Performing a Compression Test

Now I'm going to ask Dan here, who sat in the driver's seat to turn the car on the starter motor and with the throttle wide open and the choke off this should be done on a hot engine, so the engine is under its normal running conditions. I'm also going to take a wire off the coil because I don't want the coil throwing sparks out while we're doing this to HT leads that aren't connected to anything. What we'll expect to see is this thing gradually building up to a final pressure, which is the reading we'll take. And we do this on each cylinder. So Danny would you like to take it away?

Okay, clear? Yep. Okay, thank you. Right, so the reading we have here is 150, 60, 70, 80 PSI 180 PSI for this size of engine is very good. The workshop manual will give you a reading that you should expect.

The tool, the main indication in the tool, in the instructions for the tool. What we do now, we can release the pressure using this button here. Okay, so that's ready, and that can be unscrewed now. And we basically work our way along do it to all the cylinders. We'd expect roughly the same reading on each one.

So you'd expect it whether within about 10% on each one. So probably no lower say than 160 or thereabouts if that one's 180. They should all be within the same general region.