PeachParts Mercedes-Benz Forum - View Single Post - How do you run a compression test on a diesel?

stevebfl · #6 03-13-2004, 02:42 PM

1. Test through glow plug holes or through the injectors holes? Benefits of either?

It doesn't matter as long as the adapter is designed for the application. I used to go through the glow hole (20 years ago). My first attempt to do it through the injector hole was to get a nozzle holder and remove the nozzle and weld a fitting on the chamber. I found that I got terrible readings. The reason was I had significantly changed the combustion chamber size by leaving the whole nozzle holder empty. The device that screws in the nozzle holder hole for compression readings lets no volume inside.

2 What about the injector lines. Should these not be removed ( if testing thru the glow plugs) to prevent the injector from affecting the pressure reading. And from the engine to prevent it from starting in a warm climate?

See answer to #3

3. How do you prevent the injector pump from spraying fluid everywhere ( if the lines are removed)?

For all the automatic vacuum controlled systems, just pull a vacuum on the fuel shut-off diaphram.

4. The pressure readings are of course subjective.

Of course!