Help Diagnose Injector Failure
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Excursion's 4ever!
Joined: Jun 2010
Posts: 346
Likes: 0
From: Yucca Valley, CA
Help Diagnose Injector Failure
I could use the SME's on this forum to help me understand what and why I have experienced injector failure. This on a motor that was recently rebuilt, has just under 25k miles on it, and the injectors were new, not reman.
On December 22nd while bringing my son home for Christmas when my Excursion began to knock, smoke, and then it got louder and allot more smoke. I pulled over and shut it down. The motor was hydro locked. Removed all the injectors and removed allot of fuel from cylinders 1 & 3. Here are photos of the injectors from that side of the motor and you can see the injectors that are smoked dark from the fuel/smoke entering the injector cup.
Can you please share your thoughts on how this could occur? I understand that the root cause may be cracked injector tips, and/or improper torque on the injectors themselves in the head.
All eight injectors are back at the manufacturer now being gone through. Your help will allow me to ensure the re-installation is done correctly and the cause is determined. Thanks.
On December 22nd while bringing my son home for Christmas when my Excursion began to knock, smoke, and then it got louder and allot more smoke. I pulled over and shut it down. The motor was hydro locked. Removed all the injectors and removed allot of fuel from cylinders 1 & 3. Here are photos of the injectors from that side of the motor and you can see the injectors that are smoked dark from the fuel/smoke entering the injector cup.
Can you please share your thoughts on how this could occur? I understand that the root cause may be cracked injector tips, and/or improper torque on the injectors themselves in the head.
All eight injectors are back at the manufacturer now being gone through. Your help will allow me to ensure the re-installation is done correctly and the cause is determined. Thanks.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Classic loose injector. The O-rings on #1 did a great job of holding the combustion gasses back (not too loose yet), but #3 was just far too loose and let fly.
Step one: Drain your coolant and pressure-test your cooling system. While the pressure is in there, spray the injector cups with silicone spray and watch for bubbles. Pay very close attention to #1 and #3, because they were exposed to combustion gasses and pressures.
This problem didn't likely sneak up on you, you would have warning signs before the failure: Smoky cold starts, increased knocking, a partial or full miss, bucking at low acceleration, and stinky exhaust. I'll also offer you you may have been playing phone tag with your tuner.
Hot-torquing the injectors with a proper torque wrench usually prevents this, but understanding the sounds under the hood and watching for an elevated IPR at warm idle can clue you in on loose injectors.
Step one: Drain your coolant and pressure-test your cooling system. While the pressure is in there, spray the injector cups with silicone spray and watch for bubbles. Pay very close attention to #1 and #3, because they were exposed to combustion gasses and pressures.
This problem didn't likely sneak up on you, you would have warning signs before the failure: Smoky cold starts, increased knocking, a partial or full miss, bucking at low acceleration, and stinky exhaust. I'll also offer you you may have been playing phone tag with your tuner.
Hot-torquing the injectors with a proper torque wrench usually prevents this, but understanding the sounds under the hood and watching for an elevated IPR at warm idle can clue you in on loose injectors.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Are the injectors in order? If so, it's 1 & 5 with the problem.
Looks like the injectors weren't seated properly. The crush washer looks like it never really got crushed. Also, what's with the damage on the edge of the crush washer?
Hindsight says you should have laid a straight edge across the top of the injectors to see if they were all fully seated.
Torquing the injector hold down bolts doesn't help if the injectors aren't fully seated yet. If it's a cup issue, you should be able to tell that with little to no pressure on the coolant.
I've seen a cracked cup leak with no pressure at all. Didn't even know the cup was cracked other than the small drop of coolant that would appear and then run down into the cylinder after the injectors were removed.
Looks like the injectors weren't seated properly. The crush washer looks like it never really got crushed. Also, what's with the damage on the edge of the crush washer?
Hindsight says you should have laid a straight edge across the top of the injectors to see if they were all fully seated.
Torquing the injector hold down bolts doesn't help if the injectors aren't fully seated yet. If it's a cup issue, you should be able to tell that with little to no pressure on the coolant.
I've seen a cracked cup leak with no pressure at all. Didn't even know the cup was cracked other than the small drop of coolant that would appear and then run down into the cylinder after the injectors were removed.
Lead Driver
Joined: Sep 2005
Posts: 9,399
Likes: 188
From: Norco,CA
Bad luck for sure. Check those cups for sure. I'd pressure test the whole system to make sure. It could be just a bad injector but I'd want to know just like you. Hope there wasn't two copper washers in that one hole.
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