Diesel engine compression test
The pressure is checked in the same way as described for a gasoline engine.
The following differences must be kept in mind: The temperature of the oil must not exceed 30º.
Transporter T4 compression tester must be specifically designed for diesel engines.
Since the pressure in a diesel engine is much higher, the compression gauge for gasoline engines may fail. ♦ Disconnect the electrical wire from the fuel shut-off valve “STOP” at the injection pump and insulate its end.
♦ After unscrewing the union nuts, remove the high pressure fuel pipes and protect their holes from dirt.
♦ Unscrew the nozzles and remove the heat insulating washers.
♦ Put a heat-insulating washer on the compression gauge adapter and screw it into the injector hole of the first cylinder (Fig. 196).
Rice. 196 Compression test with a special pressure gauge from VW
♦ Have an assistant press the gas pedal all the way down and start the starter.
♦ Turn the crankshaft with the starter until the pressure gauge shows the highest pressure.
♦ Check all cylinders one by one in the same way. The lowest pressure must be at least 80% of the highest. Low and uneven compression pressure can be caused by worn piston rings, but in this case there must be a large oil consumption. Compression should not be lower than 26.0 atm. (2.6 MPa).
Volkswagen T4 engine . Main technical characteristics of the Transporter .