hawkeye99

any DIY for crankshaft sensor replacement?

tonyb635

You might have better luck if you edit you title to say this. Otherwise some may not be interested in the 535... There are some 535 haters out there.

hawkeye99

not asking them

Amherst

The crankshaft sensor on my 07 525Xi failed last week. I found replacing this sensor quite a difficult task. I can not offer you a DIY but can provide a pointer or two from my experience. The bentley manual calls for removal of the aluminum frame plate below the engine to gain access to the engine from underneath. I tried this method and failed due to all the obstacles still present even after the plate was removed. I was barely able to lay two fingers on the sensor in a very contorted manner. Pretty much useless.The front differential of our X cars is the biggest obstacle.
Probably on the two wheel drive version, plate removal would have been sufficient for servicing the sensor.

I lowered the vehicle and decided to attempt from the top. I removed the top half of the air filter housing including the MAF. Then I removed the resonator between the the air housing and throttle body. This gave me enough room to wiggle my arm down between the strut tower and the intake manifold and put a couple of fingers on the sensor and mounting bolt which is located directly below and toward the rear of the starter on the engine block. I was unable to visually see the sensor and did the removal and installation strictly by feel. I left the electrical connector intact during removal.

I assume you have the N54 version so your intake is different than my normally aspirated N52. But if you remove all intake tubing leading up to the throttle body your situation should be similar. I also have an oil separation system and tubing attached to the lower portion of the intake manifold that you do not have. This was also an obstacle but I was able to worm my hand around it.

A couple of important ***notes*** here.
First: Once the sensor is removed there is a direct hole in your block into the crankcase that points downward at about a 45 degree angle.
***DO NOT*** drop anything into the bore hole or introduce contaminants. Prior to servicing I recommend at minimum the area around the sensor and intake manifold be thoroughly blown clean with compressed air. A pressure washing then air would be better.
Second: Remove the sensor bolt.Then take the bolt and any loose tools, wrenches, sockets, ect., from your work area and vehicle and put aside so they do not mistakenly wind up in that hole.
Third: Have your new sensor and o-ring ready, pre oil the o-ring. Carefully wiggle the old sensor loose, pull out and remove. Put a miniature flat head screwdriver under the connector tab and remove the electrical connector from the sensor. Immediately install the new sensor and o-ring onto the electrical connector. Wiggle the new unit back into the engine block bore hole with the sensor mounting bolt hole sitting in about the two o'clock position when facing the side of the engine block.
To install the mounting bolt use your 6" extension and socket. Put a small piece of paper towel over the face of the socket and push the bolt into the socket. Rip off any excess paper visible around the outside edge of the socket. This creates a retainer for the bolt. (it keeps the bolt from falling out while lowering and starting the thread). The bolt is mounted on an angle of approximately 45 degrees upward to the ground and perpendicular to the engine block using a very light torque. Snug plus 30 degrees is enough. Bentley calls for 8nm torque. I could find no way to get a torque wrench in this space.

hawkeye99

sounds like a project; thanks for the great tips

Amherst

You are welcome.
This job is tough, you can not see the sensor and can barely touch it. Once the socket is on the bolt there is no room for your hand and dropping the (non-magnetic) bolt is almost a certainty. May want to place paper towel in socket on removal of bolt also to keep it there. Spent more time trying to retrieve dropped bolt than it took for the replacement. The open bore hole is a real danger. Overall a PITA.
Happy Wrenching!

Booyaazaa

I don't know about haters. Maybe just individuals who don't like the FI life.