[Tally_XJ]

If you have a Jeep with the 4.0 litre engine, then you have a crankshaft position sensor located on the upper left edge of the transmission bellhousing.

If you do not have a transfer case drop, and even if you do, this is one hell of a hard place to reach with your hand or tools. A transfer case drop will move the bellhousing down and away from the body just a little. Its enough though to make it a lot easier.

Its not a matter of IF the crank position sensor goes bad, but rather when the sensor WILL go bad.

If you have my luck, it will quit on you at a traffic light in 5 o'clock traffic or maybe worse, several miles into the woods on a trail.

Symptoms of a Bad Crank Position Sensor
- Engine will crank over when turning the key, but will not fire and run
- Engine may intermittently run bad, especially at idle
- Engine will just shut off as if you turned the key off and is hard to get it started again


A new sensor can be purchased at NAPA, CarQuest, or at Advance Discount Parts. It is also available from your Jeep dealership at not much more cost than from the aftermarket (or so I read). Since they are not that expensive, it is adviseable to always have a spare on hand for those moments when you really want to take your Jeep home with you.


What to do now to make it easier on you later

Purchase a new sensor. Either make the modification now and replace the sensor, or keep it in your Jeep for future use when your current sensor goes bad.

This time, when you change the sensor, it will be a little difficult, but making the following modification will make it much much easier next time.

Installation and tools

Installation is straightforward, but is a tight reach. The sensor is located at about the 11 o'clock position on the left upper edge of the bellhousing. If you look at the firewall just behind the valve cover and follow down to the bellhousing edge, you should see a black plastic thing there that is held in with two bolts. A wire lead comes up and into a weatherproof plug just in between the throttle body and valve cover. This is the sensor and its pigtail lead. On some models, Chrysler made a modification to the wire lead. It did not go into a plug end, but rather ran into and through the firewall directly to the ECU.

The special shouldered bolts that hold this sensor go in from the back side, not from above. Reaching them is the hard part of this process.
I have done this two ways. The first time, I got them loose using a 7/16" combination box end wrench from the top (hardest way). The next time, I used a 1/4" drive ratchet, very long extension, universal swivel (wobble) and a 7/16" or 11mm socket and went underneath the Jeep reaching up between the unibody tub and transmission. If you look up along the left side of the transmission where the shifter cable runs into the body tub, you should see the sensor there just behind the exhaust manifold. Using the ratchet and extension tools, unscrew the sensors two mounting bolts.
Take caution! DO NOT allow the bolts to fall into the hole where the sensor goes into the bellhousing! You might have to remove the transmission to get them out!

Once you have the bolts out, go back up into the engine bay and unplug the sensor lead and pull it out.

Now, go back under and put the bolts back into the holes and turn them in a few turns, but not tight just yet.

New Sensor modification
Looking at the photo below, it will show the modification you will need to make to the sensor mounting tab. I used a dremel type die grinder with a thin cutting wheel on it to cut the slots into the tab. A hand file might work but would take longer.



Use caution when doing this. You only need to open up the mount hole just enough to slip over the shoulder bolt. Dont make it deeper as the sensor could very possibly go too deep and contact the flywheel. This would instantly destroy your new sensor.

What you are doing here is making the sensor installation easier by preventing the necessity of completely removing the mounting bolts. After this mod, it will allow you to simply loosen the bolts a little, slide the sensor out from the top, and then install a new (modified spare) sensor and tighten the bolts. You wont lose the bolts, you wont drop them into the bellhousing, and you should be able to use an open end wrench from the top to loosen them.

NOTE: Keep a few zip ties handy so you can tie the wire lead back away from the exhaust manifold. The manifold can and will melt the wires if they touch and you will be replacing or repairing the sensor again!

[jeeperanthony]

good idea

[yellowxj]

SWEET!!!!!

[Radon]

Had crankshaft sensor problems in my Ford Ranger. Had to replace the sensor 3 times and yes it was a b1tch. But that does seem like a good idea i will have to do that if i ever have to replace that sensor on my XJ

[Radon]

[cher_88]

mine was real easy.........i did it when i had the motor out . but great idea