Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-12-2013, 02:53 AM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,482
Electronic Pop Tester Cheap

I collected parts over the last year and finally got around to putting together my pop tester. I started with info from these links:
How to build a diesel injector pop tester
DIY Pop Tester
Replace injector nozzles, set pop pressure, big improvement! - Topic

The hydraulic setup is from a kit to test a pressure relief valve in Ford Rotunda Diesel engines, sold to dealers, and same as the 3rd link above. I bought on ebay ($120 I recall), much less than the original >$500 price. The pump looks similar to an Australian model that sells for ~$450.

The fittings and pressure gage are from McMaster-Carr. From my notes:
1 5269K311 Metric fitting, 1/8" NPT-M to 6mm tube ($4.11)
2 50925K197 Steel T fitting, 1/4" NPT, MxFxF ($6.38)
1 50925K341 Steel bushing, 1/4" NPT-M to 1/8"NPT-F ($1.60)
1 50925K133 Steel fitting, 1/4" NPT-M to 3/8"NPT-M ($2.00)
1 4000K713 Gauge, Dual, 3.5" dial, 1/4"NPT-M bottom, 3000 psi range
The 6 mm fitting above is the trick, to fit the M-B fuel tube. Other people have fabricated their own, not knowing it exists if you know the PN (now you do). Use high-pressure steel fittings everywhere, not brass, and check the pressure ratings.

The pressure sensor is a GE Druck 0-3600 psig, w/ 1-5 VDC output. I got it cheap on ebay ($22 I recall) and power with a 9 VDC AC adapter. For data acquisition, I use a Dataq DL-149U ($15 ebay), which has a USB interface to a notebook PC. I used the free software, which limits to 250 Sps speed. I sprayed into a yogurt cup with a stainless strainer from 99 Cent store.

I first tested 5 injectors from my 1985 300D engine which failed 3 yrs ago at 330K miles (#1 piston beat up, others missing chunks). I bought the car at 278K miles and the prior owner had it from new and regularly took it to the dealer (at high cost), but I didn't see where the injectors had been replaced (need to review the thick file). I wondered about bad injectors, but all popped uniformly at 1900 psi on the gage. The electronic trace shows them oscillating between 1900-2000 psi, so the peaks might be too quick to catch on the gage.

I added a 0.1 mm (4 mil) shim to each, which brought each to 2000-2100 psi oscillations. Another source stated 0.1 mm = 100 psi increase, on average. A few increased ~150 psi. 4 had a factory washer of 56 to 60 mil, but one had 35 mil though still popped at the same pressure. I am guessing it was a dealer replacement. All had "Bosch" on the housings and internal nozzles. The sound and spray pattern looked just like this video (not mine):
pop-testing - YouTube

I put these 5 into the replacement 1981 engine now in my 1985 300D. They made no noticeable change in the engine. It idles smooth, but the air cleaner vibrates (like most). I then tested the 5 injectors from the 1981 engine. I bought it cheap on craigslist, so don't know the history, but it looks new on the top end and compression was 400-410 psi in all cylinders (tested with injectors out). They all popped at the same 1900-2000 psi oscillation and fine spray cone. I haven't opened to clean or shim yet. I will later test the injectors in my 1984 300D.

Finally, I read many posts with questions about buying shims, with high prices for small kits, or people buying punches to make their own. It seems I am the first to competently search McMaster-Carr because I got them for ~$4/bag of 50. I got ~4 sizes, but only used the 0.1 mm ones. They even have "Made in Germany" on the bags. Store this info:
PN 98055A105, Metric Spring Steel Shim - DIN 988, 0.1 mm th, 6 mmID, 12 mmOD, pack of 50. I also bought a bag of PN A106, A107, & A108 (0.2, 0.3, 0.5 mm).

I know this helps undercut high-priced sellers, but I enjoy helping cheap bastards like myself. I considered keeping my secrets and offering pop testing to others, but I am a well-paid aerospace engineer and don't want to fool with fussy customers, so pop your own injectors. If I lose my job, I may grovel for testing work. As for the instrumentation, that was simple for me since I once did academic experiments in liquid sprays.

One problem I ran into was that the pump started relieving ~1000 psi on the 5th injector, with nothing leaking out anywhere. Same deal when I tried an earlier injector, so assumed it was inside the pump. I took it apart and found 2 screw-in spring relief valves from the head back to the reservoir, one stamped "1000 psi" and the other "3500 psi". Before that, I had taken out the 2 ball check valves and inspected, but no change. The pump piston has two bores, so it must be 2-stage - a big piston (1000 psi) to move volume then the small piston comes into play for the high pressure (3500 psi). Anyway, I didn't find root cause, I just unscrewed the 1000 psi relief valve and inserted a 1/8 NPT plug there. I only had a brass plug, so hope it doesn't yield, though it would just go into the reservoir. The pump worked fine after that change. The diesel injectors serve as relief valves anyway, so if I only use for pop testing the pump should be safe.
Attached Thumbnails
Electronic Pop Tester Cheap-sam_0280.jpg   Electronic Pop Tester Cheap-pop-test.jpg  
Reply With Quote
  #2  
Old 11-12-2013, 03:42 AM
Stretch's Avatar
...like a shield of steel
 
Join Date: Sep 2009
Location: Somewhere in the Netherlands
Posts: 14,396
Quote:
Originally Posted by BillGrissom View Post
...
I know this helps undercut high-priced sellers, but I enjoy helping cheap bastards like myself. I considered keeping my secrets and offering pop testing to others, but I am a well-paid aerospace engineer and don't want to fool with fussy customers, so pop your own injectors. If I lose my job, I may grovel for testing work. As for the instrumentation, that was simple for me since I once did academic experiments in liquid sprays.
...
Tell me more!

(And thanks for the elcheapo information)
__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
Reply With Quote
  #3  
Old 11-12-2013, 09:49 AM
mach4's Avatar
Registered User
 
Join Date: Jul 2011
Location: San Diego County, CA
Posts: 2,736
I'm impressed. Very nice setup and execution.

Thanks for the write up
__________________
Current Stable
  • 380SL (diesel)
  • Corvette C5
  • Manx
  • Baja Bug
  • F350 Powerstroke
  • Auburn Boattail Speedster replica
Reply With Quote
  #4  
Old 11-12-2013, 10:36 AM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,482
Quote:
Originally Posted by Stretch View Post
Tell me more!
..
Dataq has probably the most affordable A/D products. They even offered a free board that plugged to a serial port in the 1990's. I got one and used for one son's middle school science project (put a strain gage on a scooter).

My spray research developed a laser droplet sizer for rocket injectors. The closest commercial product is the "Phase Doppler Particle Analyzer (PDPA)", which I think is still sold today. My coaxial beam design was much simpler and reported the same distributions. It was so elegant that the PDPA designer stepped forward at the conference and said he had the same idea (didn't pursue?). I never got Air Force funding to continue. Probably the fact the AF lead was a close friend of the PDPA developer and expressed open hostility played a role (your tax dollars at work). If really interested, look thru issues of ILASS and ICLASS symposiums. After I left academia, industrial interest grew in liquid spray analysis as companies developed common-rail diesel and gasoline direct-injection systems, which have proven very effective.
Reply With Quote
  #5  
Old 11-12-2013, 10:48 AM
gastropodus's Avatar
Mercedes Benz apprentice
 
Join Date: May 2010
Location: Portland, OR
Posts: 430
I used to work with John Bowers, the founder of Dataq. He is a great guy, and I'm sure he would be pleased to know that Dataq products are useful in this application!

Kurt
__________________
- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).
Reply With Quote
  #6  
Old 11-12-2013, 03:08 PM
Registered User
 
Join Date: Sep 2006
Location: san marcos, Texas
Posts: 428
:bowdown:
__________________
1982 300sd from craigslist $800 greased on one tank with NO CONVERSION in the Hot Texas Sun. (currently dead & awaiting engine damage investigation and/or longblock swap)
new daily: '03 vw 5speed jetta tdi wagon. bagged&chipped
Reply With Quote
  #7  
Old 11-12-2013, 03:32 PM
Stretch's Avatar
...like a shield of steel
 
Join Date: Sep 2009
Location: Somewhere in the Netherlands
Posts: 14,396
Quote:
Originally Posted by BillGrissom View Post
Dataq has probably the most affordable A/D products. They even offered a free board that plugged to a serial port in the 1990's. I got one and used for one son's middle school science project (put a strain gage on a scooter).

My spray research developed a laser droplet sizer for rocket injectors. The closest commercial product is the "Phase Doppler Particle Analyzer (PDPA)", which I think is still sold today. My coaxial beam design was much simpler and reported the same distributions. It was so elegant that the PDPA designer stepped forward at the conference and said he had the same idea (didn't pursue?). I never got Air Force funding to continue. Probably the fact the AF lead was a close friend of the PDPA developer and expressed open hostility played a role (your tax dollars at work). If really interested, look thru issues of ILASS and ICLASS symposiums. After I left academia, industrial interest grew in liquid spray analysis as companies developed common-rail diesel and gasoline direct-injection systems, which have proven very effective.
If I still had access to a University library I would - I'll start off with a search for PDPA - thanks
__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
Reply With Quote
  #8  
Old 11-12-2013, 05:20 PM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,482
So people don't get too enamoured with electronic recording, I don't think it added much to what I could see on the $14 gage from McMaster-Carr, and wouldn't change what shims I decided to add. I am just used to collecting data electronically and reviewing at my leisure, rather than trying to read a gage. Indeed, I would trust the gage first since too many ways to mess up the reading from an electronic one.

One place it might help is if performing pop testing for customers. It seems more comforting to provide plots rather than just a few numbers written by hand, maybe more assurance that the injectors really were pop tested. Of course, one can always fake time traces too, so best would be a short video of each injector test. Indeed, I think some type of video measurement would be the best enhancement to quantify the spray quality. I tried this quickly using a little borescope camera I have ($18 ebay), but couldn't get good images. Next pass, I might try back-lighting with a strobe light, which worked well when I tested similar sprays at an Air Force lab.
Reply With Quote
  #9  
Old 04-27-2014, 02:46 AM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,482
I found another possible source for cheap and common injector shims. I was fixing the AC compressor on a car today and needed to a shim washer to set the air gap on the clutch plates. I grabbed my bag of McMaster-Carr shims and found they fit perfectly in the clutch drive. Thus, one might go the other way - use AC clutch shim washers in a M-B injector. These clutch shims should be fairly common. I don't know the increments, but most air gaps spec 15 - 30 mils, so they likely come in 5 mil increments or 0.13 mm, which increases pop pressure ~130 psi.

Another thing I'll add is recent experience with my 1984 300D. I found that 3 of the 5 injectors popped ~1600 psig (instead of 1950 psig), which means they were non-turbo injectors. I installed a set of 5 from my old 1985 turbo engine that failed, after testing that they all popped 1900-2000 psig. I haven't noticed a difference in idle or driving. I thus surmise that pop pressure is probably not extremely important. I think it is more important that each injector has a good spray pattern, with no dribbling or streamers. As far as cyl-cyl balance, I expect the volume delivered by each injection pump piston is the most critical element.
Reply With Quote
  #10  
Old 04-27-2014, 08:56 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,274
Hmm.
I was under the impression that pop pressure affects the timing of the spray, and too low a pressure, can alter the cylinder's individual timing... of course, if your chain is loose... having light pop pressure could solve the issue...
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #11  
Old 04-27-2014, 11:42 AM
Registered User
 
Join Date: Jun 2009
Location: S. Ontario Canuck
Posts: 165
thought the injectors for n/a vs turbo were diff in some way, i'm also not clear on the engine here
Quote:
I put these 5 into the replacement 1981 engine now in my 1985 300D
Reply With Quote
  #12  
Old 08-01-2014, 11:30 AM
funola's Avatar
Registered User
 
Join Date: May 2005
Location: NYC
Posts: 8,134
BillGrissom,

The p/n 5269K311 Metric fitting, 1/8" NPT-M to 6mm tube does not come up searching McMaster. Can you check?

How useful is the electronic pressure gauge vs the analog gauge in setting pop pressure? Which one do you use and why?

Thanks!
__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked
Reply With Quote
  #13  
Old 09-01-2014, 06:12 PM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,482
Strange. I replied to post #12 long ago, but now don't see the response. Anyway, I checked McMaster's site and still see PN 5269K311 at same price. I even posted the screenshot (not going to repeat).

In answer to other questions, all three 300D engines I have are turbo-diesel (917.952? I forget M-B PN's). I have no idea how the 1984 engine wound up with 3 non-turbo injectors (before I bought it). Not in there now.

I use both the analog gage and the electronic recording. Without a "peak capture" needle, it is hard to catch the exact "pop pressure", and if not damped, some of the needle bouncing could be from momentum rather than true pressure fluctuations. My gage has neither I recall. Last pass, I didn't use the Dataq recording because their software keeps hanging up, making usage very tedious, and I was rushed. I'll try to find a better A/D product or write my own custom software.
Reply With Quote
  #14  
Old 04-18-2015, 08:13 PM
TnBob's Avatar
Registered User
 
Join Date: Dec 2009
Location: Shelbyville, Tn
Posts: 1,907
For Tube
OD Pipe
Size Each

6 mm 1/8 5269K311 $4.11

Product Detail
Steel Compression Tube Fitting, Straight Adapter for 6mm Tube OD x 1/8 NPT Male
Each
In stock
__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."
Reply With Quote
  #15  
Old 04-19-2015, 03:52 PM
KarTek's Avatar
<- Ryuko of Kill La Kill
 
Join Date: Jun 2007
Location: Bahama/Eno Twp, NC
Posts: 3,249
Quote:
Originally Posted by BillGrissom View Post

My spray research developed a laser droplet sizer for rocket injectors. The closest commercial product is the "Phase Doppler Particle Analyzer (PDPA)", which I think is still sold today. My coaxial beam design was much simpler and reported the same distributions. It was so elegant that the PDPA designer stepped forward at the conference and said he had the same idea (didn't pursue?). I never got Air Force funding to continue. Probably the fact the AF lead was a close friend of the PDPA developer and expressed open hostility played a role (your tax dollars at work). If really interested, look thru issues of ILASS and ICLASS symposiums. After I left academia, industrial interest grew in liquid spray analysis as companies developed common-rail diesel and gasoline direct-injection systems, which have proven very effective.
Quote:
Originally Posted by pgringo View Post
:bowdown:
Yeah, no friggin' kidding!

I'd love to adapt the pressure sensor to my injection pump test rig to act as a timing tester. I envision the pressure sensor driving a trigger circuit that flashes a LED which is pointed at the timing wheel.

This would let me see the exact time the injection pulse peaked and adjust individual cylinder timing accordingly.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 12:10 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page