After our broken alternator belt overheating adventure last Saturday, I have gotten the engine out, the heads off, and everything visually inspected. Bob H. gave a couple lessons on Differential Leakdown Testing (101 for the mechanically inept such as I) and how to use it to determine if one has leaking valves or pistons.
The tester that I'd like to use is backordered at Harbor Freight so I'm doing what I can with the tools on hand. I don't know if I have acquired enough information to know much, but I'd like to post my procedure and results so smarter guys might make the good suggestions.
This morning I figured out how to snap the basic compression tester's hose onto my air compressor, so at least I had the means to pressurize the cylinders.
Before the engine was pulled, we did basic compression testing on cylinders #1, #2 and #4. #1 and #2 read in the low 90's after ten turns of the starter engine. #4 read 0. I didn't check #3, figuring that I had trouble right here in Carlsbad City.
Second, I pulled the valve covers and determined that #4's valves were too tight, which might be the cause of the leakage. But managed to break a pencil off in the plug hole feeling for TDC. So the engine was pulled.
After disassembly, foreign object removal, and inspection, I smeared some 30W oil around the cylinder walls on all four cylinders, re-installed the heads and torqued them, and adjusted the valves.
Prior to hooking the hose to each cylinder's plug hole, I shot a little air into the cylinder with a nozzle to (I hope) spread the oil around the cylinder a bit more.
Hose was hooked to each cylinder and the regulator on the compressor turned up from zero. On all four cylinders leakage could be heard starting at around 20 psi, and in all cases, it was into the case. Could be heard at the oil filler neck. I don't have any way to measure the volume of the leakage, but all four cylinders seem to be about the same
-- and leaked more as the pressure was turned up.
I'm not sure if this information is useful, or how to interpret it.
#1 and #2 did okay on the initial basic compression test, and #'s 3 and
4 seem to act about the same as those two on this crude leakage test...