mc_hotmail

Came up with this idea to verify the TDC mark on the vibration damper of a 2.7t V6 engine. You can buy a similar USB snake cam (aka endoscope or borescope) for about $20. The camera head of mine is slightly bigger than the Audi spark plug thread, which is perfect.

I used a 15 inch breaker bar and a 15/16" socket (my substitute for the 24mm socket) to move the crankshaft near the TDC marker. Then while watching the computer screen, crank back and forth the TDC marker.

Inserting the snake cam into the passenger side front cylinder (closest to the radiator) shows that the cylinder is at bottom dead center, further away from the spark plug.

As shown in the attached picture, inserting the snake cam into the passenger side back cylinder (closest to the firewall) shows the cylinder is at top dead center, closest to the spark plug.

How you name that cylinder is a matter of choice, but TDC for the entire engine refers to cylinder one at TDC. This means physically, David (DMW96A6) is correct about the location of cylinder one.

For a 4-stroke engine, there are 2 TDC per cylinder per firing cycle,
but most people refer to the ignition TDC instead of the exhaust TDC. That means ignition-wise, David's firing sequence is also correct.

Conclusion: the first post of this thread is correct.

mc_hotmail

Image for the previous post.

DaveInSaltLake

That little assumption is not correct for this motor.

You could have accomplished the same thing with a 3-cent piece of wire or a free pair of chopsticks from your favorite Chinese restaurant by sticking either of them through the same hole you deployed your camera into.

Anyone still questioning this should see my earlier post with all the links.

Legaumais

Hello,

http://img38.imageshack.us/img38/238...ocylindres.png

http://img295.imageshack.us/img295/4...escylindre.png

Prospeeder

Just so everyones clear. Timing belt TDC is with cylinder #3 not #1 like most engines. You responses seemed sort of confusing...