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Old 13-08-2012, 09:19   #1
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High Pressure Fuel Lines Leaking at Injector

I just replaced the copper washers at the bottom of my injectors, and now I have a weeping leak at one of the fittings where the high pressure fuel lines connects to the injector with a flare fitting.

I don't know the actual torque specs, but I have it "tight", and it still weeps. One thing I just read, is that using flare-nut wrenches can help since they don't distort the fitting. I'll take the fitting appart, make sure everything is clean and shiny then tighten back up using a flare nut wrench.

Is it common to use some sort of sealant (teflon paste or tape) on the fittings? I'd hate to get some teflon tape in the injector!

The leak is where 11 meets 6.

Thanks for any advice!

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Old 13-08-2012, 09:37   #2
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Re: High Pressure Fuel Lines Leaking at Injector

check your flare --it may be as was mine-- now mine isnt leaky any more--my mechanic fixed it.
will post what he did when he gets to this location--no i did not buy new

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Old 13-08-2012, 10:01   #3
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Re: High Pressure Fuel Lines Leaking at Injector

DO NOT, REPETE do not use teflon tape anywhere in the fuel system !!(don't ask !) and ya might anneal the washers ! as some times they are hard as heck and need it !! then use the proper size flare wrench, should fix it ! just my 2 cents PS do not over tighten the flare nuts as this will crush the washers
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Old 13-08-2012, 18:51   #4
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Re: High Pressure Fuel Lines Leaking at Injector

Flare fittings need to be as straight as possible. There is a tendency to just push it over into alignment and get the b-nut started and then crank it down. This usually works but sometimes doesn't.

You definitely need item 12 completely loose when attaching the flares to the injectors. At this point with a leak you need to determine why the flare is not seating on the injector cone.

First remove the tube and the injector and get to some decent light.

Inspect the flare and the cone of the injector - Any piece of dirt between these surfaces could have embedded.

PS - Also remember there are two parts to the flare fitting. The tube flare that seats against the injector cone and the nut flare that seats against the "outside" of the tube flare. Make sure the nut seats on the flare properly as well and there is nothing contaminating that joint surface.

Also inspect very carefully the shape of the flare - If assembled in misalignment and torqued down a permanent deformation of the flare could have occurred.

Also inspect the flare for a ridge or groove. Sometimes they can take a set especially if overtorqued at some point and now when reassembled they are seating against each other in a different location.

Sometimes you can lap the flare surface.

If this looks good proceed.

There are several "telltale" compounds available. Dykem blue which is like a blue ink. There are brands that are tape as well. Apply the telltale to the injector flare and carefully assemble (so as not to smear the telltale) on a bench or table "hand tight" - Remove and inspect the flare - the telltale will transfer to the flare and you may identify a high spot or low spot although with a leak this minor it may not show up.

They key point is to check for grooves and/or ridges on both surfaces (flare and cone) and then make sure the supporting clamps (item 12) are completely loose and you are not introducing any side stresses while aligning the flare with the cone.

Finally use a torque wrench and a flare fitting wrench. 90% of the time it will work out find but overtorquing is as bad as overtorquing as the flare can be permanently deformed.

PS - Don't forget there are two parts to the flare fitting. The part that seats on the injector and the nut that seats on the "outside" of the flare. While on the bench check the nut is seating properly on the flare and that there is no contamination on this surface.
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Old 13-08-2012, 19:49   #5
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Re: High Pressure Fuel Lines Leaking at Injector

Both the injector pipe and the injector itself are made from very hard steel but I would not recommend exceeding the manufacturer's specification for the torque value.

One trick I've used in the past for determining exactly where a leak is coming from is to spray it with baby powder. The white powder will darken most quickly at the source of the leak.

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