The compression test is basically the same for each engine type, but a diesel engine has a higher compression ratio so should be a higher pressure therefore a higher pressure gauge is required, and different adapters are needed to fit in the injector holes or heater plugs if fitted.
Petrol / TVO engines
Testing a petrol or TVO engine is fairly simple as the testing is done via the spark plugs, or rather through the spark plug holes, to be more precise. An adapter is screwed in place of each spark plug in turn and then the pressure gauge is connected to the adapter. In the tractor world, it is most likely to be either 14mm or 18 mmsized plugs.
As you are testing each cylinder, the
