Injector line replacement (without removing injector pump)

DaveC

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Hi all--

I have a '94 F350, 7.3L IDI, factory turbo, E40D. BTW, just got it; about totally free of rust; I love this truck! Since I replaced the glow plugs and rebuilt the fried glow plug wire harness, she starts and runs and drives beautifully, even when it's zero degrees. So far so good.

Anyway so now an injection line has I think cracked, right at the point inside the nut where it attaches to the injector. Fuel is welling up upwards from the gap between the steel line and the compression nut ID, so I don't think it's leaking from the return line caps; I think it's the steel line itself that must have cracked. BTW, previous owner didn't reinstall all of the vibration dampers, which seems also to suggest that the steel line may have cracked.

So this weekend, I'm about to take off my air intake, and hopefully replace all of the injector lines in one go. I guess I'm planning to do this without removing the injection pump, which taking that off looks kind of scary.

Anyway to my actual question: Are the compression (or flare) nuts on the injector lines, actually English or metric sizes? The only ones I can easily access at this point are those at the tops of the injectors. And these seem to be 5/8"; but maybe they're actually 16mm, which is very very close? So then the compression nuts on the back of the injection pump would be either some English or metric size, which I wouldn't be able to tell for sure, until I have everything all apart, with no truck to drive me to the store...

Also, from what I read, removing and replacing the injector lines shouldn't be impossible; before I start I'm going to make sure I have a good set of flare nut wrenches; maybe some kind of crow's feet too. However, any suggestions welcome.

Anyway thanks in advance for whatever clues!

--dave
 

Cubey

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5/8 and 16mm is the same thing, wrench wise.

  • 1/16 inch = almost 2mm
  • 1/8 inch = just barely over 3mm
  • 1/4 inch = just barely over 6mm
  • 3/8 inch = almost 10mm
  • 1/2 inch = almost 13mm
  • 5/8 inch = 16mm
  • 3/4 inch = 19mm
  • 7/8 inch = just barely over 22mm
  • 1 inch = 25.4mm
Harbor freight sells flare nut wrenches in SAE and metric and do the job fine, if you don't want to spend a lot. Craftsman ones are good too.

On my RV, I had to use this open ended wrench on one because of the engine tunnel and other things being in the way. The angle the head is allowed me to get in there to it:

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gandalf

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You'll need a 5/8 line wrench for both ends of the metal lines between the IP and the injectors. You'll have to remove all 4 of the vibration dampers. On the IP end work from the top down taking the lines off, and from the bottom up putting them back on. That's the only way you can deal with the bottom lines on the IP. Be ABSOLUTELY sure to put the vibration dampers back on the lines, all 4 of them. You will have to have all the lines removed at the same time. You might want to label them as to which cylinder each serves. This will help in choosing the correct line when putting things back together.

We all understand pictures. Here is one showing the cylinder numbers on the IP. The cylinder numbers are 1,3,5,7 down the passenger side, and 2,4,6,8 on the driver's side, counting from the front.

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Don't hesitate to call for help if the need arises.
 

TNBrett

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I find a 5/8” crows foot flare nut wrench to be very handy for this. But also a standard 5/8” flare nut wrench and a regular 5/8 open end wrench. Sometimes it’s faster with a regular wrench, just don’t use it to break it loose, or snug it up. Also, be sure to hold the timing adapter on the #1 injector with a separate wrench when you loosen the line nut.
 

DaveC

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Hi again everyone, thanks for the replies thus far.

So again, my project is to replace my injector lines, one of which has cracked at its injector compression nut, and now squirts fuel:

Well I think I have everything I should need and the weather looks clear and not as cold for tomorrow, so hopefully I can get all the old lines out and the new ones in all in one day.

A couple of more questions come to mind before starting into this:

1) The timing adapter thingy between the injector and line on Cylinder #1: It looks like the body of this part is gray plastic; the injector line connects down from above this gray body, and just below the gray body there's another hex section just above the actual injector. Is it correct to hold this lower hex section with another wrench while trying to loosen the injector line from the top of the adapter body? The reason I ask is, the adapter body looks to be plastic, and I definitely don't want to torque it some wrong way and crack it, which would ruin my day.

2) My plan is to _not_ remove the injection pump, but rather just to replace the steel lines. (I just got a complete set of lines in, including new vibration damper clamps, from Accurate Diesel.) Once I get the new lines in place, and from reading around on this forum and others, I guess I'm basically planning to leave the injector lines loose at the injector ends, and then just crank the engine, a few seconds at a time to not fry the starter, until fuel comes out at the injectors; then tighten the lines, and try to start the engine. So, question - is that a good procedure for this case? Does anybody have other better suggestions for purging air from the new lines?

Thanks again--

--dave
 

TNBrett

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You are correct about the timing adapter. As far as bleeding the lines, the nut only needs to be about a 1/2 turn loose. More info s ok , but unnecessary. I like to use a remote starter switch for stuff like this because you can be there watching what’s going on, but make sure you have the key on otherwise there will be no fuel coming from the IP. Some folks recommend holding the throttle open when cranking as it may go quicker. 10-15 seconds of cranking at a time should be fine.
 

IDIBRONCO

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It looks like the body of this part is gray plastic;

The reason I ask is, the adapter body looks to be plastic, and I definitely don't want to torque it some wrong way and crack it, which would ruin my day.

You are correct about the timing adapter.
You are not 100% correct about the timing adapter. The entire thing is metal (steel? and brass) like the line nuts are. The plastic piece is only a sleeve/cover. All you have to do is slide it up over the injector line or, if the line is already removed, slide it off of the adapter and set it aside. This cover is not required. I've seen adapters several without it and those engines all ran fine. My guess is that it's purpose is to cover up the brass part of the adapter. that is where we would get our pulse reading for the timing meter that we used at the shop I used to work at. There was a small C clamp looking piece that would attach to that brass part. I believe that the cover is there to keep the brass part of the adapter clean in order to get a good reading.
 

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