I took the belt off, rotated the engine until Cyl 1 was top dead center, checked the timing mark, and it was spot on—then I realized that it had nothing to do with the cam timing, only the crank orientation. I took the belt off and everything. Sigh.
I pulled the plug for Cylinder 1 and ran 3 compression tests while watching the spark plug. On a whim, I tested with the new plug the first time then the original working plugs the 2nd and 3rd times. I recorded it all. Unfortunately, the dial for the compression gauge has a glare on it for #2-3, but doing a 4-crank, by ear anyway, compression test, I got 140, 145, and 148 PSI. For the first two, I didn't touch the throttle like I should, which is why I did the 3rd, but since it was so similar, I didn't redo it anymore.
Click the video link:
Compression/spark plug tests 1-3 video
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<source src="https://i.imgur.com/SgryeRa.mp4" type="video/mp4">
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I threw the videos together and added captions, but I didn't take the time to align them and add a soundtrack. You can hear a little of the music I was listening to in the background. I don't want a bill from the RIAA.
The spark looks very similar across plugs and tests. The light in the tester is whitish at first, then reddish. That indicates to me that my coils aren't producing enough voltage. I have a spark gap tester arriving tomorrow; I'll see what it says. Since these coils were working correctly, even if they are weak, I don't think that's the reason it won't start at all or even turn over.
I'm leaning toward compression because I did a leak-down test before reinstalling the engine. It was abysmal. If I put air pressure in the spark plug hole with both valves closed and the cylinder at the top dead center position, then sprayed carb cleaner on TOP of the valves, the carb cleaner bubbled until it was gone after a short while. It did this in EVERY cylinder. Now, I'd never lapped valves before, much less taken apart an overhead cam head, and VANOS tore everything down and put it back together. Lapping valves doesn't seem hard, but clearly, I must have done something wrong because the best the leak-down ever got was 20%, and most cylinders retained 0%. Listening to the engine during the leak-down test, the air was clearly coming out of the valves, usually on the exhaust side, but some on the intake side--and some on both. I could hear no air sounds from the crankcase or oil dipstick.
__________________
Donald Foss
2003 E53 3.0i, 5L40e (for now)
- self-rebuilt engine, valves, SL oil pump
- ported heads, both sides
- N55 intake manifold, 70 lb injectors
- GTX 2860R-clone 60mm top-mounted turbo
- progressive slip diff
- under chassis cats
- extra sensors wired to Arduino
- 15" touch screen dash-mounted