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-   -   How to build a diesel injector pop tester (http://www.peachparts.com/shopforum/general-information/224334-how-build-diesel-injector-pop-tester.html)

kickit 10-20-2008 01:05 AM

how did you balance the injectors?
 
cornblatt: Is balancing the injectors a matter of changing the width of the spacers until the pressure is correct? Or is there some other magic way :)

Excellent DIY BTY. I think I'm gonna build one.

cornblatt 10-20-2008 11:12 AM

Yes, you swap out the spacers until you get the right pop pressure. It's kind of tedious as you must disassemble and reassemble the injector for each test. But, 0.05mm of thickness corresponds to approximately 3 bar difference in pressure, so after the initial test of each injector you know approximately what amount of change you are looking for.

When I did it, I had eight junkyard injectors that I used for spare parts. I disassembled them, and then took some digital calipers and measured and sorted the spacers and springs by size. By using the 12 sets of spacers and springs (8 from the junkyard and 4 from my injectors) in different combinations, it was possible to bring my four injectors into spec.

In theory you can just order new spacers of the desired size, but you'd have to know what size you need first...

bgkast 11-14-2008 06:41 PM

1 Attachment(s)
OK, I just got my pop tester finished up and am having some trouble. I can barely get the pressure up to 2000 psi with ATF in the tester, and only about 1500 psi with D2 pumping as fast as I can. When I stop pumping the pressure falls to zero in less than a second.

Is the pressure supposed to fall this quickly? What could be the problem, an internal leak in the jack? I may try pulling it apart and using some thread-seal tape on the top threads of the jack cylinder. Maybe my $10 harbor freight jack is a POS.

Any other ideas or tips?

cornblatt 11-14-2008 07:48 PM

Quote:

Originally Posted by bgkast (Post 2021501)
OK, I just got my pop tester finished up and am having some trouble. I can barely get the pressure up to 2000 psi with ATF in the tester, and only about 1500 psi with D2 pumping as fast as I can. When I stop pumping the pressure falls to zero in less than a second.

Is the pressure supposed to fall this quickly? What could be the problem, an internal leak in the jack? I may try pulling it apart and using some thread-seal tape on the top threads of the jack cylinder. Maybe my $10 harbor freight jack is a POS.

Any other ideas or tips?

Your tester looks nice!

With the injector screwed on tightly, the pressure should hold without the need to keep pumping the handle. Mine will slowly drop due to leakage, maybe a few bar (less than 100psi) per second.

I assume you can't see any fluid leaking anywhere, so it must be an internal leak inside the jack. I used a low-grade chinese-made sub-$10 jack (actually two - I ruined one during construction :o) and they both had no trouble holding the pressure once everything was sealed. So, the jack should be able to do the job. Check that the pinhole at the top of the cylinder is still sealed (on my first attempt at building the tester, I only JB-welded one side of the pinhole and the JB-weld popped free and caused a problem similar to what you describe). Also, definitely use teflon thread seal tape where the jack nut attaches to the cylinder. It sounds like you are on the right track...

Graminal95 11-14-2008 09:34 PM

I can only tell you that my pop test that looks just like yours looses virtually no pressure unless it goes out the injector. I did use a 15 dollar jack and it did not have the hole in the top of the tube to be fill with JB weld. Also you should use something like ultra gray silicone instead of teflon tape on all oil/fuel fittings as the tape can break off and get stuck in the sintered metal injector filter, or the small oil holes of the engine....ask how I know!

I also put a rolled up coffee filter in the center tube, where the piston used to be to catch any small particles that might clog the sintered metal injector filter.

bgkast 11-14-2008 09:47 PM

Thread tape did the trick. Thanks!

whunter 03-10-2009 11:08 AM

Links for some commercial units
 
http://www.ntxtools.com/fuelsystem/otc4200.htm

http://www.rocken-tech.com/Injector_Tester.html

http://www.thompsondiesel.com/diesel%20test%20equip.htm

http://www.google.com/products?rls=com.microsoft:en-us&oe=UTF-8&q=diesel+injector+pop+tester&um=1&ie=UTF-8&ei=IYW2SbLzE5iyMbam9dUK&sa=X&oi=product_result_group&resnum=4&ct=title

Ebay search words: injection tester
http://motors.shop.ebay.com/items/injection-tester_W0QQ_newuZ1QQ_sopZ1?_rdc=1

Ebay search words: diesel injector tester
http://shop.ebay.com/items/diesel%20injector%20tester?_dmd=1&_sop=12

whunter 03-10-2009 11:25 AM

Other related links
 
Another home made unit.
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/159605551/m/6111024582

Which pressure gauge for a pop tester?
http://www.peachparts.com/shopforum/diesel-discussion/162026-pressure-gauge-pop-tester.html#post1251083

Injection pump bench test?
http://www.peachparts.com/shopforum/diesel-discussion/193585-injection-pump-bench-test.html#post1558635

what to clean out injector chambers?
http://www.peachparts.com/shopforum/diesel-discussion/167142-what-clean-out-injector-chambers.html#post1300759

Finally got the injector tester set up!
http://www.peachparts.com/shopforum/diesel-discussion/87248-finally-got-injector-tester-set-up.html

A fantastic DIY link. :D
HOW-TO: Rebuild Diesel IDI Injectors
http://vincewaldon.com/index.php?option=com_content&task=view&id=20&Itemid=28

vitop 04-27-2009 08:38 PM

how did it work?
 
After calibrating so closely, how did the car run?

cornblatt 04-27-2009 08:45 PM

Quote:

Originally Posted by vitop (Post 2186106)
After calibrating so closely, how did the car run?

The four injectors were within 4.5 bar before adjustment, and within 1.5 bar after. There was no perceptible change in how the car ran after adjusting them this closely (they were reasonably well matched to begin with).

rkpatt 04-28-2009 07:24 AM

Somewhere I saw a list of part # s from Mcmaster.com . Could someone who has it , please add it to this thread . - Thanks

whunter 04-28-2009 02:21 PM

Answer
 
Quote:

Originally Posted by rkpatt (Post 2186497)
Somewhere I saw a list of part # s from Mcmaster.com . Could someone who has it , please add it to this thread . - Thanks

Easy homemade pop tester
http://www.peachparts.com/shopforum/general-information/251436-easy-homemade-pop-tester.html

svendb 03-03-2010 09:46 PM

Great tester,thinking of buying one($450.00) Will now make my own thankyou.

Archangel 06-12-2010 12:21 PM

The real issue that you solved with the Teflon tape on the pipe threads was the O ring between the top of the pipe where it contacts the Jack nut.
The piston shaft keeps the O ring in place between the pipe and jack nut, and removing that shaft allows the seal to fall inward (assuming you even reinstalled the O ring as one of the two jacks I purchased for this project did not even have one).

In the original write up I don't even remember him even mentioning the part of the project where the pressure needs to be contained between the internal pipe and top jack nut.

I just cut a 1 inch piece of the hollow piston shaft and just JB welded that piece into the main pipe with a bit of it sticking out just high enough to help retain the O ring when JB welding the pin hole.

I'm willing to bet that one guy that had it fail so soon had the O ring slip out, (or inward) and stopped sealing the gap.

Other than that important issue, nice write up.

My first one will be all Purple with Yellow barrel/pump and all Red with a Yellow barrel and top nut (the only colors of powdercoat I had left).

I will also be adding the Teflon tape to tighten things up and as added pressure security.


Quote:

Originally Posted by bgkast (Post 2021501)
OK, I just got my pop tester finished up and am having some trouble. I can barely get the pressure up to 2000 psi with ATF in the tester, and only about 1500 psi with D2 pumping as fast as I can. When I stop pumping the pressure falls to zero in less than a second.

Is the pressure supposed to fall this quickly? What could be the problem, an internal leak in the jack? I may try pulling it apart and using some thread-seal tape on the top threads of the jack cylinder. Maybe my $10 harbor freight jack is a POS.

Any other ideas or tips?


Archangel 06-18-2010 09:25 PM

WARNING!! BE CAREFUL!!!!!!
 
Well, let's see.

The welding on the top nut did not go so well.
External Leaks!
RE-WELD!
External Leaks!
RE-WELD!
External Leaks!
Try brazing instead!

No external leaks at all, that is until it got to about 1800 psi, then POP the top blew off where the brazing was with a huge cloud of diesel fuel that sprayed everywhere!

There were no injuries but I did need to change clothes and take a shower!

But before it blew the top off, there were massive internal leaks that the pipe tape would not fix no matter how much I applied, and I even got some of that thicker tape that slowed it down some and the pressure would rise but it would not hold at all.
Looking at the design, those top threads were never meant to hold pressure, but the seal on the piston was.
Also my idea of a seal up top did not hold pressure either.

Also where the top nut contacts the barrel, there are no provisions in the original design to seal it.
If the fluid level in the external reservoir is higher than the top of the barrel, the air will vent through the tiny gap and the fluid will rise and then overflow leaking out, hence the original fill plug mounted only 1/2 way up the tube!
I solved this leakage issue with a tiny diameter "O" ring between the two.

Other than that one guy with the internal pressure leakage issue, I can't believe nobody else has mentioned, or had any of the other issues.

I'm going to duplicate the piston out of brass with a hole through it to the top for the fluid to pass through going directly to a "T" fitting that threads into it.

I will also have the original seal mounted lower in the tube than the pin hole so that it and the top nut threads will not have to hold any hydraulic pressure.

It will be just like the original bottle jack design only the piston will not move, and instead of the screw on top there will be a pipe thread fitting.

There will also be a Plexiglas spray shield between me and the unit at all times!


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