the fastener must be turned. Usually, a fairly low torque is specified for tightening bolts in a certain sequence, and then the turn is made in one or more steps by the specified angles.

Washers, locknuts, locking elements

Any fastener that requires rotation relative to a component or housing when tightened must always have a washer installed between it and the component in question.

Spring or split washers in critical joints such as the big-end connection should always be replaced. Bend-off washers should also always be replaced if they have been bent back even once to free a nut or bolt.

Self-locking nuts can be used repeatedly in less critical connections, provided that resistance is felt when tightening, when the locking part of the nut enters the thread of the stud or bolt. However, with prolonged use, self-locking nuts gradually lose their effectiveness and they also need to be replaced periodically.



Cotter pins should always be replaced with new ones that match the size of the hole.

If anaerobic sealant or other anti-loosening compound has been applied to the threads, it should be washed off with solvent and a wire brush, and fresh compound should be applied during assembly.

Special tools and devices

Some repair procedures described in this manual require the use of special tools and devices such as a press, two- or three-jaw pullers, spring compressors, etc. Wherever possible, suitable substitutes for the special tools are indicated. In some cases, where other options are not possible, it is necessary to use the original tool for safety and quality reasons. If you are not highly qualified or if you do not understand everything in the description of the procedures, never try to do without the use of a special tool (devices), when the procedure described involves its use. In this case, you risk not only getting injured, but also damaging expensive parts.

Environmental protection

When changing oils, brake fluid, antifreeze, etc., it is necessary to take measures against environmental pollution. Never pour any of the above-mentioned liquids into the general sewer or on the ground, where they can be absorbed. There are many collection points for used oils and other liquids. Each garage or guarded parking lot should have a special collection point for such liquids.

Due to the ever-increasing tightening of environmental legislation, in particular, the reduction of air pollution by motor vehicles, many cars have devices protecting the most important places of fuel system adjustment. These protective devices are intended primarily to prevent unqualified interference in the adjustment of air-fuel mixtures, which can cause an increase in the toxicity of exhaust gases. Such means of protection must be restored after repair, in accordance with the requirements of the manufacturer or current legislation.

Remember: It is immoral and illegal to pour oil down the drain. Find a local used oil collection point.