air bubbles in injector overflow lines

[sgnimj96]

I just had my injectors out,   fixed one that was leaking at the halves.     Pop tested em and replaced a nozzle (brazil 293) in the one that was leaking cuz I couldn't get a good spray pattern.   All the nozzles are fairly new.

Anyway, I torqued everything to ~50 as per specs, but I reset and reused the heat shields.

I'm wondering why so much air is pulsing out of #3 injector (the one with the new nozzle)  No external leaks.    Can't find any info on what bubbles in injector overflow lines actually means.     I know some is normal but this #3 is much more excessive than any I've seen.    Could this be the heat shields not sealing well?

I know a lot of people never even see this with standard black return lines.
https://youtu.be/siugn6xt1Yk

[Dakotakid]

For whatever reason, I can't see your video.
Common sense would rule out heat shield....think about it.
Have you tried a different piece of hose?
Is your bleed off nipple distorted or bent so far toward the inj. body that you can't get the hose on all the way?

Those bleed-off nipples are press-fits.....your's may not be sealing well anymore.
It is very easy to distort the bleed off nipples when using a long-neck socket to remove or replace injectors (screwing them in).

But, air from the business end of the injector? No.

[sgnimj96]

I recopied the link.         No one ever complains about this symptom, so I could be way off. 

 Even when I first started it up after priming the lines I noticed steady air bubbles coming out into that overflow tube.

 I have driven the car a bit, took it out on the highway thinking it would clear the lines out.   
 The video was it running cold this morning.
https://youtu.be/siugn6xt1Yk

[fatmobile]

You call that air shoving out through one of the small lines? ha.
I was hoping I could find my picture of an injector pushing air out one of those lines.
 That's just some air vibrating.
 You see all the lines before it are pushing fuel/air down that line too. Farther toward the end of the change the more stuff getting pushed that way.
 The air on the left is passing through the injector top and passing toward the tank.
Give it a chance to clear the line some more.
 The place to look for air getting pushed from the injectors is the small line heading for the pump and the return line getting air shoved into it from that line.

[ORCoaster]

Somewhere along the line I thought I read that the amount of fuel in the small diameter injector lines was the portion not used when the injector fills the cylinder with a shot.  If the pump is pressuring more than needed then you have excess.  That goes to the little lines and back to the tank eventually.  Depending on how good your injectors are you will get more left over after the delivery.  So perhaps the new needle is less generous and you are seeing more running down the tube than the others.

Just a theory and we all know what that means. 

[sgnimj96]

well,  it seems to run ok.       Not much I would want to  change other than those heat shields.    I imagined maybe compression could pass up between the nozzle and injector body with a poorly seating shield.    I sprayed some soapy water at the base of the injector threads, no bubbles. 

Planning a road trip so I want get my skepticism out now 
Thanks for the opinions

[sgnimj96]

 #3 is not like the others...
this was after a 60+ mile cruise  on the highway,  runs good.
https://www.youtube.com/watch?v=6gol3e3Xz-c

[ToddA1]

Years ago, I ran clear return lines with rebuilt injectors. Looked pretty much the same. The lines never completely filled, as I expected them to.

-Todd

[fatmobile]

It looks like it's shoving air to the left injector,.. but I don't see alot of air getting shoved through the brownish line going back to the tank.
 So the line where all the air would accumulate isn't moving much air,
 But it's a dark line and you didn't focus on it much.

[sgnimj96]

yea,  that injector has pulsing air in both over flow tubes but it doesn't really go anywhere.   
  I  took the injector out again,  reset the heat shield and even torqued the injector halves a few more psi.  Took it for a long drive.
No change.   Must be something with that particular Bosch(Brazil) 293 nozzle.   Pop tested it again, doesn't have a very good spay pattern for a new nozzle.   
I'll check it again after a few thousand miles.