Nozzle pics and questions

[jolotter]

I swapped the nozzles in my 1.6 TD today.  The old nozzles were marked SD293 while the new GTDs from Smog were marked SD274.
Anyone know what the SD293 is?

Here's some pics

oldnozzle



New nozzle


The old pintle has quite a bit of scoring around the largest taper.  One of the injectors was dripping at pressure and I'm sure that is why.  Otherwise the tips seem in good shape. What part wears to cause the poor spray pattern?  Is it the opening in the nozzle body?

When I reassembled the injectors with new nozzles, they all opened at about 2100 psi with their original shims.  I can only get about 25psi accuracy with my gauge.  That is a bit high, and higher than I recorded them opening before the nozzle swap.  I made my pop tester out of a grease gun as I saw illustrated on this and the VWdiesel forum and I have fine tuned my pop tester technique over the last few days, using a slow stroke to get the pressure up as high as possible before they blow it all out.  

The Bentley says :

"Note
All new and rebuilt injectors have settling effect of approx.  5 bar.  When installing new/rebuilt injectors, they must have a 5 bar higher opening pressure."

5 bar is about 70psi.

Does installing new nozzles count as rebuilding? What part settles?  The pintle in the nozzle?  The spring on the shim?  By my (fingers crossed) reckoning injectors at  2100psi should settle to 2030psi which is barely over spec.  I'm going to be running heated SVO.  Will this be ok at this pressure?

I was so happy when they pop tested all at 2100 without changing shims.  The VW dealer said 5-10 days to get replacement shims.  Three of the current ones measured 1.80mm and the fourth measured 1.85mm.

Unless any of you gurus out there warn me off, I will use the injectors as is.

edit:  The above numbers referred to the Vanagon Bentley.  I just checked the  Jetta manual.  It  says opening pressure is 2248 to 2364 psi or nearly 400 psi higher than the vanagon VA specs.

Well that changes everything.  I guess I'll go shim shopping.  Even so, the one injector with the 1.85mm shim will only get another 140psi with the thickest shim.  To get 2360 I need another 260 psi.  I can get 210psi with another 0.15mm Can I stack two 1.00mm  shims to get that?
Or does this mean my springs are beat?  :(

[Gearhead]

Where did you find that info on building the pop tester?  Where did you get your nozzles?  I've searched everywhere I can think of.

Thanks,
Don.

[jolotter]

Don, I found the pop tester info here.
http://www.schumanautomotive.com/forums/showthread.php?t=3667&highlight=tester

There are also people that have used a bottle jack for the same thing, but welding equipment, which I lack, is necessary.

I built mine almost the same as the one described in the link except the 18" hose comes out the right side and loops through the stand to hang just out the left side at the perfect height for injecting into a jam jar.  I also soldered the compression ring onto the injector line as it's pretty slack with nothing and I was able to visually inspect that it was a solid mechanical connection.   Not that I'm saying it's better than the JB Weld, just another imperfect way to do it.  Another idea I had was to build a plexiglass box that just the handle would extend out of to protect the user from ruptured fittings.  

*Please heed all warnings about high pressure diesel fuel under your skin and realize that amputation is the only cure.  Look at some of the gruesome pictures available before you try it and remember that you do this at your own risk!*

I did my tests with veg oil.

I got my nozzles from Smog in the vendors section of this forum.  They arrived the day after I ordered them.:D

Andrew,
you wrote:

I like to get thicker shims than necessary and fine tune the breaking pressure by sanding the spring down a little at a time.

Did you mean sand down the shim?

I realized my error in using NA specs.  I've been using the Vanagon manual because it's format is more user friendly, including separate sections for the diesel engine and torque values right on the diagrams.  I normally have them both open, hogging bench space.

Anyone know what that SD293 nozzle is from?

[jolotter]

Where do you get your steel flare fittings, Andrew?

Johann

[Vincent Waldon]

A few random points about how I do this:

- my bottle-jack based pop tester is made entirely of steel hydraulic fittings and an actual steel VW injector feedline... the use of anything else is risky at best imho

- yes, sand the spring rather than the shim... way easier to hold onto a spring as you are lapping rather than a tiny little shim.  The spring is not a sealing surface so coarse  sandpaper can be used.

- I recommend using the fuel you intend to burn as the fluid you pop test with... different oils have different viscosities and this will impact both the spray pattern and how the nozzle pops.

- this is obscure I know, but the "official" instructions specifically warn against touching the pintle shaft with bare hands... evidently skin oils and acids easily degrade the precision metal plating on the sides

- in general, and especially if the injectors have a lot of miles on them, there are three sealing surfaces that can be lapped for a perfect fit.  I'm mere days away from posting a pictorial HOW-TO on my web site... in the meantime here's some pictures that show the general process:

http://www.flickr.com/photos/vwaldon/892675602/in/set-72157600995498533/


Here's a teaser... the  bottom of the top injector half can wear in like this:





Just the way I do things...


Vince

[Gearhead]

jolotter,

Thanks for the info.  That's what I was looking for.  I don't see why, if DONE PROPERLY WITH PROPER FITTINGS, the grease gun tester is inherently more dangerous than the bottle jack style.  At least with a grease gun, you have a pump that is designed for high pressures, and you're not plugging a relief port as you are in the bottle jack design.  

Your link saved me tons of searching.  I'd searched this and another forum for about an hour each.  Then wasted another hour searching this one again after Andrew told me the info was here.  Your thread was helpful, and I eventually found more info on biodiesel.infopop.cc.  

I'm in the automotive field, and have worked with hydraulics up to 10,000psi. for some years.  I understand that there are inherent dangers in any DIY automotive project, and these dangers increase exponentially when improper parts are substituted.  That said, the warnings are enough and will be heeded, and I don't need somebody deleting threads because I might hurt myself.  That's survival of the fittest IMHO.  Rest assured, no part of my body will be any closer than the pump handle until the pressure is relieved.

Now, I have an extra set of injector lines, but I hate to cut them up to make a tester.  

Don.

[subsonic]

"Then wasted another hour searching this one again after Andrew told me the info was here."

 
One thousand one, one thousand two.............

[OM617]

You should NEVER handle the nozzles with your bare hands. The oils in your skin contain acids that can damage the unprotected surface of the nozzle.

[Gearhead]

"Injector and tester" yields 46 threads.  Some up to 22 pages.  As does "+injector +tester" which is the manner I normally search internet forums.  I don't see a way to search a separate "archive."  I'm sure that is an oversight on my part.  I will spend some time looking for the archives.  I apologize for any inconvenience I may have caused or shortcomings I have in using the search feature.  I honestly prefer to search and find the answer myself rather than ask a question and get reprimanded.  At least I wasn't asking what color to paint my brake calipers.  :lol: I understand that my low post count doesn't reflect the 8 mos. of reading every new post and feverishly scouring these forums for information.  I also understand your frustration with newbies coming around and asking the same questions over and over, but some people have put forth quite an effort, and a link to point them in the right direction might be more helpful than to tell them to search more, and it may even aid in the flow of information around here.  I apologize for rubbing you the wrong way, Andrew.

As for the assertion that there is no way to relieve the pressure when using a grease gun, a needle valve on a T at the outlet of the grease gun with a line running back to the reservoir should release pressure without having to break a fitting.  McMaster Carr has a carbon steel 5000PSI unit for $16.  It's basically the same way the bottle jack is relieved, except it's external.  Another thought, a check valve (with a bypassing needle valve) at the entrance of the gauge will hold the needle at the maximum pressure attained by the rig.  

My main reason for wanting to use a grease gun is you start with a proper NPT fitting.  It doesn't hurt that I work for an automotive lubrication equipment company.  Grease guns of many variations are at my disposal.    I just wanted to know how one gets from a NPT to a Bosch fitting.  I don't like the compression fitting idea.  Nor do I want to cut my spare set of lines.  I might just buy a tester for those reasons.   However, one advantage that the bottle jack style may have is a larger piston displacement, depending on the model chosen, but my mig was borrowed by an acquaintance, and currently needs $125 worth of parts to get back up to speed.  I'm not sure I want to fix it right now.  People might want me to weld things... :lol:

[MikkiJayne]

While we're talking about nozzles, if I'm replacing the nozzles on my 150k TDI engine will I need to change any shims or springs in them? Do I have to pop test them or can I just fit the nozzles and stick them back in?
 
Will I have to do the lapping procedure as shown in Vince's pics?

Thanks all

[jolotter]

Andrew,  I appreciate the urgency with which you advise the use of steel fittings and will upgrade my pop tester with them before I use it again.
My grease gun has a built in pressure release.  When I fully depress the handle it allows the grease/oil/diesel fuel to flow back through the circuit.  It depressurises from 2100 to 100 psi in less than a second and most of the rest of the way to zero within another five or so seconds.  When I open the injector fitting, I get a small overflow which dribbles down the injector into the jar.

Nice rebuild pics, Vince.  I'll be lapping those parts and sanding my springs to get a precision break pressure.

Do you spring sanders set the injectors to the upper end of the "new" range or is it just important to have them equal,  so long as they are within the spec'd range?

Johann

[Vincent Waldon]

While we're talking about nozzles, if I'm replacing the nozzles on my 150k TDI engine will I need to change any shims or springs in them? Do I have to pop test them or can I just fit the nozzles and stick them back in?

TDI nozzles are a completely different beast... don't have any experience with them personally... but someone else may well chime in.  

If not, perhaps pose your question on the TDI side of the forum, or at www.tdiclub.com ?



Vince

[Vincent Waldon]

Nice rebuild pics, Vince.  I'll be lapping those parts and sanding my springs to get a precision break pressure.

Do you spring sanders set the injectors to the upper end of the "new" range or is it just important to have them equal,  so long as they are within the spec'd range?

Johann

I generally aim to get them very equal as opposed to an extremely precise absolute number... so I'll assemble them, give 'em a quick test to make sure they are all within the ballpark (150-155 bar for TD ones for instance) and then sand them down to the lowest one.  I don't have a supply of shims yet so this works well.... and I only end up disassembling 3 of the 4.

BTW, my webmaster posted the rough copy of my injector rebuilding notes... still got some work to do but there's a few more pictures and some supporting text:

http://vincewaldon.com/index.php?option=com_content&task=view&id=20&Itemid=28

Everything on the site is pretty broken but it's coming along every day.. next up:  the definitive "timing your diesel" pictorial !!


Vince