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zen bicycle
05-08-2015, 08:48 PM
Hi, It looks like I have a leak on the #1 injector where the "permanent fitting threads into the body of the injector for the HP fuel line to connect to. If that is the case is there a fix to remove and then reinstall the permanent part with some sort of thread sealant?

MillionMileSprinter
05-08-2015, 11:59 PM
The threads don't seal the fuel line. They act to compress the compression fitting. So the permanent compression faces are somehow not sealing. Maybe they are deformed or something. The easiest thing to do is get another metal line coming from the fuel rail. IIRC, all 5 are the same, so getting a few from a junkyard sprinter should be enough.

zen bicycle
05-09-2015, 12:24 AM
To be clear this is the side that screws into the injector. Not the actual fuel line union.
And as a follow up is there any harm in trying to unthread it from the injector body and re-seat it?

MillionMileSprinter
05-09-2015, 04:40 AM
No harm at all. Try to tighten it, wrap the threads with trflon tape, and if neither one works, buy a new injector

Tooth Fairy
05-09-2015, 08:52 AM
buy a new injector

Or a new O ring?

zen bicycle
05-09-2015, 01:59 PM
where would I get a new Oring? I assume it needs to be diesel resistant. Anybody know the size?

Thanks

MillionMileSprinter
05-09-2015, 02:07 PM
Is there an o ring in there? I don't remember seeing one...

MillionMileSprinter
05-09-2015, 02:59 PM
I just pulled an old injector out of a box on my garage shelf to get that piece unscrewed and to see if there was an o ring under there or not. After 15 minutes, all I have is a dinged up injector. Because the shaft is round and the top is somewhat tapered, I couldn't get my bench vice to grip it tight enough to get that piece unscrewed. It is screwd in TIGHT. Maybe yours is loose, so it will be easier, but my injector is too dinged up to use and I never got the piece out. YMMV.
...on second thought, you could do it with the injector still in the engine and the hold down clamp will keep it from moving, but that would put a lot of sideways stress on the clamp and bolt... Maybe not a good idea...

zen bicycle
05-09-2015, 03:34 PM
well, I got it out and now am worried about the sideways stress I may have put on it, but no O rings anywhere in that fuel connection. Funny thing though it did have a flat washer at the bottom. It matched up against the bottom of the fitting, but not the bottom of the hole the fitting went into. Hope it lined up right. A little permatex thread sealant and we will see what happens. Will update once it cures

Aqua Puttana
05-09-2015, 06:58 PM
I believe the injectors can see 20,000 psi or so. Any systems which I have worked on that have extremely high pressures depended upon mechanical seals of some sort. I don't recall any systems that used taper threads and sealant. Are the threads even tapered?

The disk you saw is likely a seal washer of some type which is not intended to be reused.

vic

MercedesGenIn
05-09-2015, 08:52 PM
Hi,

The flat washer is in fact the seal Vic, it butts up between the internal machined face of the injector body (the bottom of the threaded hole) and the machined flat end on the parallel threaded union.

The sealing washer is not a tight fit in the hole (when the union is removed) and looks to be machined and polished hardened steel (to an accurate degree) on both faces, to be honest it almost looks like it really shouldn't be there (it looks like a precision ground 0BA washer!) - but it should. There is some kind of hard loctite thread lock used on the threads, as has been discovered. I would imagine it is a specialist 'factory' gloop and mating surfaces probably have to be 'diesel free' for it work its magic. The thread-lock is potentially more of an anti-vibe solution from the factory than any seal, as this would be facilitated by the flat precision washer and machined surfaces at the union/body mating parts.

These components I am sure can be reused if cleaned purposefully on re-assembly, they are not designed to crush in any way - I have had no problem replacing/re-sealing unions with damaged threads (sometimes damaged by 'billy-bodger' injector removal). Incidentally if you do ever need to rotate an injector to work it out of the hole it is stuck into in the head, the union occasionally causes a problem to the range of swing available. So remove it and plug the hole with either clean rag or a rubber bung - refit it on re-assembly. May be unauthodox but doesn't that apply to most methods of getting the damned things out sometimes!

All the best
Steve

zen bicycle
05-10-2015, 01:29 PM
I saw the red stuff upon removal. Cleaned everything up reinstalled with Loctite thread sealing which should be good up to 10k psi. It looks like that fixed it fingers crossed. As soon as the monsoon season stops down here I am going to do the injector leak test to make sure everything is ok with regards to that. Engine idles smooth and is running what sounds ok for the short test drive I took. Anything else I can check to see if that injector is functioning properly. Most concerned about that washer not being located properly upon re-assembly.