Leakdown and Compression Interpretation needed...

[Peter]

If possible, I am trying to determine the internal condition of my engine...I bought a leakdown tester mainly for a couple of gas powered vehicles I have..thought I would try it on my '86 jetta TD on one cylinder only and useing 100-psi going thru the glow plug hole gave me a 6% loss and held steady there with no problem... I know that 6% loss for a gas motor would be very good to excellent, but concerning a diesel, would this number be to high.. also when useing a compression tester on that same cyl..with 5 revolutions I am showing 380psi and with ten revs 450+psi... the vehicle is original with over 500k/kilo and needs heat to start when the temps drop to -15C

[Peter]

For compression testing, you keep rotating the engine until the maximum pressure is reached and the needle no longer moves.  I'd feel fine about 6% leak down provided it's going through the rings.  With 450 psi compression it should not need any assistance to start down to single digits °F provided glow plugs, timing, and cranking speed are all up to snuff.

..probably weak starter, still the orginal, and checked one glow directly hooked up to the battery,..completely dead..thanks

[Peter]

I was always under the impression that much more pressure is needed  when checking a diesel (more then 100psi)..difficult finding anything thru google..same say 200psi is needed...but when useing 50 or 100psi the percentages come up the same...a little hard to determine where the 6% loss could be..I really couldn't hear any noise, but then again this afternoon my area was a little on the loud side.... found my 80's subaru with 19% leakage and definitely enough leakage to hear it come up the dip stick..