#1 cyl at TDC. Valves closed. Cam pulley 180deg off... HOW?! Lombardini LDW 903 Dsl

[777funk]

I don't understand this. The crank pulley is at TDC and the keyway is in. I can feel it's a compression stroke, the valves are shut, and the engine runs (low on power, exhaust smells a little raw). However, the timing marks on the cam pulley are 180 degrees off. How can the valves be closed?

[777funk]

Picture

[jt11791]

I think the marks are supposed to line up at TDC before the intake stroke. If you you're on the compression stroke and the valves are closed, then all is right. Remember, it take two rotations of the crank to complete one cycle. The cam turns at half the crank speed, so after one more rotation, the marks will line up.

[777funk]

I'm fairly sure that the compression stroke (not exhaust) is what counts for timing marks.

FWIW, the injectors are cam driven (and timed). So thinking about it, the engine can run with the cam 180 out.

[skipperpete]

Which cylinder are you calling # 1[emoji780]flywheel end or timing belt end. The valves and Pistons might get a just a bit too close to each other with the camshaft out by 180°.

[777funk]

Flywheel side is what the manual calls 1. Also, i have the cam in the compression stroke. The valves are both fully shut. The pulley however is 180 from the proper tick mark as can be seen in the picture.
.

[Rumpi]

There should be a mark on the crankshaft pulley (white point under a tooth) that you have to align with a mark on the oil pump cover. That marks the OT for cylinder 1. In that position the camshaft pulley mark should align.
Your picture is not focused on the crankshaft pulley but I can barely see the mark on the oilpump cover (recessed point about 12 o'clock) and the tooth under it has no mark, so you are not at OT. The tooth above the keyway could have a mark (no focus) as could other teeth.
If you have the workshop manual (free download) it is explained there.

[777funk]

Yes. This is what's being used to determine TDC on cyl 1. There are marks on the acc belt crank pulley and timing belt cover as well as marks on the crank timing belt pulley and the oil pump housing. Both show the engine to be on the mark. I can also feel the compression and weight of the TDC position while turning the engine by hand with a strap wrench.

Also, here's what I have used as a reference during this check.

[Wotname]

Originally Posted by 777funk

Flywheel side is what the manual calls 1. Also, i have the cam in the compression stroke. The valves are both fully shut. The pulley however is 180 from the proper tick mark as can be seen in the picture.
.

I don't know if this helps or not however the manual calls for the valve timing to be carried out at #1 TDC exhaust stroke.

[777funk]

If this is the case, i don't need to worry any further about being 180 out on the cam. Where can I find this bit of info?

[Wotname]

Originally Posted by 777funk

If this is the case, i don't need to worry any further about being 180 out on the cam. Where can I find this bit of info?

Page 37

[777funk]

I wonder why it doesn't specify compression or exhaust on the timing belt instructions on the pages previous. This seems to be a vast oversight.

I do think you're right. However, this goes against how most other engines are timed (usually marks matched on compression stroke).

[Wotname]

^^ well it is Italian

I thought it was strange how it says to first find TDC compression and then rotate crankshaft 360 degrees to TDC exhaust before continuing with the valve timing

[Rumpi]

This is an interference motor. The valves won't hit if they are 1 tooth out but that's all. In the posted photo cylinder 1 is not on TDC.

[Mike Banks]

Your camshaft turns at half engine speed--so if it is 180 degrees out, you need to take off the timing chain, rotate the engine to the next TDC and put the timing chain back. It will now be correctly timed.