You have the hard part done then. If you have access to a bench vice, take the injector apart. It comes apart in halves. Upper half will have the shim, spring, and tappet. Lower half will have the sealing disk and the nozzle/pintle assembly.
Soak the whole thing in solvent and make sure it is VERY clean. Use a piece of glass (I use a piece from a picture frame) and lay down a sheet of 2000 or 4000 grit sandpaper. Dribble on some diesel fuel for lubricant and polish the face of the upper half of the injector holder, both faces of the sealing disk, and the upper face of the injector nozzle (the part that seals against the sealing disk). Clean everything very well in clean solvent. Pull out and let dry, then drop everything into clean diesel fuel.
Hold the upper half of the injector holder upside down (so the part the hard line screws into is pointing at the floor). Drop in your shim(s), spring, and tappet. Lay on the sealing disk, then lay down the new nozzle (or your cleaned old one) and thread on the lower injector half by hand. Clamp in a vice upside down and torque to 70NM.
Now go out and test your pop pressure. If it isn't where you want it, disassemble and add or remove shims above the spring. Reassemble and re-test. You don't need to re-polish the sealing parts when doing this.
Once your pop pressure is where you want it, check the spray pattern. It should have a nice even cone. You shouldn't see one side spraying heavier than the other, spraying off to one side, or spraying in a straight/squirt-gun pattern.
If the pattern is good, move on to chatter. Give long constant strokes just at the pop pressure. The injector should be pulsing on and off as you pump the lever. If you go too fast, you'll get a constant spray. If you time it just right, you'll get it to "sing", sort of a very high pitched whine as the injector rapidly pops. If the injector doesn't chatter, or if it pops and continues to spray without resetting, it likely is binding up in its bore.
Assuming the chatter was good, slowly build pressure in the pop tester until you get just to the pop pressure. Hold that pressure with the lever and check the tip. If it starts to "pee" you likely need to disassemble the injector and clean the holder. Sometimes they will just barely weep, then pop. That's fine. This is a mechanical device, they aren't perfect.
Relieve pressure, then pump up ~15-20bar below your pop pressure and maintain that pressure. On a turbo engine, that's ~1600PSI. Count to 10. You should have no drops coming off the tip of the injector.
Last test. Make sure the relief valve is firmly tightened on your pop tester, then pump the lever until the injector pops, then allow pressure to naturally decay. If it drops below 1600PSI in ~10 seconds, the internal leakage is high. You'll need to re-polish the mating surfaces and try again.
Spend your time up front getting the pop pressure dialed in, then worry about the functional parts later. You'll save a ton of time. The process isn't difficult, just time consuming. An anal attention to detail matters. You'll have a decent running and reasonably smooth idling engine if you get the pop pressures +/-50PSI (100PSI between lowest and highest pop) by adjusting shims. You'll get the best results by getting it +/-25PSI (50PSI between lowest and highest pop). The pop pressure influences injection timing, the tighter the tolerance, the tighter the timing will be. This isn't a perfect world, so don't dwell on perfection. 50PSI spread is fine, 25 is better. If you have compression imbalance, you won't notice the 25PSI difference anyway, so use your time wisely!
Soak the whole thing in solvent and make sure it is VERY clean. Use a piece of glass (I use a piece from a picture frame) and lay down a sheet of 2000 or 4000 grit sandpaper. Dribble on some diesel fuel for lubricant and polish the face of the upper half of the injector holder, both faces of the sealing disk, and the upper face of the injector nozzle (the part that seals against the sealing disk). Clean everything very well in clean solvent. Pull out and let dry, then drop everything into clean diesel fuel.
Hold the upper half of the injector holder upside down (so the part the hard line screws into is pointing at the floor). Drop in your shim(s), spring, and tappet. Lay on the sealing disk, then lay down the new nozzle (or your cleaned old one) and thread on the lower injector half by hand. Clamp in a vice upside down and torque to 70NM.
Now go out and test your pop pressure. If it isn't where you want it, disassemble and add or remove shims above the spring. Reassemble and re-test. You don't need to re-polish the sealing parts when doing this.
Once your pop pressure is where you want it, check the spray pattern. It should have a nice even cone. You shouldn't see one side spraying heavier than the other, spraying off to one side, or spraying in a straight/squirt-gun pattern.
If the pattern is good, move on to chatter. Give long constant strokes just at the pop pressure. The injector should be pulsing on and off as you pump the lever. If you go too fast, you'll get a constant spray. If you time it just right, you'll get it to "sing", sort of a very high pitched whine as the injector rapidly pops. If the injector doesn't chatter, or if it pops and continues to spray without resetting, it likely is binding up in its bore.
Assuming the chatter was good, slowly build pressure in the pop tester until you get just to the pop pressure. Hold that pressure with the lever and check the tip. If it starts to "pee" you likely need to disassemble the injector and clean the holder. Sometimes they will just barely weep, then pop. That's fine. This is a mechanical device, they aren't perfect.
Relieve pressure, then pump up ~15-20bar below your pop pressure and maintain that pressure. On a turbo engine, that's ~1600PSI. Count to 10. You should have no drops coming off the tip of the injector.
Last test. Make sure the relief valve is firmly tightened on your pop tester, then pump the lever until the injector pops, then allow pressure to naturally decay. If it drops below 1600PSI in ~10 seconds, the internal leakage is high. You'll need to re-polish the mating surfaces and try again.
Spend your time up front getting the pop pressure dialed in, then worry about the functional parts later. You'll save a ton of time. The process isn't difficult, just time consuming. An anal attention to detail matters. You'll have a decent running and reasonably smooth idling engine if you get the pop pressures +/-50PSI (100PSI between lowest and highest pop) by adjusting shims. You'll get the best results by getting it +/-25PSI (50PSI between lowest and highest pop). The pop pressure influences injection timing, the tighter the tolerance, the tighter the timing will be. This isn't a perfect world, so don't dwell on perfection. 50PSI spread is fine, 25 is better. If you have compression imbalance, you won't notice the 25PSI difference anyway, so use your time wisely!
__________________
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'86 300SDL - "The Diseasel" 175K
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The Diseasel Thread - Everything You Didn't Know You Wanted To Know
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Posted by: Nate <vwnate1@yahoo.com>
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