Injector Leak-Off Test

aptionstyle = |headerstyle = background:#ccf; |labelstyle = background:#ddf; |datasty----

Overview Guide
Ford Model:	Mondeo_Mk3
Petrol/Diesel:	Diesel
Estimated Cost:	?
Difficulty?	Easy/Medium
How long does this take?	?

The Test Kit

To perform a leak-off test you will need a set of measuring bottles, some lengths of tubing 3.2mm inside diameter, a set of leak-off connectors and four plugs with 7 mm entry holes.

I used four hair colouring bottles that are very cheap on eBay. Likewise the 3.2 mm tubing is also an eBay purchase are were the second hand leak-off connectors. The four plugs can be made simply by drilling with a 7 mm drill into any hard material. This could be hard wood, plastic or in my case metal.

The Ford leak-off pipes are not quite as they appear. The black rubber outer conceals a hard plastic inner tube which is why the pipes are so rigid. I didn't think that I could pull the car's leak-off pipes off the connectors so I bought a scrap set and cut the pipes off these and then removed the outer rubber covering. You can see the inner hard plastic tube inside my clear plastic tubing in the photo below.

Unplug the car's leak-off connectors and push your plugs onto each one. If you don't plug these pipes then air will be drawn into the high pressure injection pump which will cause problems with running the engine for the test.

Then plug your connectors onto the injectors.

The hair colouring bottles come with tapered nozzles that you can cut the end off and push the clear plastic tubing onto them. It helps to mount the bottles on a metal strip just so that you don't get mixed up with the results.

The Test

The test that I used starts with 2 minutes running at idle followed by:

30 seconds with the accelerator held at 3000 rpm followed by:

30 seconds at idle followed by:

30 seconds with the accelerator held at 3000 rpm followed by:

30 seconds at idle followed by:

30 seconds with the accelerator held at 3000 rpm followed by:

30 seconds at idle.

The Result

Good injectors should not leak more than 25ml in this test. Looking at my results from left to right the first one is an original factory fitted injector in this car and shows a good 20ml result. The second is an injector recently reconditioned by Swadincote Diesel and just passes the 25ml test. The next two show fail results of 30ml and 28ml respectively.