308 QV Crankshaft Position Sensor replacement

Was unable to find a step by step guide for changing crank position sensor‘s so I thought my experience might be of help to someone in the future.
My 308 is a 1985 Euro QV model but the Process should be the same (or very close) for all QV models 83–85.

Changing all (3) crank position sensor‘s took me around 8 hrs. total because of my leisurely pace, couple coffee breaks and lunch. The job wasn’t hard at all, and with anything Ferrari don’t get in a hurry.

 

Tools required for the job.
1/4” ratchet
1/4” x 3”extension
1/4” deep 8mm socket

3/8” ratchet
3/8” swivel
3/8” x 6” extension

3/8” sockets - 10 mm, 13mm, 17mm
Phillips screwdriver
Regular screwdriver
Very small regular screwdriver

adjustable mirror
Pen style magnet
Floor jack, two jackstands, lug nut wrench.
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You’ll need to remove the left rear wheel (Driver side) and inside fender skirt.
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Loosen the lug nuts on the left rear wheel (just a little bit). And place jackstands under frame at rear of vehicle. You’ll need to have the vehicle raised at least 10”-12” off the ground at the front of the rear wheel opening so to be able to access the crank sensor located at the 7 o’clock position.

 

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Once the vehicle is secured on the jackstands, left rear tire and fender skirt is removed.
Remove the side scoop ducting that runs from the scoop to the oil cooler. It’s held in place by 1 - 10mm bolt/washer and set pieces aside.
Locate the crank position sensor at 3 o’clock position.
NOTE- All (3) crank position sensor‘s are held in place by two 8mm nut/washers.
Remove the 2 - 8 mm nuts and remove the washers with the pen magnet. You may half to rock the position sensor from side to side to loosen the washers.
The sensor can now be lifted up and off the threaded studs.
The electrical connector for the position crank sensors is secured in place by a metal spring clip. Turn the connector over till you see the end of the spring clip and then gently pry the end of the clip outward so you can get your fingers under the clip and gently pull it out of its seat and then set it aside. The connector can now Image Unavailable, Please Login be disconnected and position crank sensor unit removed.

 

Use this old crank position sensor and check it against the (3) New crank sensors to ensure the connector is the same and make sure the holes for the mounting studs are the same distance apart.
My new crank position sensor‘s had mounting holes that were farther apart so I needed to mount each one in the vice and using an air Dremel tool oblong the mounting holes.(this can also be completed with a small round hand file) Then place each one on the mounting studs of the original sensor at 3 o’clock position to check that the mounting holes are Image Unavailable, Please Login close enough for the new sensor to slide over the studs and set flat in position.

Now you should have all (3) New sensors test fit and ready to proceed. Take note how wiring for sensors or routed to connectors.

 

Accessing the crank position sensor at 11 o’clock position.

to access this sensor I found it easiest to first remove the front bank distributor cap and let it lay against the cam cover and firewall. I then disconnected the (3) vapor hoses that attached to the oil breather.
#1 - hose that connects to the top of the oil breather and runs under the Plenum to the airbox.
#2 - connects to the oil breather and cam cover crossover pipe.
#3 - is the small vapor line that connects to the left rear corner of them Plenum. Image Unavailable, Please Login Image Unavailable, Please Login
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Remove the 13 mm bolt holding the wiring clamp and lastly, remove the 17 mm bolt holding the oil breather to the bell housing. Now the oil breather can be lowered out of the way and you are able to access the 11 o’clock sensor located under the distributor and behind the aluminum water pipe housing Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

Finally the last crank position sensor located at the 7 o’clock position is pretty self-explanatory, and needs to be accessed from underneath.

reassembly - be sure to connect oil breather vapor lines to their respective places before mounting the oil breather once again to the bell housing. Makes it Sooo much easier.

couple of tips. - I found that when trying to reinstall the 8mm nuts to the studs that if I place a small scrap of paper towel over the end of the socket and then press the 8mm nut into that scrap pushing nut and paper towel into the end of the socket held nut from falling out until positioned and threaded over stud. I tiny drop of super glue on the washer placed over the nut held it in place until it was positioned in threaded also. That’s about it!

 

• Oh and one last word of caution.
• DO NOT OVERTIGHTEN 8mm nuts. They are just holding that tiny sensor in place. Snap off one of those mounting studs and your week just got very ugly LOL Image Unavailable, Please Login

 

Mike good morning and thanks. Pretty safe to say I won’t be a novelist. No, haven’t started the car yet as it’s 28° with a cold north wind. Supposed to jump back up to the 38° range in the next day or two.

 

Been chasing a slight miss for quite some time..
Here’s the original crank sensors Image Unavailable, Please Login


One last comment. If you need to oblong the holes on the new sensors, make sure that you clean any metal shavings off the sensor For installing.

 

Noticed that the last couple months when I would start my car it would run poorly and then just quit. Twice had to push it back into the garage. Decided it was time to change them out. Also found a damaged vapor line that I hadn’t noticed before.

 

I see you also posted in the “technical section”. Very good idea.
Steve Magnuson and the guys will get you fixed up.