Renault Master 2.5L poor running

Renault Master 2.5L diesel turbo 2004 extremely poor running.

I was asked to drop in to one of my more local garages, for a bit of help with this vehicle.  It was running very poorly, in fact it was clearly misfiring.

They really just wanted me to carry out a quick compression test, as I can do it quickly with the scope.

So that was what I did;  well, a relative compression test anyway.

As you can see, in the image below, I also used a cylinder reference by connecting a dummy injector to No.1 cylinder and by using a low current clamp to capture the triggering.

Relative compression with sync
Renault Master 2.5L Relative compression. BAD

As the image shows, cylinders 2 and 3 are low on compression.  As soon as I saw that, I thought; Head gasket! because the low readings were on the two adjacent cylinders.

After the cylinder head was removed, the fault became clear.

Head gasket blown between 2 cylinders
Head gasket blown between cylinders 2 and 3

This really shows the power of the scope.