Injector Cap Leak/Damaged Injector 6.9 IDI

[PossumF250]

Hello all, this is my first post here, but I'm a longtime reader and this forum has helped me solve a number of problems with my truck. My current problem, which I have not yet seen a solution for here or elsewhere, is an injector cap that will not stop leaking. I have tried three caps and probably six sets of Viton o-rings (installed with lithium grease) on this one injector. Each time the cap snaps/clicks into place, but starts leaking badly within a couple minutes of starting. I have recently replaced caps and o-rings on several other injectors, none of which leak now, except this one. The leaky injector has a few fairly deep scratches in and around the grooves where the o-rings go (likely from when I removed the old o-rings), so I'm guessing fuel is getting past the o-rings in those scratches. My question is: is there anything I can do to get the o-rings to seal? I thought about putting RTV silicone in the grooves before reinstalling the o-rings in order to fill the scratches, but I've read it can flake and contaminate the fuel. I figured that surely someone else has run into this problem, and I'd rather not replace the injectors if there's another solution.

 

[Dane Rickford]

It’s possible that you’re leak is coming from the clamp seal where the injector line meets the injector. If the 5/8 cap on the injector line gets torqued down too hard, it can damage the clamp seal and compromise the seal of the line to the injector because the extra torque deforms the cone part of the clamp seal. I had this happen a couple times on two different injection lines, and the only way to fix it is to get a new line. I don’t know if this is your issue, but that’s just my two cents

 

[riphip]

& do you have any line clamps missing on that side? Should have 2 on left & 2 on Right fuel hard lines

 

[Scotty4]

As far as O-rings are concerned, it is always nice to have a brass (or plastics depending on application) pick set for removal to prevent gouging. And O-ring and its groove are designed to match perfectly so the material squish fills the groove. Any nick or gouge will decrease its sealing efficiency. Any raised edge can also damage the O-ring. You could lightly file any raised edge but a big groove is tough to seal in a fuel system as you can’t use fillers as you stated with the RTV. Maybe people have had success and there is an old timer trick I don’t know yet, but I’m not too sure. I will be watching here to learn.

 

[Shadetreemechanic]

I would remove the injector before trying to file or sand it. You don't want those filings to get in your injection system.
I just pulled my entire injector collection off the shelf and sorted and tested them for a truck I am working on this past weekend. Depending on where you are in TN you could come get one if needed.

 

[chillman88]

Well if you're in a pinch, you could try to goop some Hylomar over the gouge, put the o-ring on a goop them up good with the Hylomar too. It's fuel resistant so there's a half a chance of it holding up, plus it's a great thing to have in the toolbox. I use it all the time on thermostat gaskets and the like.

https://www.amazon.com/dp/B00J4Z7N9I/ref=cm_sw_r_cp_awdb_t1_VMbQEbQBYXWYS

 

[PossumF250]

Thanks for all the responses!

It’s possible that you’re leak is coming from the clamp seal where the injector line meets the injector. If the 5/8 cap on the injector line gets torqued down too hard, it can damage the clamp seal and compromise the seal of the line to the injector because the extra torque deforms the cone part of the clamp seal. I had this happen a couple times on two different injection lines, and the only way to fix it is to get a new line. I don’t know if this is your issue, but that’s just my two cents

It's certainly possible I overtightened that cap and damaged the clamp seal. Is there any way I could tell if this is the problem before replacing that injector line? I can't tell if fuel is leaking up out of the plastic return cap or down from the 5/8 cap on the line (as I'm assuming would happen if the clamp seal were damaged). I don't know if this suggests one problem or the other, but air also seems to be getting into the fuel system because it takes more cranking than normal to start.

& do you have any line clamps missing on that side? Should have 2 on left & 2 on Right fuel hard lines

Both line clamps are in place on that side (and the other).

Well if you're in a pinch, you could try to goop some Hylomar over the gouge, put the o-ring on a goop them up good with the Hylomar too. It's fuel resistant so there's a half a chance of it holding up, plus it's a great thing to have in the toolbox. I use it all the time on thermostat gaskets and the like.

https://www.amazon.com/dp/B00J4Z7N9I/ref=cm_sw_r_cp_awdb_t1_VMbQEbQBYXWYS

So it looks like if the problem is the injector itself and not the clamp seal, my two options (besides replacement) are Hylomar in the o-ring grooves or removing the injector and sanding/filing its scratches or gouges. Between these two, is there one I should try before the other? Also, are there any potential negative affects of using Hylomar in this application, and is that sort of a temporary fix? I don't rely on it for daily transportation, so I'm not really in a pinch to get it back on the road ASAP. All that to say, thinking longterm, I don't mind replacing the injectors if that's what I have to do, but I'm happy to give Hylomar (or sanding/filing) a try first if that's a good, viable option.

 

[Dane Rickford]

Is there any way I could tell if this is the problem before replacing that injector line?

One way of telling if the injector line has been over torqued is by simply examining the cone tip of it. Here is an example:

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It is kinda hard to see, but the line on the left is damaged to the point it leaks pretty bad, while the line on the right is in decent shape and probably wouldn’t leak at all. A damaged line will look “rolled” halfway down the cone tip, while a line that is in good condition will be smooth, or very nearly smooth, from the top of the tip cone to the bottom of the cone. I hope this is helpful, I’m not the best at describing things

 

[PossumF250]

A damaged line will look “rolled” halfway down the cone tip, while a line that is in good condition will be smooth, or very nearly smooth, from the top of the tip cone to the bottom of the cone. I hope this is helpful, I’m not the best at describing things

Thanks! That definitely helps. I can see the difference in the picture. I'll take a look at the line on my truck and see if there's any damage like that visible.

 

[chillman88]

How old are your injectors?

 

[Thewespaul]

Typically the injectors will mushroom before the lines since the lines are harder, if it’s leaking from above the nut then it’s the line, if it’s not leaking above the nut then the plastic cap is leaking and you need to repair the gouges or replace the injectors.

 

[PossumF250]

How old are your injectors?

Unfortunately, I have no idea. I don't know when or if they've been replaced. They may be original to the engine, but the engine was replaced at some point so I have no idea how many miles it has either.

Typically the injectors will mushroom before the lines since the lines are harder, if it’s leaking from above the nut then it’s the line, if it’s not leaking above the nut then the plastic cap is leaking and you need to repair the gouges or replace the injectors.

Since I can't tell if it's leaking from the nut or the cap, is there any way I could tell by looking if the injector is mushroomed? I just removed the injector line today to get a good look at it, and I don't see any signs of damage on the tip of the line itself.

 

[Thewespaul]

Unfortunately, I have no idea. I don't know when or if they've been replaced. They may be original to the engine, but the engine was replaced at some point so I have no idea how many miles it has either.



Since I can't tell if it's leaking from the nut or the cap, is there any way I could tell by looking if the injector is mushroomed? I just removed the injector line today to get a good look at it, and I don't see any signs of damage on the tip of the line itself.

Can you take a picture of the top of the injector?

 

[chillman88]

Unfortunately, I have no idea. I don't know when or if they've been replaced. They may be original to the engine, but the engine was replaced at some point so I have no idea how many miles it has either.

My only thought was might not hurt to just change them depending on how old they are. If you're able to.

I'm sure if it can be sorted out, Wes will be able to help.

 

[PossumF250]

Can you take a picture of the top of the injector?

Here it is:

You must be registered for see images attach

Also, I would have posted a picture of the injector line earlier, but I hadn't figured out how. So here that is:

You must be registered for see images attach

My only thought was might not hurt to just change them depending on how old they are. If you're able to.

I have to say, the idea of having a new set of injectors is appealing since I don't know how old they are, and I'm in the process of replacing other things anyway. If that injector is mushroomed, I'll replace them. If not, I'm thinking I'll try to smooth out the scratches and gouges, but if it still leaks after that, I'll replace them.