I need to get a leak down test to see if my engine is still good but not on my 5.9 it's a 4 Cylinder OHC engine but I can't find a mechanic shop in my local area willing to do it or they don't do them at all. I did a compression test and all 4 cylinders read 140 PSI. I actually did it last year and then a few months ago and it was still the same. So is there a need to do a leak down test since the compression is good? Doesn't that mean it isn't losing any compression through the valves?