How Not to Build a Cummins Celect™ Injector

• Use the nozzle over and then ignore the fuel flow:  The holes in a nozzle erode over time, and the seat needle tip area is subject to some extremely high stresses and temperature.  While a remanufactured nozzle may have good chatter characteristics, it may not have the correct fuel flow characteristics and/or it may have excessive needle valve lift.  Nozzle fuel flows are one of the most critical parts of a Celect injector.  We hydraulically flow all nozzles to insure that fuel flows under pressure are correct prior to assembly into an injector.  If a re-manufactured nozzle flows outside of specification due to hole erosion and/or excessive needle valve lift we send it to the scrap, and replace it with a new one.
• Assume that the nozzle that was in the injector is correct:  It seems most Celect injector rebuilders assume that no one ever makes a mistake!   The nozzle that came out of the injector must be the correct one, and the same nozzle or a replacement nozzle of the same part number will be correct.  We have lost count of how many mismatched nozzles we have seen in Celect injectors.  We check each and every nozzle, and a nozzle is NEVER simply used over.  We have 100% nozzle replacement with remanufactured or new.
• If the pressure spring is not broken, use it over:  The nozzle pressure spring is one of the most common failure areas in the Celect injector.  This is also a very complex spring since it is very small and operates in an extreme environment.  We replace 100% of these springs with new.
• Excessively worn spring cages can be machined down to remove the wear areas:  Worn nozzle spring cages create excessive needle valve lift.  Excessive needle valve lift results in high fuel flows at lower engine speeds.  If a nozzle spring cage is not perfectly flat and within .0005" of the proper height it will cause problems.  We would rather be safe than sorry, and we replace any of these outside of these specifications with a new one!  Currently we replace over 80% with new!  We have seen many Recon™ injectors "out of the box" with what we feel are worn out spring cages!
• A worn spring guide can be reused as long as the opening pressure is ok:  This innocent looking part is the cause of many nozzle related failures.  We replace every nozzle spring guide with a new one!. 
• Opening pressure is not critical, and plus or minus 300 PSI is ok:  Although nozzle opening pressure may not be critical at higher engine speeds, it does have an effect on idle quality, starting ability as well as engine performance during the initial warm-up.  We set all nozzle opening pressures at plus/minus 150 PSI.   This takes a little more time, but it helps to produce a better and more consistent injector.
• Ceramic check balls do not wear, and can be used over or replaced with a steel check ball:  This injector contains a ceramic check ball for a reason.  The ceramic check balls are more reliable than steel ones, and since they are considerably lighter they also react to pressure changes faster.  There are a lot of things going on at the same time in this injector, and time and/or check valve leakage can be critical in the operation of the injector.  We test all check balls as well as the check ball seat for leakage prior to assembly.
• There is no need to disassemble the check valve cage, as there is nothing that can go wrong with it:  The valve in this cage needs to seal for every single injection.  We test both the valve and the valve seat prior to assembly.  Any cages that leak are replaced with remanufactured ones.
• The metering barrel and plunger can always be used over:  We have seen very few aftermarket injectors that have had the plunger and/or the barrel and plunger assembly replaced.   This assembly is very critical to the injector fuel flows, and the resulting fuel economy of the engine.  We have seen many creative attempts to salvage this part including replacing ceramic plungers with steel ones.  Cummins uses a ceramic plunger for good reason, and for injector applications that require then (this means almost every injector) we replace these with an assembly that includes a ceramic plunger!
• Ceramic plungers do not wear out, and will always be ok to use over:  Not so.  Although wear on a ceramic plunger is minimal, the barrel and especially the charge ports are still subject to cavitations and erosion.  As noted above, this will affect the fuel flows and the ultimate life of the injector.  We find that most ceramic plunger injectors have worn out barrels and we then replace the entire plunger/barrel assembly with a new one!
• OE style installation o-rings are too expensive and not really required.  A standard Viton o-ring is just as good:  The Celect injector is subject to some extreme temperatures when installed in the engine.  Why some rebuilders choose to save fifty cents by using standard o-rings is beyond us, but this is something we see on a regular basis.  We use OEM or equivalent seals for the entire injector.
• Since the control valve assembly is very difficult to repair,  use it over as long as it does not leak more than a little:  We could write a book about this control valve.  It is possibly the most critical part of the injector, and also the most difficult part to repair/remanufacture properly.  We have a zero tolerance for leaky control valves, and each one is remanufactured back to original dimensions.  We have seen more injector failures due to this control valve than any other part in the injector.  The remanufactured injector is only ever going to be as good as the quality and effort put into the control valve!
• Most wiring harnesses can be used over:  Bad connections, bare wires, broken caps are some of the things we see on a regular basis.  If we cannot restore a harness to "like new" condition, we replace it with a new one!  Nothing is more frustrating than a failure caused by bad connections, and they can be very difficult to diagnose.
• The upper pumping plunger never wears and can always be used over:  Failures in this area are few, but when fuel contamination has been an issue, then failures in this area are not that un-common.  We test all body/plunger assemblies and replace any that leak with remanufactured ones.
• Body plugs do not have to be replaced:  The body plugs are a common source of 'fuel in oil' complaints.  It is a minor detail, but we replace all body plugs and gaskets with new.

Yes, we agree with the OEM that this is a very difficult injector to repair properly, but with disagree with their claim that only they can do it!  We know that we can produce an injector with the same quality as theirs, at a price that is competitive and fair!