Intermittent Injector Leak

[AnotherOldJeepGuy]

One of the 6 is leaking, but it is not constantly leaking.  I did manage to catch a time of "leaking a lot" on video, but I don't know how to get a video from my phone posted here.  I am about to start disassembly debug.  I do have a new injector I can install, but I can't tell for sure the injector is really the problem.  I generally can't catch the active leak, I can just smell it and notice damp parts. 

 

When I could witness gas leaking, it was puddling below the point where the injector is installed into the engine, and I still could not see exactly where it was coming from.  But if you compare the leaking injector to one that is not, it appears the injector is damp from top to bottom, suggesting the leak might be at the highest point, or, it was being squirted upwards and I just don't get to see that (and I don't see evidence on the inside of the hood to suggest anything has been squirting upward).

 

 

During the time I caught this actively leaking, there was smoke coming out in a few places out from under the heat shield, I presume it was the leaking fuel being heated on the intake and evaporated.  When I can't see the active leak, I don't see the smoke either.

 

Note that I replaced the rings on all of the injectors about 6-9 months ago because of smelling gas and at lease one damp injector then (I think the same one but not sure).  Since I had it out I replaced all the o-rings.  I did not like the new o-rings because they seemed fatter, and because of that were very difficult to insert into the rail.  The ID seemed to be sufficiently similar.  What I didn't like was that the original (broken) had a flattened outer edge, the new one was round.  I didn't have much luck finding any new ones that were flattened, and decided to assume the original may be flattened by being under pressure and heat for 30 years.

 

 

So, most of the above is posted for comments at the moment, since as far as I can say right now, the only actual question I have is, do I need to get my hands on "pre-edge-flattened" rings, and if so any suggestion on where and/or part number, or are the new donut shaped ones OK (albeit very difficult to push in)?

 

Thanks

[llhat]

years go I bought a set of o-rings from local dealer,   there's 12 in a set, don't have p/n presently

 

IIRC 6 were different color from other 6 and i think slightly different in size.

 

The flat OD is from being compressed inside the fuel rail or the head.

I remember lubricating with fuel for insertion.

 

If it was me, I'd probably just replace all the injectors and o-rings (which i think are with new injectors)

ya gotta pull all of them anyway to remove rail for just one....

[Pete M]

I had an injector split on the body and leak.  ended up replacing them all with junkyard injectors from an Expedition. 

[Eagle_SX4]

I agree that over time and all the heat cycles the o-rings will mold them selves to the shape of the fuel rail or intake manifold. The ones will be round.

 

I have used the Fel-Pro (#ES73096) o-rings with great results.

[pizzaman09]

I used a very light coating of a silicone O-ring lubricant to install mine, made install super easy.  If you don't have silicone O-ring lubricant, dielectric grease is nearly identical and will work.  Vaseline would also work.

[75sv1]

The flat edge on the Oring is that it has collapsed and failed. Probably your problem. As has been stated before. If there are two different colors, the black ones go to the fuel rail. The reddish brown ones go to the manifold side. I've used Vaseline previously. Some say petroleum products are not good for Orings. I have been using an Oring grease in the past few years. I bought it at a Ture Value, in the plumbing supplies. 

       I did have an Oring rot on me the past year. I had put 12 hole injector in about 2 years before that. They were rebuilt ones. I do not know the country of origin of the Orings. I did replace them with some Gray-Silver ones from COMETIC. I bought them at Oreily's. Many report rubber parts sourced from China fail early and often. 

[AnotherOldJeepGuy]

Thanks for all the info.  I'll post how it goes, perhaps with some along the way pics to document things for anyone else that might want to see them.  I am supersized Expedition injectors can be used, learn lots from this group!

[pizzaman09]

O-rings should not have flats in them, if they do they have taken a set due to compression and are not as effective as they once were.

 

I would not be worried about using Vaseline on these o-rings, these o-rings are made of a material that is supposed to be resistant to fuel so the petroleum based Vaseline should not effect it.

[AnotherOldJeepGuy]

Good Point.  Fossil fuel = Fossil fuel.

[Pete M]

that's definitely not how that works, but in this case it's fine.  

[pizzaman09]

6 hours ago, Pete M said:

that's definitely not how that works, but in this case it's fine.  

True, but generally the trend is there iny professional experience.  If I really wanted to get technical with it, I'd go talk to the rubber formulators I work with and get them too look up the base polymer for the rubber in the giant fluid susceptibility guide books. 

 

In any case Vasoline is unlikely to damage the o-rings designed for fuel.

[75sv1]

I did open a box of injector Orings last night. They were from NAPA. Possibly, I purchased them 2-3 years ago, or even last year. There some brown ones and some black ones.