My own pop testing thread.

[rabbitman]

I figured I shouldn't clog a good thread with my messing around so I started up over here.

I'm in the process of popping the injectors in my rabbit. I bought 'em rebuilt by bosch in the beginning of 2007.

1. 1800psi, fan shaped spray and sometimes pees pretty bad.
2. 1760psi, peed at first but stopped after a few pumps, sprayed thickest towards where it was peein'.
3. 1800psi, pees pretty bad but once it pops it has a good pattern.
4. 1760psi, sometimes pees but has a pretty good pattern, peed real bad until I pumped hard then it fixed itself.
I assume they should never pee at all.........

So I should put new nozzles in all of 'em? I would also like them to pop at closer to 1900psi, do I need to set them even higher to compensate for break in?

Any advice is greatly appreciated.

[rabbitman]

Is the diesel you are using in your tester properly filtered?  Weird injector behavior can result if it is not really clean diesel.

I was afraid someone would ask that, I got it from the station into a small can that I cleaned with brake cleaner, then from there I put it in a gear oil bottle that I cleaned with brake clean. I also took the jack apart and sprayed it's guts with brake clean. I didn't filter the diesel at all. I suppose that could be a slight problem.............

Just looked at how you put the little filter in there, what's the micron rating of that filter?

PS. I'm gonna come steal that nice big gauge of yours , mine only has 50psi increments .

[rabbitman]

Just looked up the fuel filter ratings.

MK1: 14 microns
MK2: 4 microns
MK3: Didn't list microns
A '98 TDI fuel filter was 23 microns.

The little filter you used, Napa # 3044, was 17 microns.

[rabbitman]

Is there such a thing as a new nozzle that isn't any good? I'm on my 3rd injector and I did it the same as the others, open the little package and drop the nozzle in without touching it or letting anything touch the tip, and it pees.

It gave me extra troubles trying to find the right shim too, my shims jumped from about .064" up to .075" and I only needed one size thicker (about .002"), I ended up opening up some junk injectors to find a slightly longer spring.

It peed the first time I pumped it up but then the second time I sprayed it with brake clean and that seemed to fix it but now after changing the shim a couple more times I just can't make it quit peeing . grrrrr, it's almost midnight too so I'm getting tired and TWICE I almost tried removing the injector before releasing the pressure .

[rabbitman]

Wow this is the pits. I have to drive home in it tonight still. I'm on my last nozzle and it's being a real pain......peein' all over and stuff. I think the factory left some gunk in the nozzles 'cause man they're terrible, sometimes it won't pop at all, just leak all over real bad and gradually get better until it's an ok pattern but then it pees.

[Mark(The Miser)UK]

Wow this is the pits. I have to drive home in it tonight still. I'm on my last nozzle and it's being a real pain......peein' all over and stuff. I think the factory left some gunk in the nozzles 'cause man they're terrible, sometimes it won't pop at all, just leak all over real bad and gradually get better until it's an ok pattern but then it pees.

Just a little pointer...
It is quite possible to overtighten the injector body, so that it actually distorts the nozzle, to the extent that it binds the needle. Try backing off the body torque a smidgeon...

[rabbitman]

Well I've been torquing them to 52ft-lbs but I'll try to loosen them a bit, hopefully that's the case.

I finished at 2AM last night enough to drive home, I did notice lower EGTs at full power.....no more power though. I stopped part way home to make sure I hadn't bumped the throttle linkage and noticed diesel all over the front of the engine puddling everywhere it could. I have two leakers, #3 is really bad so I'll be tearing it back apart tonight.

Maybe I'll try 40ft-lbs.

[Mark(The Miser)UK]

Well I've been torquing them to 52ft-lbs but I'll try to loosen them a bit, hopefully that's the case.

I finished at 2AM last night enough to drive home, I did notice lower EGTs at full power.....no more power though. I stopped part way home to make sure I hadn't bumped the throttle linkage and noticed diesel all over the front of the engine puddling everywhere it could. I have two leakers, #3 is really bad so I'll be tearing it back apart tonight.

Maybe I'll try 40ft-lbs.

A few further points, re leaks, mostly they are from the rubber lines.
Old fuel lines also get tempermental, from being repeatedly given extra little torques, from earlier leaks.
Wipe injectors a few times with paper tissues to be sure or sources. 
A leaking body can sometimes  be improved by undoing and then partially retightening a couple of times.

[rabbitman]

A few further points, re leaks, mostly they are from the rubber lines.
Old fuel lines also get tempermental, from being repeatedly given extra little torques, from earlier leaks.
Wipe injectors a few times with paper tissues to be sure or sources.  
A leaking body can sometimes  be improved by undoing and then partially retightening a couple of times.

Well I wish I'd made absolutely sure it was the body but I just removed the offending injectors. I looked at 'em while it was running and I'm pretty sure they were only wet below the injectors waste line.

I'll put on some return lines so diesel can't run down the sides of the injectors and hold 'em close to the pop pressure and see if I can get a leak that way. Thanks

[rabbitman]

Well I hooked the worse of the two leakers and at about 1000psi it bubbled and spit out the joint , very nice to find the problem quick. I used some crocus cloth and lapped the internal sealing bits and torqued it to 45ft-lbs and that appears to have fixed it. The second leaker took forever but finally a bit of wet showed up around the joint so I did the same to it and so far it's good.

One thing I've noticed is the spray pattern is a lot better after driving it less than 20 miles .

[rabbitman]

I've found that they often tend to leak unless *more* than 52 ft-lbs is used.  I'll typically torque to 60.  Bear in mind that the amount of torque used on the injector halves changes the pop pressure.

Have you noticed any nozzle distortion at 60?

Just a little pointer...
It is quite possible to overtighten the injector body, so that it actually distorts the nozzle, to the extent that it binds the needle. Try backing off the body torque a smidgeon...

Mark, have you verified this? I wonder if as the injector heats up it stretches causing less pressure on the sealing surfaces..........

[745 turbogreasel]

I don't know what my friend was torquing to (or if he measured), but you can crack the body  overtightening too much.

[rabbitman]

That's weird, I just went and without disassembling anything, tried 60, the pop pressure is the same (according to my dinky gauge ) but it peed pretty easy, so I loosened it up and torqued it to 45 and got it to pee twice. Then I retightened it to 60 and it pees easily again.

Now I have to decide if I want them to pee or leak at the joint..............

[maxfax]

I wonder if it could be some variety of issue with the housing..   I had a few that acted the same way.. I shipped them up the road to the diesel shop to be rebuilt and they still leaked, but no peeing..  Grabbed two others and threw new nozzels in them and got it down to one leaking slowly and the other was fine..

[rabbitman]

Are you vigorously pumping fuel through the injectors each time you swap one onto the tester?  You won't get any accurate results until the air is purged.

Yeah I do, especially after messing around half the night and findng one that pees lots, frustration you know.........

Last night I got the leaky injectors to sorta stop leaking, I think they're still wet around the joint so I'm gonna get new little return lines before pulling the injectors again.