Diagnosing #4 leak and/or injector failure.

Gypsy62 · **Posted:** Tue May 04, 2021 3:37 pm

More fun.
Been driving with a 'damp' #4 injector area for about 3k miles, and averaging 18mpg. Unsurprisingly, damp is now 'wet', and I'm getting 13mpg!

With engine running at idle the leak is not visibly flowing. It def is not at the fuel line from rail. The return T seems solid; all replaced less than <10k miles, same with return lines.

CEL: 1 only; 0299 = Turbo under/overboost (persistent since Garrett install...).

I just stethoscoped atop the securing claw at the base of all 4 injectors. All four sound 'consistent', with no arythmic or anamolous weird chatter. Otherwise, very curious what folks make of the chatter-variation across the injectors. All at idle, 750revs:
- #1 & 3 sound identical; with a strong, deep-frequency "hollow" chatter.
- #2 sounds noticeably higher-pitched; still strong but not nearly as deep.
- #4 sounds comparatively shallow and weak; enough so that it's conceivable that I'm hearing the chatter from the adjacent #3.

[Update: I snugged all 4 injector claws. 2&4 were slightly loose @ maybe 15#; snugged them to 40ish ("firmly snug")
Also re-checked/seated the return T @ #4. Strange test-drive: ran like total crap for 1st 10min(air-bleeding) but then actually running better than before, less smoking on accel & bit more power. Then stetho'd again: now all 4 sound kinda' similar.
Still leaking somewhere aft-top, though. Argh]

- Yeah, it has been smoking up grades.
- Also been having temp issues under load/grades/>75mph speeds, but very probably being caused partially/wholly by my major cooling system mods.

Questions:
- If the #4 injector's base washer or O-ring was failing would I necessarily see an active leak at idle? At higher rpms?
- Can I swap injectors (4&1 for easy access) for purposes of confirming whether the #4 injector needs rebuild/replace vs ECM-pulse or fuel supply/return line issues?

Thanks

[Keys: CRD injector leak leaking jeep liberty diesel fuel spill on engine power loss smoke smoking o-ring o ring copper crush washer livid giant pomeranian etc]

rankom · **Posted:** Tue May 04, 2021 8:47 pm

you need to get the proper tool to properly clean injector cup (cutter tool) this will be much more effective than something like sandpaper. you need 100% seal so no compression escaping by copper washer.

Gypsy62 · **Posted:** Tue May 04, 2021 8:57 pm

Thanks. I've been in the guts of this beast many times. Re pulling injectors I decontaminate the zone, lube the base & then coerce them out sans special tools. Fun? No. Doable? Eventually.

I guess I'm just hoping for voices to remind me of the diagnostic sequence. I use to know it, but am getting old.
Thanks.

WWDiesel · **Posted:** Tue May 04, 2021 9:34 pm

The "O" ring only seals out trash from getting into the injector pocket. The copper crush washer under the injector seals the injector to the combustion chamber. If you are leaking combustion, it may be time to resurface the mating surface between the injector and the head using a tool as pictured below.
If you are leaking fuel, it is most likely one of the fuel fittings or the injector body is cracked.

Gypsy62 · **Posted:** Tue May 04, 2021 10:25 pm

Thanks, WW.
I recalled & reviewed a thread I fueled years ago. I couldn't remember the o-ring &copper washer sequence, but all the great voices in that thread helped clarify that & injector-related diagnostics.

My problem is that May 1 I vacated my casa in Baja & have neither the place nor time to wrench. Add potential(likely) order/delivery time for parts (injector?) and I'm hosed re road-repair.

However, I am reasonably liquid so... if there's any CRD-familiar wrenches in SD or LA (maybe Vegas) I'd be glad to lodge my beast with you for reparation while I handle biz elsewhere. This would be a "No-Rush" scenario, lol.

Any takers PM me & we'll go from there.
Thanks!

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

I would think if you were leaking combustion (forcing fuel out past the copper washer) you'd be able to detect that... like a tissue over the injector, etc.

Seems more likely leaking liquid fuel from somewhere else.

Something like this could be of help:

https://www.amazon.com/Tracer-Products- ... B000JFHNTM

Gypsy62 · **Posted:** Thu May 06, 2021 2:55 am

Developments: good, and very, very bad.
- Test-drove up nearby steep climb but no temp increase(!). Since the Garrett installation, that hill has spiked the gauge to 3/4; this time, steady center like the ol stock behavior. This seems to imply that snugging the two injector base-bolts increased compression & power significantly enough to avoid excessive heat-build.

Although the power-loss/heat issue seemed resolved, it still was leaking fuel near #4. Having copper washers, orings & new return-lines on-hand I decided to get greasy:
- The Crankcase-vent (towards back of head) was missing its' 3rd (aft) bolt as well as the big oring that seals its' back tube.
- Took the #4 injector to a local diesel shop; they tested, inspected and cleaned #4, confirmed that it was okay. Tech suggested swapping #1 & #4 for substitution diagnostics. Done.
- Installed the new return fittings

Wrapped all of the related crap. Started and drove it

- At idle, it ran normal-ish, if a bit loud.
- Test-drove up same grade. Sounded okay, decent power and no smoking.

Then I punched it. Very bad idea. Some loud unfamiliar thunks and then stalled.
Rolled downhill and back into driveway.
Started it back up and there's lots of smoke billowing past the #4 injector.

Before swapping-in the #1 injector, I toiled for over an hour de-contaminating/cleaning the removed #4 injector's well and zone. My fear is that some murderous crap may have slipped into the cylinder during the process. Anybody who has R&R'd a #4 can relate to my trepidation; inaccessibility requires mirrors & cell-cams to observe & confirm progress.

Pulling #4 again in remote hope of identifying/rectifying this NEW problem. Grrr, Argh, Sigh...
There's is nothing as satisfying as fixing a problem by making it WORSE. If anybody has an idea what I screwed-up, please pound on me.

*just viewed thread that also adds "partial/complete crank vent blockage" into mix. Maybe Provent needs cleaning?
Great diagnostic: remove oil filler cap but throw rag over it to catch oil: if smoke comes out of filler hole then injectors aren't the problem.

geordi · **Posted:** Thu May 06, 2021 6:14 pm

Not sure how you have smoke coming from the injector..... But that says that you somehow didn't get the injector seated OR there's another issue happening.

Start with this: You shouldn't need to cut the aluminum on the head to make a seal. Use a shotgun bore mop (fat 12 gauge) SOAKED in brake cleaner. You will need the extension tubes from probably a pistol kit to have the length to put it all the way down the injector bore. But use that, rotating and capturing all the anything in there.

Make sure you got the old crush washer out, that's the only thing I can think of that would create a continuous leak.

Put the injector in and position it / torque the clamp PART WAY before ever connecting the hardline to the rail. THEN do the rail, position and tighten finger tight before finishing clamping torque. Then tighten the rail.

You can use aluminum anti-seize on the injector if you want, and you can SKIP the o-ring if you want or think you will be pulling it apart again soon. It's not critical. a paper towel coiled around the injector and down the tube a bit can show if the fuel is coming from the top or the bottom (if you don't let it get saturated before looking!)

If the injector tested good, then that's not your issue..... So you might be in a place where it needs to come apart to test the head. You might have a cracked head.

Gypsy62 · **Posted:** Thu May 06, 2021 10:03 pm

Thanks, Geordi.
:BINGO:

SOLVED: #4 was loose, and to a lesser extent 1-3. Really weird because when I swapped 1&4 injectors I snugged everything very firm. The fact that they shook-loose after 10min idle then one minute of load then brief WOT baffles me.

One method to determine if there's injector blow-by: with the engine running, you can use a flashlight and inspect for bubbles in the skinny space between the injector and its tube.

A few takeaways:
- Keep a set of (new ) injector copper crush-washers, O-rings, and return-line clips and fittings with the vehicle. These are cheap parts that regularly fail; having them on-hand can save you a LOT of money if road-repairs are required. I just used my extra set to freshen all four injector seats, etc. Time to buy a new set of backups. And they are small for stowing in-vehicle.
- I saw threads specifying that the fsm injector-shoe torque spec is 27# with some recommending 18#. Really? From what I just experienced I can't see how that could be adequately reliable. I cleaned all 4 bolts, coated them with blue (medium) thread-locker and then snugged them between 40-50#. I appreciate the aluminum-risk but these are looong bolts with at least 30 engaged threads; I don't think 50# is too risky, and I don't want to have to check/snug these every visit to my parole offi, I mean, to the pizza parlor.
- Yeah, gun cleaning tools are def the ticket for purifying the injector ports. I also agree that shaving metal with the head on-vehicle seems very ill-advised. Before proceeding with any 'de-mucking' I also suggest sweeping the entire area with magnets to remove any stray metal shards . No gun stuff on-hand, I cleaned the tube with a lint-free around a skinny socket extension.
- Very pleasantly shocked that this power blow-by also appears to have been the central culprit in my elevated under-load temps! I haven't climbed any major mountain passes yet but given the marked improvement in local hill-climbs I'm actually feeling optimistic. Given Southwest summer ambients, swapping heater-on engine-temp reduction for AC was imperative.

Related question: why does the injector sequence matter? Maybe my memory is wrong, but I recall a thread warning against swapping them around. Anyway, in this case swapping 1-4 didn't seem to matter.

As ever, thanks for the knowledgeable counsel!

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

There are minute differences from injector to injector, and those are effectively programmed to the ECM. Swapping the injector without reprogramming means the compensation in effect is wrong. Probably, generally, it doesn't matter much but if you had two injectors with opposite variances and swapped them cylinder to cylinder performance would be affected. You can Google EDC16 injector coding if you wanna dig In.

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

thesameguy wrote:

There are minute differences from injector to injector, and those are effectively programmed to the ECM. Swapping the injector without reprogramming means the compensation in effect is wrong. Probably, generally, it doesn't matter much but if you had two injectors with opposite variances and swapped them cylinder to cylinder performance would be affected. You can Google EDC16 injector coding if you wanna dig In.

You can also reprogramed the ECM for the new sequence. It's a 2 min job !

Gypsy62 · **Posted:** Sat May 08, 2021 8:03 am

Great info! Thanks.
I still have some black smoke above 3/4 throttle; wonder if that could be injector-swap/ECM related. My Garrett & snorkel installs likely messed with the air-fuel calibration as well.

I have the OBD tuning setup, thus far only done one flash (stock flash saved). Very satisfying, and I've been waiting to confirm the stability of all my major mods before engaging one of our flash gurus.

I'm school'd that swaps require dialing, but any time you replace an injector you should re-calibrate the ecm as well, no? Is the topic of re-tuning the injector array buried somewhere in the mighty "DIY ECU FLASH" thread, or separately?
If not already a solo thread, may be a good idea to start one.

I haven't climbed the beast lately, but there is so much ground covered in that flash thread that it seems a decent idea to create "Tuning" sub-categories with a searchable index. Granted, it is asking a lot of someone in authority to invest that time.
Aloha

Tree Catcher · **Posted:** Tue May 18, 2021 10:32 pm

Do we have the same jeep? Mine is now doing the same.

krb · **Posted:** Wed May 19, 2021 5:53 am

geordi wrote:

...Start with this: You shouldn't need to cut the aluminum on the head to make a seal. Use a shotgun bore mop (fat 12 gauge) SOAKED in brake cleaner. You will need the extension tubes from probably a pistol kit to have the length to put it all the way down the injector bore. But use that, rotating and capturing all the anything in there. ...

Now I like that idea! I've got to replace my #4 crush washer and will now be using my gun cleaning kit! Thanks Geordie.

SJBrooks · **Joined:** Tue Mar 11, 2014 11:01 am **Posts:** 80

Ran across this older thread and want some further input on it. Has anybody experienced any problems when torquing the injector clamp hold-down bolts to 40-plus ft/lbs? What’s the max that anybody’s torqued them down to successfully?

Thanks in advance for the feedback!

Steve

WWDiesel · **Posted:** Sat Apr 26, 2025 10:18 pm

SJBrooks wrote:

Ran across this older thread and want some further input on it. Has anybody experienced any problems when torquing the injector clamp hold-down bolts to 40-plus ft/lbs? What’s the max that anybody’s torqued them down to successfully?
Thanks in advance for the feedback!
Steve

Not sure where you got 40+ ft. lbs.
FSM in section 14 page 85 says:
(2) Install fuel injector retainer and bolt (Fig. 16).
Torque bolt to 32.4 N·m.

Fuel Injection Pump Retaining Nuts 32.4 N·m = 23.8 Ft. Lbs.

SJBrooks · **Joined:** Tue Mar 11, 2014 11:01 am **Posts:** 80

Hey WW,

Got the 40+ from a reply, above. I’m aware of what the FSM says, but just poking around to see if anybody’s successfully gone above that. I’ve got a small amount of pressure leakage past my #3 injector and want to see if some further tightening will fix it before pulling it back out and cleaning up the seat with a tool.

Steve

WWDiesel · **Posted:** Sun Apr 27, 2025 3:54 pm

Pull it out, ream/cut the seat with an injector seat reamer tool, install new crush washer, torque to proper specs.
Plenty of the tool kits available online, Amazon and others. Not very expensive!

Don't risk pulling the threads out of the aluminum head by over tightening the hold-down bolt. Bad idea! :banghead:

SJBrooks · **Joined:** Tue Mar 11, 2014 11:01 am **Posts:** 80

Yea, WW, I wasn’t comfortable going above the established torque in the first place; cutting the seat is definitely the best way to go. Do you know the diameter of the injector bores? I want to make sure I get a kit with the proper cutter.

Thanks as always,

Steve

layback40 · **Posted:** Sun Apr 27, 2025 8:21 pm

SJBrooks wrote:

Yea, WW, I wasn’t comfortable going above the established torque in the first place; cutting the seat is definitely the best way to go. Do you know the diameter of the injector bores? I want to make sure I get a kit with the proper cutter.

Thanks as always,

Steve

When using new (or old) copper washers, it's always best to anneal them before use. A propane torch will get them hot enough & let them slowly cool down. When you pull the old washer, you may be able to see the mark (track) from the leak on it.

Diagnosing #4 leak and/or injector failure.

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