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Discussion Starter · #22 ·
i haven't forgotten about this, but i've just been occupied with repairs on another 09 vw eos 2.0t tsi to get it back on the road.

i gave up on trying to work the 90 degree mirror attachment and just ziptied the camera lense to the usb cable so i could get a look at the valves from the piston upwards.

video1.mp4
video2.mp4
video3.mp4

my eye is untrained, but it seems like the same valve is hanging down no matter where in the stroke the piston is. is this a broken valve? it also seems like it's leaving a mark on the top of the piston as seen in the first video i uploaded in a previous post.
 

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I think the compression problem was caused by a broken valve spring, or the retaining collet.
If that is the only problem, no need to remove the head, just remove the camshaft, and providing the valve stem is not damaged,
replace the damaged part/s.

If there are metal fragments stuck in the top of the piston or the valve is damaged in any way, the head would have to come off.
What looks like metal fragments in the video, might be specs of carbon or oil, and distorted by the camera view.

For a better look, solder 2 wires to a small 12V white light LED, insulate between the wires and cover connection with heat shrink tubing.
Connect the wires to 12V and put the light through plug hole into cylinder, and look down the plug hole.
 

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Tom is right, but that’s a big “if“ that the valve or stem is not damaged - it looks to be hanging down pretty far, and if the “half-moon kiss” on the piston is real, damage is pretty much a given.

You’ll have to pull the camshaft as a first step anyway. If all the valves close and seal (you’ll be using something like this to put air in the cylinder), just make a sacrifice to the deity or stars of your choice and vow to never sin again. You have been blessed.

If the valve is damaged, indicated by the air whooshing past it, you’re part way to pulling the head and replacing the valve.

Before doing any of that, though, get some borescope shots of the cylinder walls with the piston down. No point in doing any work if the walls are damaged.
 

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Tom is right, but that’s a big “if“ that the valve or stem is not damaged - it looks to be hanging down pretty far, and if the “half-moon kiss” on the piston is real, damage is pretty much a given.

You’ll have to pull the camshaft as a first step anyway. If all the valves close and seal (you’ll be using something like this to put air in the cylinder), just make a sacrifice to the deity or stars of your choice and vow to never sin again. You have been blessed.

If the valve is damaged, indicated by the air whooshing past it, you’re part way to pulling the head and replacing the valve.

Before doing any of that, though, get some borescope shots of the cylinder walls with the piston down. No point in doing any work if the walls are damaged.
If it is a broken valve spring or collet, the valve would be totally free to move up with the piston, and thus it would be unlikely to bend.
Usually when valves bend or break, it is because of incorrect timing. The valve is being pushed down as the piston is coming up.
 

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Discussion Starter · #26 ·
i feel stupid. the 90 degree endoscope attachment isn't an actual mirror, but just a piece of reflective foil and just like all other glossy plastic electronics there was a piece of protective film over the mirror.

in any case, i finally got a good look at the cylinder walls and other than 1 anomaly all i could see were machining marks. the anomaly is so uniform in shape that i don't think it's the result of any damage.

video1.mp4
video2.mp4
video3.mp4

so what is the next step? how do i confirm what is actually wrong with the valve? i mean at a minimum i know i need to remove the valve cover, but i gotta tell you i've seen images of the 1.8t awm engine with the valve cover removed and i can't make out anything that looks like a valve stem, let alone a spring of any kind. my only previous experience with upper engine work is a 289 v8 in a 66 mustang so i'm a bit out of my element.
 

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The valves are not in the same plane as the piston, they are offset by several degrees (as I'm sure some people know). Would they still move up and down freely since they would have to slide across the piston surface as they move?

Standwebber; once the valve cover and camshaft are removed, the lifters have to be pulled. Under them, you will see the valve springs and hopefully a stem.
 

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PZ I am aware that the valves move at an angle to the piston travel, but I do believe that a free floating valve would move up with the piston during cranking,
and it would fall very little between piston cycles. Once the engine is rotating there would be very little movement of the valve.
I don't know for sure what the problem is, but my theory is plausible.

stanwebber Remove the camshaft and cam follower, and inspect the valve stem, collet and spring.
NOTE: The cam bearing caps MUST go back in the original positions and orientation.
 
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