DETROIT DIESEL 53
2.1.1
Fuel lnjector
powder from the part by drawing it across a clean
accidentally placed on the lapped surfaces
piece of tissue placed on a flat surface and inspect the
located higher up in the spray tip. The slightest
part. Do not lap excessively (refer to the chart on
lapping action on these surfaces can alter the
minimum thickness).
near-perfect fit between the needle valve and
tip.
5. When the part is flat, wash it in cleaning solvent
and dry it with compressed air.
Before reinstalling used injector parts, lap all of the
scaling surfaces indicated by the arrows in Fig. 31. It
is also good practice to lightly lap the sealing surfaces
6. Place the dry part on the second block. After
of new injector parts which may become burred or
applying lapping powder, move the part lightly across
nicked during handring.
the block in a figure eight motion several times to give
it a smooth finish. Do not lap excessively. Again wash
the part in cleaning solvent and dry it with compressed
air.
Lapping Injector Parts
7. Place the dry part on the third block. Do not use
Lap the sealing surfaces indicated in Fig. 31 and the
lapping powder on this block. Keep the part flat and
chart as follows:
move it across the block several times, using the figure
eight motion. Lapping the dry part in this manner
1. Clean the lapping blocks (J 22090) with compressed
gives it the "mirror" finish required for perfect
air. Do not use a cloth or any other material for this
sealing.
purpose.
8. Wash all of the lapped parts in clean fuel oil and
2. Spread a good quality 600 grit dry lapping powder
dry them with compressed air.
on one of the lapping blocks.
3. Place the part to be lapped flat on the block as
shown in Fig. 33 and, using a figure eight motion,
Assemble Injector
move it back and forth across the block. Do not press
on the part, but use just enough pressure to keep the
Use an extremely clean bench to work on and to place
part flat on the block. It is important that the part be
the parts when assembling an injector. Also be sure all
kept flat on the block at all times.
of the injector parts, both new and used, are clean.
4. After each four or five passes, clean the lapping
Study Figs. 34 through 37 for the proper relative
position of the injector parts. then proceed as follows:
ASSEMBLE INJECTOR FILTERS
Always use new filters and gaskets when reassembling
an injector.
1. Insert a new filter, dimple end down, slotted end up,
Fig. 40 - Tightening Injector Nut With Torque
Fig. 39 - Tightening Injector Nut by Hand
Wrench
Page 18
