Checking Injection Nozzles
Checking injection nozzlesTest Values:
Tightening torques
Injection nozzle upper and lower half 70-80
Special And Conventional Tools:
Note
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.
Attention!
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 (13) is pressed into top of injection nozzle holder (7).
Testing
1 Remove injection nozzles. Removal and Installation of Injection Nozzles
2 Connect removed injection nozzle to tester. With pressure gauge switched off, plunge down energetical ly 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 welt. Individual drops, diagonal or diagonally broken jets, slightly wide jets are of no significance for combustion in engine.
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-like jet (arrow) should come out of longitudinal bore (15). If no cord-like jet comes out, check longitudinal bore with cleaning needle 0.13 mm dia for unobstructed passage. If the longitudinal bore is clear, the injection nozzle can be used again.
Note: Test procedure also applies to new injection nozzles.
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 dis tinctively. Set injection nozzle to specified ejection pressure (opening pressure), if required (O7.1~137).
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. In the event of leaks, disassemble injection nozzle, clean, assemble and adjust. Disassembly, Cleaning, Assembly and Adjustment of Injectors