Fuel Leak at #5 cylinder

[Greenlee]

I searched the past 45 pages of articles looking before asking. 1999 Dodge Cummins 2500 with fuel leak at #5 cylinder at injection connector tube and injection line nut. The tube had a cracked O-ring so it was replaced with a new tube. On start up no leak, 1 mile down the road no leak, up on the interstate for 6 miles and it's leaking again. Retightened but still leaking. Pulled the line off to check the mating surfaces with also looked good. Still leaking, any ideas?

Part 2: This is for me to understand. The tubes pops out easy, no problem getting the removal tool on the tubes. Once in place how does it stay in place and not turn when tightening? First time I changed my VP44 I had to double wrench the 3/4" or 19mm nuts to break them. Way past the recommended 26 or so ft/lbs. Does the slight taper fitting in the injector help keep the tube from turning? Just curious. Thank you for your time.

[dripley]

I have a couple thoughts on this. One, the new connector tube might be slightly different from the old and not sealing to the injector. That is letting fuel by the seal and the pressure is pushing by the o ring. The only cure I know for that would be to loosen the line and then the injector hold down. Then snug up the fuel line to the head and it should cure that problem. Two, if the old connector tube only had a bad o ring on it, replace the o ring and reinstall the old tube. The old tube might seal to the injector. I think I would try 2 first and see if that works.

 

 When you tighten the fuel line nut to the head it never contacts the connector tube to make it turn. It puts pressure on the fuel line to the connector tube to seal them. It also transfers pressure to the connector tube and the injector to seal that connection.  

 

 My money is on the connector tube to injector seal since the other joint looked good to you before install.

Edited August 25, 2017 by dripley

[Mopar1973Man]

1 hour ago, dripley said:

 My money is on the connector tube to injector seal since the other joint looked good to you before install.

 

This is the only thing I will disagree with. The injector to connector tube seal would only leak into the return rail. The leakage on the manifold would only be the high pressure line to connector tube or the o-ring. Now if there is a puddle of fuel on the cap area of the nut it will expand out and weep on the manifold. Typically in about a week time it will dry up and be fine. You can check with a can of brake clean on a warm engine then drive again if it continues to get wet then its connector tube or o-ring issues. 

[Dieselfuture]

Sometimes it takes few days for fuel to stop coming out from behind the nut. In my opinion it's extra fuel behind the nut that comes out when engine is hot, aventualy it stops leaking, no need to kill that nut if it's already over tighten. If still leaking after few days then mating surfaces not true. If you have no hard starts let it go for few days and see what happens. 

And yes some of my lines are over tighten, but that's just how it is sometimes. 

Edited August 26, 2017 by Dieselfuture

[Greenlee]

1 hour ago, dripley said:

I have a couple thoughts on this. One, the new connector tube might be slightly different from the old and not sealing to the injector. That is letting fuel by the seal and the pressure is pushing by the o ring. The only cure I know for that would be to loosen the line and then the injector hold down. Then snug up the fuel line to the head and it should cure that problem. Two, if the old connector tube only had a bad o ring on it, replace the o ring and reinstall the old tube. The old tube might seal to the injector. I think I would try 2 first and see if that works.

 

 When you tighten the fuel line nut to the head it never contacts the connector tube to make it turn. It puts pressure on the fuel line to the connector tube to seal them. It also transfers pressure to the connector tube and the injector to seal that connection.  

 

 My money is on the connector tube to injector seal since the other joint looked good to you before install.

I told my brother the same exact thing, almost word for word this afternoon. He has my 99 now and is learning how to deal with diesels. I will know in the morning if he followed this advice. I'm going to copy and send to him so he can see I'm not the only one that has come up with the same conclusion. I appreciate your advice, makes me feel pretty good.

 

1 hour ago, dripley said:

I have a couple thoughts on this. One, the new connector tube might be slightly different from the old and not sealing to the injector. That is letting fuel by the seal and the pressure is pushing by the o ring. The only cure I know for that would be to loosen the line and then the injector hold down. Then snug up the fuel line to the head and it should cure that problem. Two, if the old connector tube only had a bad o ring on it, replace the o ring and reinstall the old tube. The old tube might seal to the injector. I think I would try 2 first and see if that works.

 

 When you tighten the fuel line nut to the head it never contacts the connector tube to make it turn. It puts pressure on the fuel line to the connector tube to seal them. It also transfers pressure to the connector tube and the injector to seal that connection.  

 

 My money is on the connector tube to injector seal since the other joint looked good to you before install.

I'm a little lost on this since it's been a while since I have worked on the 24v. Help me remember please, the threaded end of the tube threads directly into the female nut on the injector line, is this right or wrong. I have spent an hour or two looking at tubes to see if I could spot any noticeable difference. So in my thinking or what I remember is the tube seats into the injector at a tapered point on the injector, at the same time the O-ring seats and the threads at the other end are showing so you can thread the 3/4" or 19mm nut to the tube??????????? Is there something I am not remembering?

27 minutes ago, Mopar1973Man said:

 

This is the only thing I will disagree with. The injector to connector tube seal would only leak into the return rail. The leakage on the manifold would only be the high pressure line to connector tube or the o-ring. Now if there is a puddle of fuel on the cap area of the nut it will expand out and weep on the manifold. Typically in about a week time it will dry up and be fine. You can check with a can of brake clean on a warm engine then drive again if it continues to get wet then its connector tube or o-ring issues. 

Thank you MoparMan, I'll pass this on as well. Just as "driply" mentioned about removing the valve cover and take the hold down tab  at the injector loose then push the tube in and retighten. The leak which is not high pressure but began to leak worse after the new tube was put in. I'll get more info in the morning. Hope MoparMom is doing good. Thank you

34 minutes ago, Mopar1973Man said:

 

This is the only thing I will disagree with. The injector to connector tube seal would only leak into the return rail. The leakage on the manifold would only be the high pressure line to connector tube or the o-ring. Now if there is a puddle of fuel on the cap area of the nut it will expand out and weep on the manifold. Typically in about a week time it will dry up and be fine. You can check with a can of brake clean on a warm engine then drive again if it continues to get wet then its connector tube or o-ring issues. 

I need to read things better, I agreed with "driply" on the injector seal also that I it might have to have the hold down tab untightened. But you are saying if it was leaking at the injector and tube where they connect and the O-ring is not leaking then it would simply be part of the excessive fuel returning to the tank and not showing at the high pressure line nut. If it was leaking at the injector would you notice a big difference in mileage or performance?

17 minutes ago, Dieselfuture said:

Sometimes it takes few days for fuel to stop coming out from behind the nut. In my opinion it's extra fuel behind the nut that comes out when engine is hot, aventualy it stops leaking, no need to kill that nut if it's already over tighten. If still leaking after few days then mating surfaces not true. If you have no hard starts let it go for few days and see what happens. 

And yes some of my lines are over tighten, but that's just how it is sometimes. 

Good advice, and I agree on the tightening, I torqued the nuts before but a couple needed a little more, so I just tightened them all the same with a little extra, it happens just like you said. Thanks

[dripley]

1 hour ago, Greenlee said:

 

 

3 hours ago, dripley said:

 

I'm a little lost on this since it's been a while since I have worked on the 24v. Help me remember please, the threaded end of the tube threads directly into the female nut on the injector line, is this right or wrong. I have spent an hour or two looking at tubes to see if I could spot any noticeable difference. So in my thinking or what I remember is the tube seats into the injector at a tapered point on the injector, at the same time the O-ring seats and the threads at the other end are showing so you can thread the 3/4" or 19mm nut to the tube??????????? Is there something I am not remembering

 

The threads on the injector tube are only there for removal. The nut on the fuel lines actually threads onto the head and holds everything together. I just use a flat head screw driver to pop mine out. If it screwed on to the tube and not something to anchor everything the engine would spit every thing out when you started.  The steel in the connector tubes is super hard. I have chucked mine in a drill to spin them for cleaning with scotch brite pad. The chuck has never left a mark on them. It is like tool steel on steroids.

 

My money is still on the same horse.

[Greenlee]

13 hours ago, dripley said:

The threads on the injector tube are only there for removal. The nut on the fuel lines actually threads onto the head and holds everything together. I just use a flat head screw driver to pop mine out. If it screwed on to the tube and not something to anchor everything the engine would spit every thing out when you started.  The steel in the connector tubes is super hard. I have chucked mine in a drill to spin them for cleaning with scotch brite pad. The chuck has never left a mark on them. It is like tool steel on steroids.

 

My money is still on the same horse.

I guess I'm going to have to see it up close again. Thanks for explaining it to me and thanks for taking the time to address this post.

[Shainer]

Think of it as compression fittings.  As you tighten the injector line down it  forces the injector line into the connector tube which is then forced onto the injector.  If you are leaking externally and you have it cinched down pretty tight then you probably nicked the o-ring on the connector tube.  #5 and #6 are not the most fun to play with so chances are a bit higher to damage the o-rings for those cylinders.  With new o-rings those tubes should take quite a bit of resistance to get the connector tube to fully seat.

 

Order a bag to keep in stock.

https://www.amazon.com/gp/product/B005RUQRYQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

[Greenlee]

Well, here's the latest. The new tube was taken out again, the inside of the entrance hole for #5 tube was cleaned again the dried then another cleaning. The tube was oiled from end to end and placed back in and seated then turned CW and CC. My brother repeated this several times. When we discussed it on the phone he mentioned the injector line at some tension on it that made it pull down. You could not turn it by hand more than a couple of threads. I told him to gently move the line for better alignment which he planned on doing anyway. With that done you could screw the cap nut (3/4"/19mm) all the way down by finger. After tightening and cleaning excessive oil from around the line he took it out for a test drive. No leaks. It starts up instantly. So the banjo joint at the rear of the head is new along with the Parker Tee and new grommets. No leaks anywhere. Thank you for all the advice, it was extremely helpful.

22 minutes ago, Shainer said:

Think of it as compression fittings.  As you tighten the injector line down it  forces the injector line into the connector tube which is then forced onto the injector.  If you are leaking externally and you have it cinched down pretty tight then you probably nicked the o-ring on the connector tube.  #5 and #6 are not the most fun to play with so chances are a bit higher to damage the o-rings for those cylinders.  With new o-rings those tubes should take quite a bit of resistance to get the connector tube to fully seat.

 

Order a bag to keep in stock.

https://www.amazon.com/gp/product/B005RUQRYQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

That's a great way of looking at this Shainer I understand now what's going on. Could not remember how it all looked. Thank you. 

By the way, appreciate the link too.

Hey Shainer, great looking Chauffeur you have there.

Edited August 26, 2017 by Greenlee
forgot to add something

[dripley]

1 hour ago, Greenlee said:

I guess I'm going to have to see it up close again. Thanks for explaining it to me and thanks for taking the time to address this post.

Your welcome. Happy to hear of the good ending.

[Mopar1973Man]

Darn misalignment issues. Funny how the wrong order of installing parts will create such strange issues.

[lrhull]

I just found tonight I have a leak on #3. It's on the outside of the manifold. I've had this before on I think 2 and 4 and I had a local diesel shop fix it they changed the o ring. This time I thought I might take a stab at it. So if I understand correctly I can use a 3/4 wrench on the nut, loosen the high pressure line and pull it apart, and the o ring should be right there, change it and put it back together? Sounds simple.

[dripley]

The o ring is on the connector tube. You loosen the nut and then have to move the high pressure line over enough to pull out the tube. You will probably have to loosen a clamp or two to get some play in the line to do that. Then you can use a screw driver to pop out the tube.

 You might have to remove the intake horn for #2. I think it is in the way. None of this is hard to do just pricey when you pay someone 75 bucks an hour to do it.