NOTE: Some repairs require removing sealant residue with a tap. In operations, where necessary, an appropriate indication is given; in this case, it is important to use a tap of the correct diameter and thread.
Some bolts are coated with sealant and, unless otherwise noted, are not reusable. Always install new bolts with the same part number as the old ones. If it is necessary to reject nuts or bolts, this will be indicated in the description of the repair procedure and in the chart of tightening torques. Do not use your own thread sealants as they may not have the required properties. See also section "Bolts protected with anaerobic sealant (encapsulated) ".
If a bolt or nut is being replaced, it must be ensured that the new bolt or nut has a strength index not lower than the one being replaced. Cotter pin nuts must not be loosened to align the cotter pin holes. An exception is the case when this is provided for by the adjustment instruction.
Do not allow oil or grease to enter tapped blind holes. When a bolt or stud is tightened, the oil that has entered the hole is compressed and can lead to the destruction of the housing and give an incorrect torque value.
Always tighten nuts, bolts and screws to the rated torque. In case of damaged or rusty threads, the displayed torque value may be erroneous.
ALWAYS follow the loosening and tightening sequence of bolts and nuts, if such sequence is indicated. Failure to follow the tightening sequence will result in deformation of the parts and looseness of the connection. If an instruction is given to tighten in several stages, this instruction must be followed; do not try to combine different stages, especially those where the tightening is indicated in degrees.
To check the bolt torque or retighten it, loosen it a quarter of a turn and then retighten it to the correct value.
Unless otherwise specified, do not lubricate bolt and nut threads prior to installation.
If the procedure allows for the reuse of bolts or screws, follow these steps:
- Check thread integrity.
- Remove any remaining sealant from the threads.
- Make sure threads are clean and free of oil and grease.
- Apply the specified sealant to the bolt threads.
CAUTION: DO NOT use a wire brush; avoid damaging the thread.
Comments on this article