Usage:
3406 Truck Engines Equipped With New Scroll Fuel System (NSFS)
This article provides information for a new chemical cleaning process for the fuel injection pump bonnet and barrel sealing surfaces. Either chemical cleaning or lapping may be used to recondition the barrel sealing surfaces. Laboratory and field testing have shown the chemical cleaning process is less subjective and results in better sealing than the hand lapped parts.
Before beginning the Sealing Face Chemical Cleaning Process, do the Precleaning Inspection. Replace 2W-2409 and 6I-1665 Bonnets with new 108-2102 Bonnets.
Precleaning Inspection
Illustration 1. Top View Of Barrel
A. Do not reuse if the check valve seating surface is nicked.
B. Staining here is acceptable. The new bonnet seal ring is inside this diameter. There is no need to remove light to moderate stains in this area.
Illustration 2. Plunger
NOTE: Do NOT mix plungers and barrels. The original plungers must remain with the same barrels. If the plunger is not acceptable, a new pump group is required. Do not proceed with this process if the plunger is not acceptable.
C. Cavitation erosion above the scroll edge is acceptable.
D. Plungers with worn or nicked scroll edges should not be reused.
Illustration 3. Top View Of Barrel
E. A mirror image of the check valve notch is acceptable.
F. Heavy staining should be removed to prevent debris from getting into the sealing joint during assembly. Visible staining "Not Easily Removed" is acceptable because the new bonnet seal ring is inside this diameter.
Illustration 4. Bottom View Of Bonnet (Left). Top View Of Barrel (Right)
G. This style bonnet can have staining removed with the same cleaning process and reused.
H. Multiple relief notches are acceptable.
J. Light staining and fretting is not an automatic indication of joint leakage. This should be cleaned before reuse.
Illustration 5. Top View Of Barrel
K. Staining and/or fretting "Before" cleaning.
Illustration 6. Top View Of Barrel
L. A 7000 Series nozzle tip cap in the barrel bore will help keep the cleaning fluid on the surface. Remove the cap and flush the barrel with clean diesel fuel after cleaning. The chemical cleaning will remove surface stains, but fretting will remain. Laboratory and field test indicate a new style bonnet combined with increased bushing tightening torque [300 N·m (220 lb ft)] will seal with a fretted barrel.
NOTE: The bushing tightening torque of 300 N·m (220 lb ft) is for used plungers and barrels with face fretting ONLY. Use the standard bushing tightening torque of 260 N·m (190 lb ft) in all other cases.
Illustration 7. Timing Spacer
M. Debris dent in a timing spacer. Do not reuse. Manufacturing grind marks are acceptable and lapping is not required.
Illustration 8. Bushing
N. Do not reuse bushings with heavy amounts of spline rust. The splines must be in good condition to maintain the tightening torque. Number the bushings as they are removed so they can reinstalled in the same bores.
Sealing Face Chemical Cleaning Process
1. Obtain a container of 1U-9698 Descaleant
2. Provide a clean work area.
NOTE: Do NOT mix plungers and barrels. The original plungers must remain with the same barrels.
3. Use a clean soft cloth to wipe the sealing faces of the barrel and bonnet as clean as possible.
4. Plug the barrel and bonnet bores with a non-damaging material. A 7000 Series nozzle tip cap will fit in the bores. See Illustration 6.
5. Use the 1U-9698 Descaleant and a cotton swab to scrub the stained sealing surfaces of the bonnet and barrel.
6. Let the descaleant remain on the sealing surfaces for between two minutes (minimum) and five minutes (maximum).
7. Use a cotton swab to repeat the scrubbing action. Then flush the sealing surfaces with clean diesel fuel.
8. Assemble the fuel injection pump groups using the original plungers.
9. Visually inspect the timing spacers (Illustration 7) and bushings (Illustration 8).
10. Install the fuel injection pump groups into a clean fuel injection pump housing. Reuse the timing spacers and bushings. Use new seals. Lubricate the new seals with clean diesel fuel.
11. If the new bushings are NOT required, tighten the bushings to a torque of 300 N·m (220 lb ft). If a new bushing is used:
a. Tighten the bushing to a torque of 300 N·m (220 lb ft).
b. Loosen the bushing 1/4to 1/2turn.
c. Tighten the bushing to a torque of 300 N·m (220 lb ft).
NOTE: The bushing tightening torque of 300 N·m (220 lb ft) is for used plungers and barrels with face fretting ONLY. Use the standard bushing tightening torque of 260 N·m (190 lb ft) in all other cases.
Check the rack for free movement after each bushing is tightened.