My new diesel injector pop tester and 1st test - PeachParts Mercedes-Benz Forum

Mercedes Man · #1 12-28-2013, 06:32 PM

Hello,

I would like to show everyone the new diesel pop tester I built using the information I found on this website. The old bottle jack was bought from a garage sale for a dollar. It works nicely and was last used to move the engine in my 300SD so I could install new engine mounts. Now this jack is the basis for this project. There are many miscellaneous fittings that I had laying around/bought from the local True-Value Hardware store.

There are two critical parts in this construction. For me, the easiest part to make was the ¼” to fuel injector adapter. I managed to get a ¼” brass coupling (was an air fitting) and soldered it to a Mercedes fuel injector line using lead solder and a propane torch. The worst part to adapt was the jack nut to the ¼” tee. I had made two attempts to weld to the cast iron jack nut with 6013 rod. The welds leaked in both attempts even with JB Water Weld sealing the inside. On the third try, I eliminated any welding on any cast iron. I sealed the top of the jack with a heavy washer. In the middle of the washer I welded a ½” galvanized coupling. It also leaked, and I ended up welding it all over again but with 6011 rod. I think I should have used the 6011 rod in the first place, and it would have not leaked. The 6013 welds tend to have more porosity increasing the probability of leaks.

I built the fuel reservoir from an insulated cup which had thick plastic. I drilled a hole in the bottom of cup and screwed a ¼” brass fitting into the cup. The bottom of the cup is sealed with JB Water Welder to ¼” brass fitting. The plumbing is all ¼” copper and compression fittings. I soldered a brass valve to the filling hole in the jack’s oil filler hole. The jack’s reservoir is JB Water Welded down to the base of the jack.

In the pictures, you can see how the ½” coupling is adapted to a ¼” nipple and how the tee is connected and plugged at the top. All fittings are wrapped with yellow petroleum. Teflon tape. I plan on buying a 3 ½” 2000 PSI gauge (non-liquid filled) from eBay to complete project.

After many, many times, I finally got to pressure test an injector. From the junkyard, I had bought a set of 5 injectors which sat around the house for about 3 years. These injectors said they were remanufactured for Mercedes Benz. I clamped down the jack to the table, filled the cup with diesel, and pumped the jack. I bleed the air out of the system, and within about 3 pumps of the jack, the jack got really hard to pump. I had watched the videos on YouTube, and their jacks were very easy to pump. Probably anymore pumping of this jack would have been dangerous because I had to use two hands and lean into the lever. It was hard as a rock. I observed the injector dripped a little bit. Also noticed that the injector body was wet. I tried another junkyard injector, and I got the same problem.

Is it possible the injectors are seized up inside? Do injectors seize up after sitting for long periods of time? Did the diesel do that? I know that I am at a disadvantage because I do not have a pressure gauge, but judging by the amount of force I am using to pump the jack (probably 3000+ PSI?), I would bet it was beyond what the jack should be safely capable of handling.

Hope this helps people who are making their bottle jack pop testers.