Sourcing new injection tube gaskets

I have been operating with some very minor leaking from the injection tube to the injector for a while but now that the temperature is dropping I believe the seals are contracting even further allowing air to get into the injection tube overnight leading to rough morning starts.I would love to replace the gaskets/seals only if possible but haven't the faintest clue how to determine the appropriate material/size. If this isn't possible, I *can* source some new injection tubes but those are obviously going to be a bit more pricey.Any suggestions?

Only "seals" i am aware of are the copper crush washers

Normally the injection lines, pipes, do not leak. Both ends are compression fittings. Try tightening them. Does the engine smoke when first started? If so with a white smoke you might have a bad injector leaking off after the engine is shut down which will allow air into the line.

I'm not sure what copper crush washers you're referring to, but I finally did get a chance to disassemble some of the injection system. Beneath the fuel return pipe is a little gasket with two holes in it. While I didn't see anything that looks out of the ordinary, the fuel return pipe assembly was quite the pain to remove. It may be bent enough not to sit flush, so I might pick up a replacement next time I go salvaging.


The copper crush washers you refer to I assume are between the injector and the block?

I was told that the 83' 4d55 heads used a different injector which uses a unique crush washer between the injector and head. They were all but impossible to find to purchase. I was able to track down a set from a member on this forum.

I'd have to look at a manual to be completely certain but I think you are right in that the copper washer is between the injector itself and where it screws into the head. There are those little return washers that are aluminum and have the two small holes in them and they sit between the injector and the return line as you already discovered.

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Originally Posted by Uncle Spence

I'd have to look at a manual to be completely certain but I think you are right in that the copper washer is between the injector itself and where it screws into the head. There are those little return washers that are aluminum and have the two small holes in them and they sit between the injector and the return line as you already discovered.

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Right, during some inspections yesterday I was able to determine that the leak(s), as far as I can tell, are between the aluminum return washers and the return pipe *and* between the return pipe and the nut holding it onto the injector.

My current hypothesis is that my fuel return pipe is bent and is not sitting flush on the injector return gaskets. This is corroborated by the difficulty I had in prying the damned thing off when I was inspecting the injectors this weekend.


I'm wondering if I can apply a little bit of sealant around the nuts or if I should just try to source a new fuel return pipe :-/

Quote:

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Originally Posted by frankwrench

Right, during some inspections yesterday I was able to determine that the leak(s), as far as I can tell, are between the aluminum return washers and the return pipe *and* between the return pipe and the nut holding it onto the injector.

My current hypothesis is that my fuel return pipe is bent and is not sitting flush on the injector return gaskets. This is corroborated by the difficulty I had in prying the damned thing off when I was inspecting the injectors this weekend.


I'm wondering if I can apply a little bit of sealant around the nuts or if I should just try to source a new fuel return pipe :-/

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This hypothesis was incorrect. After cleaning things up and re-installing the fuel return pipe, tightening it along the way, I was able to identify fuel pushing out between the fuel return pipe and the nut which holds the pipe onto the injector assembly.

Upon further inspection it looks like the nuts may have been over-tightened in the past, leading to some scoring on the fuel return pipe's nut-portion.


I'm contemplating fitting crush or silicon washers between the nut and the fuel return pipe to enforce a stronger seal. Thoughts?

pull it off and file it smooth and smooth i with sandpaper on a block

I ended up removing the injectors and re-tightening those with my torque wrench to spec, re-seating the fuel return pipe and placing some M12 zinc washers between it and the fastening nut. I then tightened that to spec as well.

The washers combined with a good proper tightening of the entire series seems to have resolved the dribbling leak issues I have seen.

If I can find some of those copper crush washers I will still gladly install new ones however.