Testing Air Tightness - Kohler KD 425-2 Workshop Manual

XI
INJECTION EQUIPMENT
42
43
44
45
- 28 -
The difference between the deliveries of the two pumps
when locked must not exceed 0.5 cc.
Also check:
1. That the distance between the injection cams in the rest position
(bottom dead centre) and the pump supporting face is between
52.8 and 54.4 mm as shown on the data plate;
2. That the stroke of the piston with injection cams in the rest po-
sition (bottom dead centre), to the start of delivery is between 2
and 2.1 mm.
Assembly of injection pumps
If it proves necessary to disassemble the injection pumps they must
be reassembled following the instructions listed below:
1. Insert barrel into pump casing with the fuel inlet hole aligned with
the feeding connection (fig.42). This is the only possible position
because of the stud on the pump body. Make sure that the sea-
ting face between the barrel and the pump are free of dirt.
2. Insert delivery valve, copper gasket, spring, washer, filler, O-ring,
and temporarily tighten the delivery connection.
3. Insert plunger, with helical profile (A, fig.43) on the opposite side
of the sleeve pin (B, fig.43), into the internal groove of the control
sleeve (make sure the helical profile is turned towards the fuel
inlet and eccentric pin (C, fig.43).
4. Complete pump assembly with plunger (a, fig.44), control sleeve
(b), upper washer (c), retaining ring (d), spring (f) and secure all
with the spring holder washer (g)
5. Tighten delivery valve holder (h, fig.44) to 4.5 ÷ 5 kgm torque.
6. Check, by compressing the spring through its various work posi-
tions, that the control sleeve (b, fig.44) turns freely and does not
stick or encounter resistance throughout its full stroke; any irregu-
lar movement will give rise to hunting of engine speeds.
7. Secure the control sleeve using the pin (n, fig.44) screwed into
pump housing.
Always check the injection pump calibration after the deli-
very connection (h, fig.44) has been dismantled.

Testing air tightness

Feed pressurized air at 6 Kg/cm² into the fuel sullpy union and com-
pletely immerse the pump in oil or diesel fuel for about 20 ÷ 30 secon-
ds (fig.45); check that no air bubbles are released.
N.B.: Tightness can be checked by compressing the springs to
52.8 ÷ 54.4 mm, which corresponds to the bottom dead centre wor-
king position of the pump.
KD 425-2 Workshop Manual_cod. ED0053029360_1° ed_ rev. 00