No, you can't use the gauge on the compressor. Separate guage is needed, the compressor gauge measures tank pressure. The tank has a much bigger volume capacity than the cylinder does, so your reading would not mean anything.

Timing the leakdown gives you an indication just how big the leak is. People well versed in the leakdown test (I am not one of those) can tell you what the likely culprit is by the timing and pressure values.

Changing piston rings is not that bad if you are mechanically inclined. You do need to remove the head and check for scoring on the cylinder sleeve, and if there is a ridge, you will have to ream it out, so you can getthe piston out. You will also need to remove the oil pan so you can access the rod cap bolts so that the piston and rod can be tapped out by using a 2x2 piece of lumber. Some engines you can remove the piston from the bottom, but you will have to reinstall through the top, because of the need for using a ring compressor.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D