Doosan G643E - Replacing Engine Gaskets; Thread Repair

G643 (E) Service Manual Chapter 3. Engine Mechanical System 47
Replacing Engine Gaskets
CAU TIO N
Composite type gaskets are used in some areas
of the engine assembly. These gaskets have a
thin metal core. Use caution when removing or
handling composite gaskets to help avoid
personal injury.
Thread Repair
Figure 12-2
Tool Required:

 General purpose thread repair kits are
available commercially.
Damaged threads may be reconditioned by drilling
out, rethreading, and installing a suitable thread
insert.
CAU TIO N
Wear safety glasses to avoid eye damage.
Figure 12-2 Repairing Thread Holes
1. Determine size, pitch, and depth of damaged
thread. If necessary, adjust stop collars on
cutting tool and tap to required depth.
IMPORTANT: Refer to the kit manufacturer's
instructions regarding the size of drill and tap to
be used.
2. Drill out damaged thread.
3. Tap hole. Lubricate tap with light engine oil.
Clean the thread.
IMPORTANT: Avoid build-up of chips. Back out
the tap every few turns and remove chips.
4. Thread the thread insert onto the mandrel of the
installer. Engage the tang of the insert on the
end of the mandrel.
5. Lubricate the insert with light engine oil (except
when installing in aluminum) and install.
IMPORTANT: When correctly installed, the insert
should be flush to one turn below the surface.
6. If the tang of the insert does not break off when
backing out the installer, break the tang off with a
drift.