Editing Crank Angle Sensor (section)

==The Crank Angle Sensor==

With the rotor and CAS cover off, you can see the chopper disc and photodiode assembly on the left.  The chopper disc has six holes (one square for home) one for each cylinder, then 360(?) slits for measuring to the nearest 2 degrees.  It seems incredible overkill.  There's not much you can do here except say "oooh, aaaah".  Tune in next week, same bat time, same bat channel.

[[image:Cas_6.jpg]]

And then a miracle occurs.  Here is the bearing that lives inside the distributor.  After 17 years it was completely dry and rooted.  Here is also the bearing number for the replacement.  Even if your CAS is perfectly fine, your distributor may be making horrible noises because of this bearing.  My horrible noises were particularly noticeable at 1500rpm, and with the bonnet up it was easy to hear it was coming from the distributor.  If the bearing gets bad enough it can destroy itself, and fragments of it can end up in your CAS chopper disc, so it's a good idea to change this as preventative maintenance.  You probably need a press to get this bearing out, you could hammer it with a punch, but it's not very elegant.  I got the auto sparky who sold me the CAS to change the bearing too, as I had no press.

[[image:Cas_7.jpg]]

Here is the old CAS assembly.  The old chopper disc gets used again.  Basically you undo the big screw holding the shaft on, and get the chopper disc out of the way, then this all lifts out, and Bob's your uncle.  It's all potted in epoxy, fairly solid construction.  I was thinking about dissecting it for educational purposes, but I decided to keep it in the car as a dodgy backup.  You can also see the ACA part number.  The sparky who sold it to me said they're good (he would), and it's got a two year warranty, so we'll see (touch wood).

[[image:Cas_8.jpg]]

If you look in the slit under sunlight, you can see the little windows inside for the LED/photodiodes.  I tried and pretty much failed to take a photo.  On the left rear there's three slits that read the outer fine slots in the chopper disc, and on the right front there's one hole that reads the inner six cylinder marking slots.

[[image:Cas_9.jpg]]