A 2001 Chevrolet 2500HD with a 8.1 liter engine came in with the complaint that the engine would stall. Sometimes it would restart right away and sometimes it would not. I checked codes and found a code P0335 stored for a crank sensor fault. I did a basic inspection for anything obvious and found nothing loose or out of place. I did a little research and found that the crank sensors themselves have a fairly high failure rate so I decided to remove it for inspection. I also found out that they can be very difficult to remove. This one was no exception. There is a 10 mm headed bolt that secures the sensor to the rear of the engine. The sensor is located on the driver’s side on top of the rear of the engine just in front of the transmission bell housing. I read multiple warnings about having to remove the transmission if the sensor breaks off. The pictures I had taken of removing the sensor did not come out very well, so there are just a few of the new one going in. However to detail the removal procedure I used, I started by removing the 10 mm attaching bolt. Then I was able to rotate the sensor back and forth while pulling up on the sensor. I managed to get it up about an eighth of and inch this way and then I started spraying a little penetrating fluid on it. I let it soak in for about ten minutes and tried again. Now it was out about a quarter of an inch and now I could slide a curved pry bar under one edge and lifted it up with a smooth motion making sure to keep the center of the force in line with the center line of the sensor. I sprayed it again and waited again. The next time I was able to lift it a little higher. I sprayed it again and pushed it back in some to help distribute the the fluid. waited again and the next time it came what I thought was most of the way out. Same thing again, spray, push and wait. Finally after about five to six times of this procedure and various pry bars, I was able to remove the sensor.
The sensor on the left is the old one and if you look closely you should notice that there are two o-rings and the new one on the right has only one. It is the lower o-ring being stuck that makes this so difficult to remove. A little bit of clean lubricant on the new sensor o-ring and it went in without any problems.
By the way replacing the sensor did fix the P0335 code and stalling problem.
A great writeup. Helped me get started. The original style sensor with the plug at right angle to the cylinder head makes it hard to get even a flex head ratchet wrench in there. Plus the Allison transmission hard tubing lines prevent using a 1/4 ratchet. I finally used a 10 mm combination wrench with a long screwdriver holding the box end of the wrench on the 10 mm bolt. After backing it out several turns, then was able to use the flex head ratchet wrench. The replacement sensor with the plug turned 90 degrees and parallel to the back of the head makes it easier to put the 10 mm bolt back in and tighten it up. I still took me about 2 hours because I had to get out from under the truck 5 or 6 times to get various pry bars, long screwdrivers, and various wrenches.