Injector HP Fuel Line - How to Make?

[Wotname]

I have Yanmar steel injector lines and I wish to make new ones.

How are the ends fitted to the steel line?

Where can new ends be sourced (if needed)?

It looks like the ends are brazed on the steel tube; if so, can the existing ends be removed and refitted (i.e. brazed) to the new tube /pipe. The existing lines are 6mm OD.

I could just try to remove them but I thought it might be quicker / easier if I knew beforehand how they are normally constructed - a little knowledge can be dangerous , but more knowledge is helpful .

[ulpilot45]

Originally Posted by Wotname

I have Yanmar steel injector lines and I wish to make new ones.

How are the ends fitted to the steel line?

Where can new ends be sourced (if needed)?

It looks like the ends are brazed on the steel tube; if so, can the existing ends be removed and refitted (i.e. brazed) to the new tube /pipe. The existing lines are 6mm OD.

I could just try to remove them but I thought it might be quicker / easier if I knew beforehand how they are normally constructed - a little knowledge can be dangerous [emoji3], but more knowledge is helpful [emoji2].

The ends are silver solder ends like with jeweler's use ready of North America sells a replacement ends and line

[Wotname]

Silver soldered, OK that's good - makes it easier!

[kmacdonald]

I thought most were swaged. I could be wrong.

[Wotname]

Originally Posted by kmacdonald

I thought most were swaged. I could be wrong.

Maybe they are these days - mine don't look swaged but they are old - say 40 years old.

[model 10]

I've made a number of fuel injection lines, you silver solder them. Re-use the old ends.
Don't imagine making perfect bends, this will be a pain.

[kmacdonald]

From what I've seen, silver solder is a temporary fix.

If you do decided to go that route, be sure to use the correct flux. They are toxic so be careful. Don't forget to clean all the slag off so and injector doesn't get plugged.

The length of the line matters.

[EngNate]

Yes, line length matters, as does I.D. and wall thickness. I'd buy the OEM replacements if performance matters.

[jimbunyard]

Yours look silver soldered or brazed, both of which are undoable but you need an oxy/gas torch to do it right. You also need to be able to clean the old ends of enough residual metal left inside after removal to get the new pipe to slip inside. They have brushes for this but it may be easier to just drill them out with a closely matching bit.

Do not clamp the ferrule in a vise, the heat likely required to remove them is going to be just about the softening stage of the steel itself, if they're brazed it'll be well into the softening stage, about a dull cherry red probably. Cut the line in half (or wherever), clamp the cut end in a vise with the box end of an appropriately-sized wrench around it, and when you get the ferrule hot enough, pull it off with the wrench.

Red hot metal produces 3rd degree burns almost instantly...

Cleanliness is of absolute importance when resoldering/brazing. Fine sandpaper followed by an acetone wash is necessary, as well as the correct type flux.

Practice would be nice, perhaps you could drill out some steel hex nuts to 6 mm and use them and some of the tubing you're replacing as guinea pigs...

Found a few places online for replacement ends, but this is likely a place where you need to have personal communication, either a phone call or a visit to the local injection shop...

New lines are available, but the place I found wants 80.00 US each for an unbent one. (you have to bend it yourself) Oddly enough they also had a new (aftermarket) head casting for your engine for (only) 800.00...

[ulpilot45]

Originally Posted by ulpilot45

The ends are silver solder ends like with jeweler's use ready of North America sells a replacement ends and line

Silver solder ends are good for the life of the line been making lines 40 years in the business of pump rebuilding but if you can find replacement one is the best way to go. If not redat also sell a bending jig to make the line look like factory

[Wotname]

OK, thanks everyone!

It sounds quite doable - I have done enough silver soldering over the years to handle this job - I wasn't sure if this was standard practice but it sounds like it is.

Bending won't be an issue, I have bent enough tube in the past to handle the three 90* bends, one 180* bend and one 45* bend. I have the old rusted out ones to copy from to get the bends and the length right. I'm sure I will find suitable tube.

If it all turns to custard, the local injector shop can make them up for me but really it shouldn't come to that.

[svthreecheers]

Originally Posted by Wotname

I have Yanmar steel injector lines and I wish to make new ones.

How are the ends fitted to the steel line?

Where can new ends be sourced (if needed)?

It looks like the ends are brazed on the steel tube; if so, can the existing ends be removed and refitted (i.e. brazed) to the new tube /pipe. The existing lines are 6mm OD.

I could just try to remove them but I thought it might be quicker / easier if I knew beforehand how they are normally constructed - a little knowledge can be dangerous , but more knowledge is helpful .

Don't forget to re install all the clamps on the high pressure lines again to keep them from
vibrating !! Number one cause of cracking steel lines.
Different length,inside and outside dia.will change the fuelquantity injected.
Make sure the ends ( nipples ) fit the new line ( 6 mm or 1/4 " )
Please silver solder only,brazing won't last very long
How do I know? 45 years fuel injection.

[Wotname]

Originally Posted by svthreecheers

Don't forget to re install all the clamps on the high pressure lines again to keep them from
vibrating !! Number one cause of cracking steel lines.
Different length,inside and outside dia.will change the fuelquantity injected.
Make sure the ends ( nipples ) fit the new line ( 6 mm or 1/4 " )
Please silver solder only,brazing won't last very long
How do I know? 45 years fuel injection.

Thanks svthreecheers and that's a lot of experience to call on

I'm curious, how does the OD change fuel quantity - assuming the ID and the nipples remain the same (and the wall is sufficient to handle the pressure)?

Also I am assuming the length is most critical in so far that all the lines should be the same length. The routing between the injection pump and the injectors pretty sets the desired length and the curves / bends ensure equal lengths.

These questions are not really related to my current job as I already have the designed dimensions to work with i.e. copying the old lines (and there only two of them).

[Lepke]

Think of the injector line as an assembly line with a series of fuel loads making their way to the injector. Each time the engine fires the fuel moves a small amount in the tube. Small differences in tube length or diameter won't make a difference. The reason the tubes have to be bled is air in the lines compresses instead of moving fuel along. The injector has a spring loaded valve that opens by pressure. Air in the tube, injector doesn't open.
Considering tube cost, I can't see making my own.

[jimbunyard]

Originally Posted by Wotname

Thanks svthreecheers and that's a lot of experience to call on

I'm curious, how does the OD change fuel quantity - assuming the ID and the nipples remain the same (and the wall is sufficient to handle the pressure)?

Also I am assuming the length is most critical in so far that all the lines should be the same length. The routing between the injection pump and the injectors pretty sets the desired length and the curves / bends ensure equal lengths.

These questions are not really related to my current job as I already have the designed dimensions to work with i.e. copying the old lines (and there only two of them).

Hope nobody gets their panties in a wad here, but technically soldering or silver-soldering is brazing, i.e. the process of joining two or more pieces of metal together with a filler metal that melts at a lesser temperature than the metal being joined.

It is troublingly common on internet discussions for people with lots of experience to make declarative statements, with probably/usually good reasons for making them, and then stop dead, with no explanation and no information as to how to accomplish the job in the way they deem correct.

For instance, I know there are at least dozens of types of 'silver solder', probably hundreds, not counting those that are the same alloy but produced by different manufacturers. It seems to me that at the very least it would be helpful to include some kind of designation as to what alloy or brand or designation of which product years of experience has taught works best, as well as maybe a brief note regarding technique.

The 'length issue' with injector lines has always been a little mysterious to me. To begin with the OD cannot, by definition, affect the amount of fuel injected, unless it is either so thin that the injection pressure expands it, which to my inexperienced mind would cause it to fail, rather sooner than later, or if the wall was so thick that it increased the length, which would of course mean that the length was what was causing the difference.

But back to the point about the length...imagine that you have two tubes, 1/2" ID, each filled with 7/16" marbles, one ten feet long, the other one foot long. If you push (inject) one more ball into the end of each tube simultaneously, a ball will be ejected from the other end of both simultaneously, regardless of the length.

Thus, I can only come up with two potential reasons for the 'all lines must be the same length' rule (which I always dutifully quote when asked).

The friction in the lines is enough to make a difference due to length (more length=more friction=different pressure), or the different volume in different length lines acts as a kind of accumulator, and allows a slight variation of pressure based on those different volumes, or a combination of both.

Or it could be something I've missed entirely.

It would be interesting if someone familiar with fuel injection theory could actually explain the real reason(s) clearly and conclusively...