View Full Version : Changing Crank Position Sensor

black V8
05-18-2016, 10:39 PM
Like the title says I need nfo on changing the crank sensor. I've done a search and found lots of threads referencing it but nothing so far that explains it. Anyone got a link or can point me in the right direction. Thanks in advance, Tom.

05-18-2016, 11:03 PM
Which year SC? Early differs a bit from late, as an example.

I have a '90 Sc, and the last time I did mine the hardest part was getting past the plastic shield. The nut is dealt with depending on the assortment of tools at your disposal and the size of your hands. The harness routing needs a bit of attention as well as being careful to not abuse the connectors. I set the gap by eye, not that there was a lot of play to worry about. Overall, I don't recall it being a complex procedure once I had the correct replacement.

What are the symptoms that make you think your's needs replacement?

black V8
05-18-2016, 11:20 PM
It's my 90 5spd, while driving it stumbled and died, upshift light came on. Got it started about a half hour later and got it the couple of miles home where it died again not to start again. Balancer bolt is still in but a I haven't had a chance to have someone else crank it while I see if it wobbles. Car has 180 000 kms, I replaced the cam sensor a few months back when it started randomly bucking. That sorted that out.

Cheers Tom

05-19-2016, 12:32 AM
Checked for codes?

sam jones
05-19-2016, 03:43 AM
Good evening

If the crank sensor is bad I would check:
- The harmonic balancer rubber elastomer for cracks/missing material.
- The accessory belt forward and aft edges for fraying. This is one possible sign that the balancer is about to fail.

To remove the sensor.

Jack front of car and secure with jack stands. Disconnect the accessory belt and move it to the side for more access. Remove plastic balancer shield (10 mm nut at 12 o'clock position if installed). Disconnect both crank sensor electrical connectors to the DIS harness. The tools necessary for sensor bolts (2) removal (if they have not be modified) are 5.5 Metric or 7/32 SAE open or box wrench. [email protected] sell a set named "midget wrenches". Rotate engine crankshaft so the harmonic balancer vane is not between the sensor. Remove sensor. I remove the sensor and bracket as a assembly. The bracket has two bolts and one nut/stud. All 8 mm. The tools I use are:

- 10 mm socket 3/8 drive, ratchet, 5-6" extension to remove the oil coolant line attached to the oil pan at the 6 o'clock position for more access.
- 5-6" 6 point thin wall box end wrench for the nut/stud due to jackshaft assembly.
- 1/4" drive ratchet, 10 or 12" 1/4'' extension and 1/4" universal drive.
- 1/4" 8 mm 6 point shallow socket.

Carefully remove sensor from top or bottom.

Installation is reverse of the above.

As KTM stated carefully route the crank sensor harness to avoid damage from the rotating supercharger belt. After sensor is installed do the following:

-Turn engine/balancer so that vane is between the two half (or gap) of the sensor.
- Have excellent lighting. Don't guess or assume at this point or engine no start will result.
-Leave sensor bolts snug enough to adjust air gap. You can use a business card or match book cover for above and below clearance. If the card or match book cover can be "slide" comfortably between the sensor and vane without interference the gap is good. Tighten bolts when satisfied.
-Start engine. If you hear rapid tapping sound. Sound down engine. Readjust air gap. Restart engine. Check for engine MIL. Road test car.

Hopes this helps.

Good Luck.

black V8
05-19-2016, 09:45 AM
Thanks guys for the responses. I'll get at it next week when I'm back in Ontario. I appreciate the help.

Cheers Tom