Critical to diesel engines is the fuel injector pop pressure. Diesel injectors open at a specified pressure and spay fuel into the cylinder. For a 1993- 1998 VW TDI, the bentley's manual states this pressuer is 190 - 200 Bar for a new injector and 170 Bar is the wear limit.  For a Mercedes 617  Engine found in 300D and 240D and 300SD the pressure is ??/

I built this pop tester for testing Mercedes injectors from a picture i found on the www.mercedesshop.com forum.  It is made from a grease gun, a mercedes fuel injection line, some fittings and a pressure gauge. I used a good 30.00 liquid filled pressure gauge from the local industrial rubber and gasket shop.  I cut the injection line how i wanted it then went to the friendly local Hillsboro Hardware store with all the pieces and put it together. A compression fitting attaches the injector line to the whole thing.  I got all the hardware at hillsboro hardware nad the grease gun and gauge at Industrial Rubber and Gasket in Nashville. I got the injector line at pull a part.  I hope it fits VW injectors otherwise I'll have to get another injector line.