CRD - Fuel Injector Seal or Fuel Injector issue? -
  • 1 Post By underscore
  • 1 Post By Tetto
  • 1 Post By Chirpz
  • 1 Post By TurboDiesel
  • 1 Post By sampuppy1
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post #1 of 7 Old 04-14-2018, 06:02 PM Thread Starter
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CRD - Fuel Injector Seal or Fuel Injector issue?

I'm having a discussion with my dad. I have researched some information about my issue with the fuel injector and I've come to the conclusion that the seal needs replacement; black tar caked around the port hole. He's asking me how I know it's not the whole injector that needs replacing. I'm at a loss for words on the matter. How DO I know not to just replace the whole thing? Would I have a code?

Currently it looks like the middle injector on the left side is leaking. It's easy to see and hopefully it's my only issue. But I'm curious; how does one diagnose a failing injector vs a leaking one?

Will fixing it stop my issues with chugging cold start / intermittent chugging on warm days? Or does that still sound like a glow plug issue? I'm not sure how much both issue symptoms overlap.


2008 Jeep Grand Cherokee CRD
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post #2 of 7 Old 04-14-2018, 09:37 PM
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From reading on the one parts site (the name eludes my memory at the moment) the injector seals are considered a wear item expected every ~100k miles. Also the parts are cheap, so I'd try that before replacing an injector if the only symptom is leaking.

I guess you could flip the question back on him, what makes him think a leak indicates an injector is failed?
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post #3 of 7 Old 04-14-2018, 10:24 PM
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Fuel will leak if you have a bad seal, regardless of a good or bad injector.

As far as I know, the only way to test for a malfunctioning injector is a leak test (aside from observing related symptoms, of course).
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post #4 of 7 Old 04-14-2018, 11:57 PM
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Oh man! Don't replace the injector yet. It sounds like you have a bad seal for sure and you may have glow plug issues too.

Here is a Step by Step DIY to repair the injector seal....

and in PDF format, click this link

or you can read the whole thread here:

Fix the seal and clean up the mess. It will sound better and the smell with go away eventually. Then deal with the glow plugs.
A bad glow plug or bad plug module will usually throw a code and may cause difficult starting. If you have no glow plug codes... Its probably not a plug or modulator. If you DO have a bad plug, it may cause difficulty starting, but after the engine is running it will not cause chugging.

It is possible to have a bad injector and that would probably cause chugging but its cheap and pretty easy to change the why not try it. Bad seals are very common....bad injectors are way less common.... they are also expensive.
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post #5 of 7 Old 04-16-2018, 04:50 PM
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as everyone said, just fix the seal and replace the bolt aswell

my jeep used to chug all the time when starting and when i did my oil cooler leak fixed i got all my glow plugs changed out and its never chugged since, even in the middle of winter
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post #6 of 7 Old 04-19-2018, 09:37 PM
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The black death is a typical symptom of a failed injector seal. I just recently went through this on the wife's WK.

An injector leak test as stated above is really the only way to test for a failing injector. The black death would not be due to an injector failure unless the body itself was broken/cracked which is possible.....but highly unlikely. The parts for the seal are cheap. I'd pick up 6 seals, 6 return line O rings and 6 bolts. I have pics and part numbers listed in Chirpz's thread.

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post #7 of 7 Old 04-21-2018, 04:45 PM Thread Starter
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Thanks everyone. I already predicted these issues and have a full 6 glow plugs and will order some seals for injectors to follow. May be a big project for one day.

My fuel economy is suffering greatly in the mean time. I have used Royal Purple atomizer fuel injector cleaner as a preemptive treatment so it might clean them as well as they can from the inside before taking the suspect ones out for seals.

2008 Jeep Grand Cherokee CRD
GDE Hot Tune, DPF Delete, Turbo Res. Delete, Exhaust Res. Delete
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