Repairing Damaged Threads
Occasionally, threads are stripped through care-
lessness or impact damage. Often the threads can be
repaired by running a tap (for internal threads on
nuts) or die (for external threads on bolts) through
the threads (
Figure 42
). To clean or repair spark
plug threads, use a spark plug tap.
If an internal thread is damaged, it may be neces-
sary to install a Helicoil or some other type of thread
insert. Follow the manufacturer’s instructions when
installing their insert.
If it is necessary to drill and tap a hole, refer to
Table 9
for metric tap and drill sizes.
Stud Removal/Installation
A stud removal tool is available from most tool sup-
pliers. This tool makes the removal and installation of
studs easier. If one is not available, thread two nuts
onto the stud and tighten them against each other. Re-
move the stud by turning the lower nut (
Figure 43
).
1. Measure the height of the stud above the surface.
2. Thread the stud removal tool onto the stud and
tighten it, or thread two nuts onto the stud.
3. Remove the stud by turning the stud remover or
the lower nut.
4. Remove any threadlocking compound from the
threaded hole. Clean the threads with an aerosol
parts cleaner.
5. Install the stud removal tool onto the new stud or
thread two nuts onto the stud.
6. Apply threadlocking compound to the threads of
the stud.
7. Install the stud and tighten it with the stud re-
moval tool or the top nut.
8. Install the stud to the height noted in Step 1 or
torque it to specification.
9. Remove the stud removal tool or the two nuts.
Removing Hoses
When removing stubborn hoses, do not exert ex-
cessive force on the hose or fitting. Remove the
hose clamp and carefully insert a small screwdriver
or pick tool between the fitting and hose. Apply a
spray lubricant under the hose and carefully twist
the hose off the fitting. Use a wire brush to clean
any corrosion or rubber hose material from the fit-
ting. Clean the inside of the hose thoroughly. Do not
use any lubricant when installing the hose (new or
old). The lubricant may allow the hose to come off
the fitting even with the clamp secure.
Bearings
Bearings are used in the engine and transmission
assembly to reduce power loss, heat and noise re-
22
CHAPTER ONE
41
REMOVING BROKEN
SCREWS AND BOLTS
1. Center punch broken stud
2. Drill hole in stud
3. Tap in screw extractor
4. Remove broken stud
42
Tap
Die