DETROIT DIESEL 53
Fuel Injector 2.1.1
The exterior surface of an injector spray tip may be cleaned by using a brass wire buffing wheel, tool J 7944. To obtain a
good polishing effect and longer brush life, the buffing wheel should be installed on a motor that turns the wheel at
approximately 3000 rpm. A convenient method of holding the spray tip while cleaning and polishing is to place the tip
over the drill end of the spray tip cleaner tool J 1243 and hold the body of the tip against the buffing wheel. In this way,
the spray tip is rotated while being buffed.
CAUTION: Do not buff excessively. Do not use a steel wire buffing wheel or the spray tip
holes may be distorted.
When the body of the spray tip is clean, lightly buff the tip end in the same manner. This cleans the spray tip orifice area
and will not plug the orifices.
Wash the spray tip in clean fuel oil and dry it with compressed air.
Clean and brush all of the passages in the injector body, using fuel hole cleaning brush J 8152 and rack hole cleaning
brush J 8150. Blow out the passages and dry them with compressed air.
Carefully insert reamer J 21089 in the injector body (Fig. 29). Turn it in a clockwise direction a few turns, then remove the
reamer and check the face of the ring for reamer contact over the entire face of the ring. If necessary, repeat the
reaming procedure until the reamer does make contact with the entire face of the ring. Clean up the opposite side of the
ring in the same manner.
Carefully insert a .375" diameter straight fluted reamer inside the ring bore in the injector body. Turn the reamer in a
clockwise direction and remove any burrs inside the ring bore. Then wash the injector body in clean fuel oil and dry it with
Carefully insert carbon remover tool J 9418-1 in the injector nut. Turn it in a clockwise direction to remove the carbon
deposits on the flat spray tip seat as shown in Fig. 30. Remove the carbon deposits from the lower end of the injector nut
with carbon remover J 9418-5 (Fig. 30) in the same manner. Use care to prevent removing any metal or setting up burrs
on the spray tip seat.
Wash the injector nut in clean fuel oil and dry it with compressed air. Carbon deposits on the spray tip seating surfaces of
the injector nut will result in poor sealing and consequent fuel leakage around the spray tip.
When handling the injector plunger, do not touch the finished plunger surfaces with your fingers. Wash the plunger and
bushing with clean fuel oil and dry them with compressed air. Be sure the high pressure bleed hole in the side of the
bushing is not plugged. If this hole is plugged, fuel leakage will occur at the upper end of the bushing where it will drain
out of the injector body vent and rack holes, during engine operation, causing a serious oil dilution problem. Keep the
plunger and bushing together as they are mated parts.
After washing, submerge the parts in a clean receptacle containing clean fuel oil. Keep the parts of each injector
Inspect Injector Parts
Inspect the teeth on the control rack and the control rack gear for excessive wear or damage. Also check for excessive
wear in the bore of the gear and inspect the gear retainer. Replace damaged or worn parts.
Inspect the injector follower and pin for wear. Refer to Section 2.0.
FIG. 34. Location of Filter In Injector
Fig. 33. Lapping Spray Tip on
Lapping Blocks J 22090