Splicing a diesel injector line??

550Doug · Nov 19, 2013

The American Bosch PSB pump on my Hercules 298D motor has 6 injector lines from the pump head to the 6 injectors, and one is leaking at the pump head because of a bad ferrule. I have a good injector line from a Hercules 339D motor but it is considerably longer than the leaking one. Is it possible to cut off about 8 inches of the good line and replace the 8 inches of the bad line by doing a splice of the steel lines? Will the pressures inside the line cause failure at the join? Has anyone tried something similar?
Thanks in advance

Bob · Nov 19, 2013

WHAT did you intend to splice it with?

I've seen several attempts to do what you are proposing, all without success.

D7fever · Nov 19, 2013

I've got a spliced injector line on my D7, that was
done before I got it. Runs ok. You could try it, if
it works ,great. If it doesn't work you are just out
your time.

jm. · Nov 19, 2013

Doug usually the greater issue than the mechanical weld or splice is engine timing. Injector lines if you will look an a certain engine are ALL the same length. This is don by adding curls or what ever to get the lines all the same length You would have to get very close to the same length. I like the others have seen many attempts and most were failures. I have seen a few braised where their was a small rub hole.

John T · Nov 19, 2013

Some of that reinforced plastic tubing and a couple hose clamps wont work huh GEEEEEEEEEEEEE theres goes my Billy Bob fix lol lol

John T NOT a diesel or high pressure kinda guy

Tx Jim · Nov 19, 2013

(quoted from post at 09:01:06 11/19/13) Doug usually the greater issue than the mechanical weld or splice is engine timing. Injector lines if you will look an a certain engine are ALL the same length.

jm
Although I wouldn't advise splicing an inj line I think they're not all "exactly the same length". I do understand the purpose of the extra bends/curls in the inj lines. I'll post a parts photo of a JD 4020. Parts key #1 weighs 0.51 lbs while parts key #7 weighs 0.46 lbs. I agree that weight isn't length but there's definitely more material in one line than the other.

jimg.allentown · Nov 19, 2013

Not advisable. First, contrary to what was previously stated, the lines are all the same length. This is done for injection timing, and it does make a difference. Secondly, the lines are under quite a high pressure. Splicing will usually fail because of failure of splicing materials not being able to tolerate the high pressures.
Having said this, the recommendation would be to purchase a new line. It will save you untold aggravation and problems.

Bus Driver · Nov 19, 2013

If I was going to splice it, I would make a sleeve that fits snugly then insert the lines into the sleeve and silver solder.

JAG from mn · Nov 19, 2013

I've done this before, you need a larger tube that just slips over the injector tube. Sand everything to bare metal including the ID of the larger tube. You need to use silver solder with silver solder flux. You need to use an acetyline torch with a small tip.It's kind of like brazing so practice alittle. Silver solder is extremely strong and is used alot in the refrigeration field.

El Toro · Nov 19, 2013

We used Swagelok stainless steel fittings. They won't leak. Hal

jon f mn · Nov 19, 2013

I spliced all 6 lines on a pulling tractor I did
years ago to make them longer so they would reach
the other side of the tractor. I just cut equal
lengths from both halves and welded them together
and presured them with air to check for leaks. Still
running as far as I know and that's been most of 20
years now.

Bob Bancroft · Nov 19, 2013

Once again, you're right on top of it.
Is it just me, or are there more and more experts on here who declare everything with absolute certainty?
On my early 4020, it's obvious that no effort was made to make the lines the same. I asked someone about this once. They said, "once the lines are full of fuel, what difference does it make"?

Dieseltech · Nov 19, 2013

The fitting you need is Ambac part SV 7922, or Weatherhead 7165X4. The sleeve is loose on the line until the nut is drawn tight. Maybe you can repair the old line, or shorten the longer one to fit, with no spliceing. The PSB hydraulic heads are too hard to find to risk with a spliced line. I put a model 100 Ambac pump on a 570 this past summer for a puller, and made the lines up with the sleeves as needed.

Dr. Walt · Nov 19, 2013

John T.:

Surprised you didn't try to replace it with ROMEX. LOL

John T · Nov 19, 2013

Wellllllll maybe not Romex, but heck Armored Cable MC now that's pretty strong stuff ya know provided its grounded lol

John T

DENNIS MIN · Nov 19, 2013

Bob Bancroft,

Your response about when the lines are full agree with the little hydrodynamics I have learned.

D.

Bob Bancroft · Nov 19, 2013

I was just thinking about this. I suppose there might be an infinitesimal amount of compression of the fuel, and a likewise amount of swelling in the line, that would effect timing. I'm guessing these amounts would be so tiny that it would make just as much sense to make spark plug wires the same length!

DENNIS MIN · Nov 19, 2013

Bob Bancroft,

Theoretically, yes. And thanks for getting me to shake the dust off old learnings...

In my opinion, at the temperatures and pressures of older injections systems, the length differences in the lines, the incremental increase of line volume, the speed of the crankshaft....well, you probably get where I am thinking.

D.

DENNIS MIN · Nov 19, 2013

El,

We used those swagelocks in the Navy. The splices hydrostatically tested in the thousands of PSI.

D.

El Toro · Nov 19, 2013

We never had one of those fittings to leak. We ran brake tests on wheel vehicles for the Army and we would cut the main brake line and install one of those tee fittings so we could measure brake pressure. I think we tightened the nuts 1-1/4 turns. They came in an assortment of sizes.
Hal

El Toro · Nov 19, 2013

Swagelok even has weld fittings for splicing. You can use silver solder. Hal

DENNIS MIN · Nov 19, 2013

El Toro,

We, too, had used the swagelock fittings for many hydraulic connections without failure.

If I remember right, there was a block, that was used to make up a fitting. It required dry graphite, and when a certain draw-up was achieved, an additional partial turn dependent on tubing size was required.

D.

Splicing a diesel injector line??

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