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Fuel Leak seeping out of Head

14463 Views 22 Replies 5 Participants Last post by  Jimbowe
:S:I have had fuel leaking or ozzing from out of the bottom of the insert-under the nut of the fuel line on#4 cylinder

here is every thing i have done and replaced as of this morning;

1- Replaced the connector tube & o-ring w/new one from cummins

2- New hp. fuel line fromVP to head from cummins

3-removed injector, connector tube, and line;
cleaned & inspected..found nothing wrong o-ring looked good so i blew out the holes and swabbed them out with a rag looked in them to besure they were ok. then i swapped cyl's with #3 meaning i put #4 injector in #3cyl & #3 in #4cyl.

STILL LEAK'S IN THE SAME PLACE:banghead:
:confused013:
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Discussion Starter · #2 ·
could the hold down clamps not being tight enough cause this leak??
I set torque on outside bolts @ 89inch lbs but cannot reach the back ones for the rocker... when i removed the injector the clamps slid out from under the rear bolt real easy.. more than normal...
 

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You might take connector out and inspect (as possible) for a burr or damage in passage in cylinder head. Look at O-ring for damage again. You put a new tube and o-ring but did not stop leak. I suppose is possible the passage could be cracked or scored from some previous encounter. Are you tightening the nut sufficentlly. They will take more than 29 ft#.
 

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Discussion Starter · #4 ·
You might take connector out and inspect (as possible) for a burr or damage in passage in cylinder head. Look at O-ring for damage again. You put a new tube and o-ring but did not stop leak. I suppose is possible the passage could be cracked or scored from some previous encounter. Are you tightening the nut sufficentlly. They will take more than 29 ft#.
Thanks for responding dozer 12216
Uhh.... There should'nt be fuel in between the connector tube and passage should they :confused013:

would an inproper seal in the injector bore in the head cause this??
 

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Yes, there is return fuel. The O-ring at top of injector keeps fuel from leaking into engine oil. The copper washer seals the bottom of injector. (if this washer leaks combustion presuure will leak into return system and possiblly blow up fuel tank.) The O-ring on connector tube seals fuel from running out where you have your leak. There is also a drilled passage connecting all injector holes to the fitting at rear of head. this returns fuel back to the tank, along with excess fuel from injector pump. (information- in order for injectors to self lubricate a small controlled leak lubricates the precision fit components.) This leak is why the return passage exists. So very low pressure fuel is present around connector tube and injector body. This fuel returns to tank through the fuel return system.
 
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Discussion Starter · #6 ·
Yes, there is return fuel. The O-ring at top of injector keeps fuel from leaking into engine oil. The copper washer seals the bottom of injector. (if this washer leaks combustion presuure will leak into return system and possiblly blow up fuel tank.) The O-ring on connector tube seals fuel from running out where you have your leak. There is also a drilled passage connecting all injector holes to the fitting at rear of head. this returns fuel back to the tank, along with excess fuel from injector pump. (information- in order for injectors to self lubricate a small controlled leak lubricates the precision fit components.) This leak is why the return passage exists. So very low pressure fuel is present around connector tube and injector body. This fuel returns to tank through the fuel return system.
Many Thanks dozer, that is good information on the fuel return..
i never knew that was there or why:thumbsup:
What would increase this pressure around the tube to the point that it would push past the connector tube o-ring
and leak out of head??

where is the return passage in the head??
 

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Just a shot in the dark, I saw in your sig that you have aftermarket injectors. Did you get the leak after the injector install. What im thinking, is it possible that #4 injector has 2 copper washers?
 
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Just a shot in the dark, I saw in your sig that you have aftermarket injectors. Did you get the leak after the injector install. What im thinking, is it possible that #4 injector has 2 copper washers?
Good call, sometimes the washer don't come out with the injector and will stay in the head until it is fished out. When an injector is pulled a new 1.5 mm copper washer/shim/gasket should be used when it is put back in, to ensure a good seal.:thumbsup:

Injectors
 
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Discussion Starter · #9 ·
Just a shot in the dark, I saw in your sig that you have aftermarket injectors. Did you get the leak after the injector install. What im thinking, is it possible that #4 injector has 2 copper washers?
I did get the leak a few weeks ago, I installed the DDP injectors in November past year. I will double check this but i am almost sure that the old injectors all had the copper washers when i packed them up to return for core.

Thank you
 

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Just a shot in the dark, I saw in your sig that you have aftermarket injectors. Did you get the leak after the injector install. What im thinking, is it possible that #4 injector has 2 copper washers?
good thought but OP says he swapped injectors and the leak stays at hole #4... perhaps the copper washer is stuck in the injector bore?
 

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Discussion Starter · #11 ·
Good call, sometimes the washer don't come out with the injector and will stay in the head until it is fished out. When an injector is pulled a new 1.5 mm copper washer/shim/gasket should be used when it is put back in, to ensure a good seal.:thumbsup:

Injectors
new copper washers were installed with the injectors in November, have only clocked about 3,000 miles since then. i agree it would be a good preventive measure, but dont have local cummins store close to me or i would replace
but the washer looks fine,
 

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Maybe your injectors are bad, put them in a box and send them to me! I will examine them! :hehe::hehe::hehe::hehe::hehe: But seriously , keep us informed on your findings.
 

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Discussion Starter · #13 ·
O.K. i think i found the problem, the injector is bad. :banghead: I know it go aginst al logic but injector has to be the problem.
Last nite when i pulled out both #3 & #4 and swapped them i kept the injector tubes paired with the injector they were with, I must have nicked the o-ring on the old one i put back into #4 and they both must have been leaking and i just did'nt see the leak on #3 by it being dark with little light.

Today i pulled the connector tubes back out and replaced o-ring on both and when i started engine and let it run for a short while # 3 was pooring fuel and #4 was dry... ran for a long time CT at 190 degrees still # 3bleeding fuel and #4 dry

Has to be the injector

Thanks guys for all the responce:thumbsup:
 

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the leak is at connector tube O-ring. Not the injector. Think some more and lube new o-rings when you put them in. The copper washers are one use items. Copper hardens when compressed and does not seal reliably on recompressing. remember copper leak equals compression in return system. Injector body leak will pressure entire return system, not just one place. Upper injector O-ring puts fuel in oil. The tip of connector tube that seals to injector line could be damaged also.
 

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Discussion Starter · #16 · (Edited)
the leak is at connector tube O-ring. Not the injector. Think some more and lube new o-rings when you put them in. The copper washers are one use items. Copper hardens when compressed and does not seal reliably on recompressing. remember copper leak equals compression in return system. Injector body leak will pressure entire return system, not just one place. Upper injector O-ring puts fuel in oil. The tip of connector tube that seals to injector line could be damaged also.
That connector tube is new, I looked at it again yesterday when i had it out and replaced o-ring again both ends were perfect, yes i always lube the o-ring on tube and injector.

I cleaned out both connector tube passages in the head and looked back in them.. felt of the o-ring seat with my finger everything looked & felt normal. i looked at the injector where the tube seats and i see compression marks, dark ring....no burs or nick... its possiable that is where the leak is comming from:confused013:

but the fact is that the leak has moved from #4cyl to #3cyl after i swapped them around still makes me thank its the injector or something pertaining to the injector.....HOLD ON:shock:

HEY:doh: I just thought of something when reading back over your quote, when i moved #4 injector to #3cyl the same copper washer was kept with that injector,
from what you said in the above thread, if the copper washer leaked compression it would pressurize the return & connector tube passage & most likely past the connector tube o-ring

But that would mean that the copper washer was the original source of the leak and it had never been removed or re-used, was put in with new injectors 2-months ago.
:confused013:
What do you think dozer... is it possiable??



 

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Discussion Starter · #17 ·
Think I Will Still Pop Test Them When I Take The Back Out
 

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Discussion Starter · #18 · (Edited)
I know that the torque spec for the hp injector line nuts are 28ft.lb but how would you torque them??

I have been using a stanard 19mm wrench...yesterday after i seen it was still leaking and i thought it may be possiable i have not been getting it tight enough so itighten it a little more. still leaked.. then i tighten the p$$ out of it, but i dont think that you could put much more than 30ft./lbs with a short wrench in that confined area??
 

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I know that the torque spec for the hp injector line nuts are 28ft.lb but how would you torque them??

I have been using a stanard 19mm wrench...yesterday after i seen it was still leaking and i thought it may be possiable i have not been getting it tight enough so itighten it a little more. still leaked.. then i tighten the p$$ out of it, but i dont think that you could put much more than 30ft./lbs with a short wrench in that confined area??
Tighten them with a 19mm flarenut crowsfoot, short extension, and a torque wrench. :doh:

When you "tighten the p$$ out of it" you have no idea how much torque you have applied. The fittings can be damaged by applying too much torque, then you will need to replace the high pressure lines. $$$$$ :shock:
 

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Discussion Starter · #20 ·
Tighten them with a 19mm flarenut crowsfoot, short extension, and a torque wrench. :doh:

When you "tighten the p$$ out of it" you have no idea how much torque you have applied. The fittings can be damaged by applying too much torque, then you will need to replace the high pressure lines. $$$$$ :shock:
HEY" THATS A GOOD IDEA:.. HOW ARE YOU GOING TO GET ON THE BACK 2 LINES :doh:

I seriously doubt that i could have put enough torque to damage the fittings..specially laying over the front of truck on my stomach with a short wrench
 
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