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Old 10-09-2016
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Which TDC Mark To Use

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I have the heads off the engine and I thought I would actually see if the crank shaft positioning sensor put #1 at TDC _ well it doesn't.

With everything out of the way, there is an additional timing mark on the front of the timing chain cover.

The green arrow is pointing to it, I had to shine the light behind it to get a decent photo, so you're actually looking at the shadow of the new found timing mark.
The red arrow is pointing to the small protrusion indicating that this is the actual mark for TDC and not the crank shaft position sensor.

I can confirm this easily with the heads off as I can tell that #1 is at TDC.
If I move the harmonic dampener to the CPS position as TDC, I can clearly see that the piston is no longer at TDC, it's about 15 degrees out from TDC.

The question is, which TDC mark to use when timing the cam shaft synchronizer and sensor ?

Everyone is using the CPS as TDC, but as I discovered, it's not actually TDC.

What's the Ford dealership using ?

Here's a better photo, the protrusion on the end of the timing mark can be seen too.

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Last edited by Jeff R 1; 10-10-2016 at 12:13 AM.
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Old 10-10-2016
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The timing mark(s) on the damper/pulley will show TDC using a mark on the timing chain/belt cover.
Depending on the engine there could just be 1 line on the pulley and then 0deg and BTDC/ATDC degs on the cover marker...or 0deg and BTDC/ATDC degs on the pulley and just 1 line on the cover.

But these marks have nothing to do with Crank position(CKP) sensor.
The CKP sensor reads a Tone Wheel, 1 tooth every 10deg, minus 1 tooth for a gap, so 35 teeth.
The gap represents TDC, but because it is an electronic interface the gap doesn't need to be at the CKP sensor when the visual pulley lines match up.
Tone wheel Gap could be at CKP sensor at 10deg ATDC or BTDC doesn't matter as long as it is the same each time.
Ignition system is just programmed for that, its electronic not mechanical like a distributor.
So CKP sensor can be placed where ever it fits, lol, as long as ignition system is programmed for that location.

CPS is the same.

The pulley marks are a visual reference for us, as are cam and crank gear marks

Instructions are available for each engine model, for CPS alignment, that is what Ford dealer would use

Last edited by RonD; 10-10-2016 at 12:00 PM.
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Old 10-10-2016
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Join Date: Jul 2016
Location: BC Canada
Posts: 1,234
I don't think I understand what you're saying. I'm not so worried about the CKP sensor, but which timing mark to use when positioning the synchronizer in relation to the CKP sensor.

With that said, don't we need a point of reference to initially set things up ?
I'll use the timing mark on the timing chain cover and reset the synchronizer with the tool according to that TDC mark.

The difference is very little on the tooth position of the synchronizer any way between the timing marks.
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