Rebuilding injectors

[Rodd]

There is an injector/IP shop near me where I know the lady who runs it and have done a favor or 2 for her. Any way they don't rebuild 6.5 injectors because they are a pain. She is letting me use here equipment to rebuild mine w/ marine tips. Any way I am able to set the pressure at 2300 psi (Knowing that over time it will settle down to 2100 or so) however occasionally when slowly pushing the pop tester arm down it streams instead of atomizes. She said that they need to be lapped more. I have lapped the heck out of them with her lapping stones but they still piss when going slow. Any suggestions from the injector rebuilding god's?

 

[buddy]

Are these new nozzles? What brand nozzles, genuine Germany Bosch or the Herzogg?

Which end are you putting the shims on?

 

[bk95td]

There is a cleaning solution that can be run through them that may cure them[i've read]. I have no experence with it.Otherwise you might try turning the nozzle or pintle slightly so they seat in a different position.
Are you using diesel fuel to test or low viscosity testing fluid? The low visc. fluid may leak past but diesel won't[just a guess]

 

[3500GMC]

Try cranking some fuel through it more forcefully at first, note the pattern, then try the individual 'pops' to check your atomization and pressure.

You develop a feel for the tester, I usually don't creep up too slowly on the pressure, I give a deliberate tug on the handle, not a complete stroke, just a tug. The IP gives quick pulses to in injector, so this logic works.

They should be ok if they're CLEAN, I mean, CLEAN.

 

[6.2 turbo]

When I did my marine tips,they where new off brand, I had to take a few apart and clean them several times before they wouldn't pee before popping. I pop tested a Cummins injector to see how a real injector works,same threads ,and no jerking of the handle needed for these.

 

[buddy]

I was wondering if this is attributable to the cheaper Herzogg nozzles.

 

[nobby]

What 3500GMC said,
There is a reason why the old c.a.v/bryce upright piston style injection pumps are AKA jerk pumps. Atomisation is not wholly dependent upon the injector but also the ability of the pump to supply the appropriate volume quickly. There is a possibility that as it is a rebuild shop test pump then it may be somewhat tired and hence leaks by a wee bit when pumped slowly.

I like to pump up the pump to just beneath cracking pressure and maintain it and then watch for any leakage and then yes give it a jerk to crack off and then check atomisation. On one of my test pumps the larger injectors that I work on will only crack off with this jerking style as in essence that pump is to small for them (bacharach did indeed make a large engine test pump). One particular injector only really performs when you build up the pressure and then physically wack the handle with a hammer.

My guess from your description is that it is streaming at the set pressure and not before. If you have lapped them adequately which it sounds like you have and then they crack off fine when jerked then sounds to me like you are good to go.

Cheers
Nobby

 

[Rodd]

Great advise. Thanks guys. The tips are Bosch with the marine part #. Diesel pro at the place hooked me up w/ them. The fluid used in the tester is viscous. When setting the pressure, what is a good pressure to set at? I know after they get worked a little the pressure drops off.

 

[buddy]

Is the part number SD311 and do they say Germany on them. I dont know if they ever outsourced the SD311s. DieselPro is one of the biggest critics of marine nozzles, surprised he sells them.

I think you were good to start with on the pop pressure, 2300psi. I had mine set to 2350psi, but I havent installed them yet. Just got the install kit with new copper crush washers this week. for the marine nozzles 2200psi was what they were set at stock.

 

[Rodd]

Is the part number SD311 and do they say Germany on them. I dont know if they ever outsourced the SD311s. DieselPro is one of the biggest critics of marine nozzles, surprised he sells them.

I think you were good to start with on the pop pressure, 2300psi. I had mine set to 2350psi, but I havent installed them yet. Just got the install kit with new copper crush washers this week. for the marine nozzles 2200psi was what they were set at stock.

Diesel pro didn't sell me them he just told me where I could get them for $90.

 

[Rodd]

Well I got them balanced at 2200. All is good. It wasn't too bad. The hardest part was guessing which size shim to use first. For anyone attempting to rebuild here is how I did it. I soaked the carcasses w/ internals disassembled in acetone for a day or two then I lapped them and reassembled w/ new tips and tested the pressure. Once I knew the pressure of each injector I was able to guess what size spacer/shim to use to get it to the pressure I wanted. I also used new beveled washer that goes in prior to the new tips going in. One thing I would do differently next time is leave all the internals with the carcass they came from, that way the pop pressures should be fairly close. That is if they were balanced to begin with.

 

[buddy]

That washer in the tip is known as the heat shield, good thing you put it back in.

Did you still get that dripping? Which end did you shim the fuel line end?

 

[bk95td]

You can only shim the inlet end. The nozzle end has a cupped piece the spring seats in. No room to shim there.

 

[3500GMC]

I've had some old used injectors that were shimmed on the fire ring, you could see where the heat was eroding away at the shim. Not good and not a 'fix' at all.

The fire ring is a stainless material and is designed to crush slightly and seal when you torque down the halves. Check them, as they must be tightly sealed to the nozzle and the body. Two contact points toward the nozzle- one to the body. Load the new nozzle and fire ring then use you index finger to squeeze the nozzle down in the bore. Hold it to your ear and shake it, - you shouldn't hear any rattles. One could use a pick to try and scoot the fire ring around also. Should be tight here.

I built a tool to re-dimple the fire rings. Or make them thicker, whatever. Or you can buy new.

 

[Rodd]

That washer in the tip is known as the heat shield, good thing you put it back in.

Did you still get that dripping? Which end did you shim the fuel line end?

I put in new heat shields because the old ones were used pretty good. The shim goes just above the spring. So for explanation purposes starting from the bottom end that goes into engine/head the heat shields goes first then the nozzle/tip, then the little hubcap looking thing (not sure what it is called), then the cap that has a notch for the cylinder on the tip and the opposite side goes toward the spring, and finally the shim/spacer. Sorry no pics.