injector strategy

[TylerDurden]

I wouldn't worry about the IP losing pressure when sitting, it's supposed to... If it didn't flow fuel through the tiny orifice in the out-bolt, the IP would overheat.

I've seen some good gauges, but $$$ unless you find a yard-sale treasure. I think I used a cheap gauge, got me in the ballpark.

I brazed the fittings on my DIY popper... easy peasy, or at least better than my crappy welding.

[greg lousy]

I like the filter addition.

I should have been more specific -I think my pump loses pressure by letting in some air - too much play in the main shaft... air in the line, visible tiny bubbles in return line shortly after start up, but after a minute no bubbles. I don't need to get into this now though - I've only recently permanently installed a clear return line, so I'll get back to this once I'm more sure about this situation, and do some of the ingenious IP tests I've read about here.

For now I've been soaking/ cleaning, resoaking, recleaning all my injectors. I haven't measured precisely with feeler gauges but at a glance the spring/ shim protusion from the top part seems the same in the suspect injector as the others (the worms are getting along quite well) - when I put them together I'll measure the turns as suggested and see what I find.

Also noticed that one of my injector top halves is labelled 130 bar and the others 155 bar - I'm assuming that they are, as they seem, exactly the same but the one is labeled for NA use and the others for turbo so this shouldn't matter, right?

... I found some used fittings sold in a clump on Ebay and ordered them with my eye on the IP/ pop tester conversion idea... we shall see

[TylerDurden]

Also noticed that one of my injector top halves is labelled 130 bar and the others 155 bar - I'm assuming that they are, as they seem, exactly the same but the one is labeled for NA use and the others for turbo so this shouldn't matter, right?

Well, the 130 would be a timing issue for that hole... If it is actually sprung/shimmed for 130, it will open earlier.

[Fatmobile]

A little air coming out of the pump at startup could be a leaking small line between the injectors, letting air in as it sits.
Clear lines on those small barbs too, at least the one going to the pump.
A mainshaft seal leak will often send a bubble back out the intake of the pump shortly after shutdown, because it's internally tied to the front of the pump so behind the mainshaft seal is at the same pressure as the front of the pump.

[greg lousy]

did some measuring with my cleaned injectors

the spring/shims were very close, all about 1.09 - 1.2 mm above the top injector part - close enough to put my own error larger than any answer
- the turn test, also very close, but consistently high - each about 440 to 450 degrees from spring contact to 52 degrees of torque, and again, the difference probably falling well within the range of my own error

according to JHH's numbers, this would put them at something crazy, like 185 bar... would the springs lose that kind of resistance over time? compensating for this?

anyhow, while I am wondering if this, along with the 155 bar labels may suggest these injectors were calibrated to turbo specs, I'm basically thinking that I can't really nail this part of the diagnostic process without a pop tester, which brings me full circle....

my local diesel shop charges $15 a pop, then $90 an hour for calibration ... in other words, about the price of a pop tester.
I may buy one or make one... anyone know offhand the size and thread of the injector line unions? My gamble on random Ebay fittings didn't pay off... though I'm sure they will someday come in handy. got a little more breathing room now, with the tax refund

Messing with the IP is surely in my future, and I'll check out the little between injector lines, but I'd like to get one part of the equation solved before moving to another part

[TylerDurden]

Hidden behind my little fuel filter is an old delivery valve shell, from a parts-pump. I brazed that to a fitting that joins the tee.

The delivery valve shell lets me hook up a standard injector line. If you don't have a spare line, you can use one from the car.

[greg lousy]

still thinking about the pop tester but in the meantime I put the injectors back on today. I was going to see what I could do tweaking the injection timing and then I was going to measure pump outflow and compare to the specs generously provided on this forum.

I say "was going to" because now its not starting or firing at all - I measured to IP timing just to make sure I was in the ballpark and I was... and I was moving it a little as I was trying. It looks like the problem is that the injectors, at least two of them, are leaking from where the upper and lower halves screw together - pretty clear - bubbles rising through the little rings of diesel around the area.
what can I do about this without altering the torque?

[Quantum-man]

It looks like the problem is that the injectors, at least two of them, are leaking from where the upper and lower halves screw together - pretty clear - bubbles rising through the little rings of diesel around the area.
what can I do about this without altering the torque?

Try undoing each of the 'leakers', in a vice, and dong them back up to a lesser torque a couple [or three] times, and then final torquing. This will mate them back together a little; maybe enough...

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Here is a link to the pop tester I built with parts list and thread sizes

viewtopic.php?f=8&t=771&start=60

[greg lousy]

I think they're all leakers - diesel around them all - just noticed the bubbles in two... damn -

Try undoing each of the 'leakers', in a vice, and dong them back up to a lesser torque a couple [or three] times, and then final torquing. This will mate them back together a little; maybe enough...

... well, its a rainy day tomorrow anyway - here's a preemptive question - thread lock just feels like a bad idea to me, but if they keep leaking..... anyone have any experience with this?

AD thanks for the fitting info... may put it to use. For now my priorities have kind of gotten more basic... trying to get from A to B now... this is... albeit insanely... my only vehicle

[82vdub]

Are you sure that the leaky diesel is coming from the threaded half of the injector body and not the injection line nut? Did you seat the injector line to the injector by pushing down on it to center it on the injector, then tighten the nut? If you just crank down on the nut, sometimes the lines will not seat properly and the connection will leak. Just an idea.

[greg lousy]

Much has occurred. Put my injector lines on backwards again... I've been testing and messing around. Basically it appeared that my injectors weren't breaking, and this caused a big messy situation with the injector return system dealing with all of the fuel. Leaks from the little lines... air getting in... some fuel working through the injector body.

The part called the nozzle holder (between the nozzle and upper injector body) had looked questionable in all injectors so I suspected that the channels to through the injectors simply weren't sealed. Sanded them down to clean metal with 600 grit paper, put them back together... and now, still with the injector lines on backwards, I've got one injector that sprays good, one that sprays all awkward, one dud, and one whose shim I dropped, apparently into another dimension, so I don't know about that one. I have a guy who probably has nozzle holders.. the sanding was more diagnostic (though if it worked great... I probably would have left iT).

I'm thinking the nozzle holders had some crud and wear, possibly even connected to my oxidized IP disaster of a few years back. Disassembly and cleaning messed things up and Sanding them down made the situation better, but still not functional.

Pop tester should be finished soon. This is on the cusp of becoming personal. In the woods a bit here but OK... sure putting a dent in my screw up quota. As always, any thoughts/ insights appreciated

[greg lousy]

Got New injectors on the way, along with the last piece I need for the pop tester. All of this deconstruction and cleaning and thinking has been more about my own learning than the good of the ole caddy, and she deserves better. Also, the more I look into this, the more messed up I think my injectors were, before and after this process (well, especially after). Besides, I've been watching the spray all this time never having even seen it from an injector I know is good.

Anyhow, for the pop tester, if anyone's got an old union and/or injector line they would be willing to trade or sell, PM me. I've got a bolt I intend to drill through but an old union would sure be better.

[Quantum-man]

I think 600 grit, should have been 2000...

[greg lousy]

after seeing the results, I think your probably right