Timing Mark Sender - Speed Sensor / Reference Sensor

[Coral Red Syd]

Hi all,
Did a search on Timing Mark Sender 911-606-108-00-OEM and found alot of info.
Ohm test reveals one of the sensors is bad.
How do you access the sensor on the transmission bellhousing - have not been under there to look and wanted to get some input before I went under from anyone that might have done this job before. Have Bentleys and 101 projects for reference. Thanks
Cheers
CRS

[KCinBR]

I can tell you about where it is on a 88 Carrera 3.2, because I have my engine out at this time.
It's located on top of the motor at the very back center of the block next to the engine tin. It sets directly over the flywheel and is held on by a single allen head bolt. You MIGHT be able to bet to it after removing the AFM and air box.

IN the pic below the red line points to the sensor on a 3.2 motor

[3.2 CAB]

If you get the rear of the car up on the larger type jack stands, you can slide under it from the rear and remove what you need to. The sensors are mounted at the top, at the flywheel end of the engine on the bell/crank housing. Also if one is bad, the other might as well be replaced at the same time. They are both the same sensor, just different location. Follow the info in the Bentley book and you should have no problems. Good luck!

[3.2 CAB]

Not sure of your year car or engine??? I have changed mine out, did not had to remove anything except the sensor holder.

[Bobboloo]

On 84-86' the senders are on the other side of the flywheel near where the tan glove is in the picture above.

[Bill in OKC]

Yikes, it is scary that I know the routine. Jack up the driver's side. Remove DS rear wheel. The two sensors are high and to the right on the bell housing. The sensors are held in by an allen screw ??mm. I used some aerokroil to loosen up the sensor barrels and after getting them to rotate, they slid up and out without too much trouble. You have to unscrew a small clamp that holds the wires to the fender well. The rascal part was getting the grommet loose in the firewall. It is oblong and the two sensor wires along with the cylinder head temp wire run through this grommet. You have to reach way up in there to get it out and there is not much room for leverage. I ended up using the flat end of a long crowbar *yikes* but I was very careful and was able to get the tip of the grommet out and then the rest I could do by hand. (Getting the grommet back in is not too hard - I sprayed it with armor-all to make it slippery). After you get the grommet out there are slits for the sensor wires to slide out from the grommet. The CHT wire is there permanently. Up on the engine side, You have to unplug the cables from the bracket !and remember which one goes to which one - they can get swapped! If you are only replacing one sensor then it is not a concern. There is another small clamp on the intake manifold that has to be undone to get the cable out. Take care with the clamp as it will ride along the remaining cables and end up behind the manifold where it is almost impossible to get a hold of. Once this is done, you can feed the cable down through the firewall and remove the bad sensor. Good luck!

[Coral Red Syd]

Thanks so much for the replies!
I should have mentioned that the car is an '84 targa 3.2 L stock engine.
So I'm keeping my fingers crossed that the sensors are on the right driver's side.
I'll order two of the sensors as advised... if one is bad the other is probably not far off.
Thanks and I'll keep everyone posted.
Cheers
CRS

[Coral Red Syd]

Yup the installation was pretty easy. Did not have to remove the sensor holders and thus did not have to re-gap them. Just slid the old sensors out of the holder and the new ones in. WOW what a difference in starting the car.
Side note it was the reference sensor that went bad. As it went bad I found that the car would only spark in key ignition position 2 on its way back from position 3. I also changed out the electrical portion of the starter switch for good measure and tested it. The old one was fine and checked out, but I replaced it with a new one just to be sure.
Cheers
CRS