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OM 617 – Checking injection nozzles

Use only clean testing oil or filtered diesel fuel for testing. When testing a nozzle, never move hand into
jet of a nozzle. Jet will deeply enter flesh and will destroy the tissue. Fuel entering into blood may cause blood poisoning.

The shutoff valve of pressure gauge should remain closed during jet and buzzing test, since otherwise
the pressure gauge may be damaged by excessive pressure increase.

The injection nozzle with Bosch designation DN 0 SD 240 is a perforated pintle nozzle. This nozzle
differs from the pintle nozzle by a crosswise and lengthwise bore (14 and 15) in throttle pintle. In
addition, a maintenance-free rod-type filter (1 3) is pressed into top of injection nozzle holder (7).

1. Remove injection nozzles (07.1-230).
2. Connect removed injection nozzle to tester. With pressure gauge switched off, plunge down energetically several times. With a perfectly moving nozzle needle nozzle should buzz together with a high whistling sound.

3. Jet test with shutoff valve closed. Insert injection nozzle into tester. At short, fast partial strokes
(approx. 2 strokes per second) the jet should be rather concentrated and should break well. l ndividual
drops, diagonal or diagonally broken jets, slightly wide jets are of no significance for combustion in engine.

A. Good injection nozzle
Jet concentrated and well atomized
B. Damaged injection nozzle
Jet too wide, streaky and not concentrated

4. Test longitudinal bore (15) in throttle pintle. At slow, uniform downward movement of hand lever
(approx. 4-6 seconds per stroke) a distinct, vertical cord-li ke jet (arrow) should come out of longitudinal bore (1 5). If no cord-like jet comes out, check longitudinal bore with cleaning needle 0.13 mm dia for unobstructed passage. I f the longitudinal bore is clear, the injection nozzle can be used again.
Note: Test procedure also applies to new injection nozzles.

14. Crosswise bore
15. Lengthwise bore

5. Buzzing test. Push hand lever slowly fully down (approx. 1 stroke per second); a damped buzzing of
injection nozzle should be heard.
If the jet or the buzzing test are not in order, flush injection nozzle by means of several short, fast full
strokes ( 2 strokes per second). The jet should be concentrated and emerge with a clearly heard, high
whistling sound. Replace injection nozzle if required.

6. Test opening pressure of injection nozzle.
Slowly push hand lever down (1 stroke per second) with shutoff valve open. When ejection begins, read
ejection pressure; injection nozzle should buzz distinctively. Set injection nozzle to specified ejection
pressure (opening pressure), if required (07.1 -1 37).

7. Check injection nozzle for leaks.
With shutoff valve open, slowly push pump lever down up to ejection pressure. Release pump lever, ejection pressure should remain constant. I n the event of leaks, disassemble injection nozzle, clean, assemble and adjust (07.1-137).


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