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steveltx

Couldn't locate the crank position sensor for 99 Boxster

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Hi all,

I searched the net and found a few threads that describe the location of the crank position sensor, one of

the thread even had the picture to show. I was under the car for quite a while and still couldn't match the

picture with the car.

The thread says it's close to the flywheel housing. Where is flywheel housing?

Is it on the driver side or passenger side?

Is it close to the bottom of Air Oil Separator?

Thanks for your helps.

Steve

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Steve:

The flywheel housing is the part of the transmission case that extends forward (in the case of a Boxster) of the actual transmission and covers the flywheel, clutch and pressure plate, etc... As such, it's not on the left or right side of the car, but rather sits in the middle of the engine bay. At the forward end of the transmission (again, in a Boxster), the flywheel housing mates up to the rear of the engine and, around its circumference, you can see the heads of a number of bolts that hold it snug to the rear of the engine. It is below the bottom of the AOS.

Here is a photo of an engine removed from the car. To help orient you, the AOS is circled in red, the AOS bellows has a blue arrow, and the yellow arrow points to the crankshaft position sensor.

post-6627-0-76036900-1343495360_thumb.jp

Since the transmission is not mated up to this engine in this photo, you won't see the rear face of the engine. However, if you look for the bolt heads I mentioned earlier, you can locate the CPS in between two of those bolt heads. You can clearly see the threaded holes for those two bolt heads immediately above and below the CPS (click on the photo to enlarge). In your case, those two holes will have the bolts in them as the transmission is still bolted in place.

Regards, Maurice.

Edited by 1schoir

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Steve:

The flywheel housing is the part of the transmission case that extends forward (in the case of a Boxster) of the actual transmission and covers the flywheel, clutch and pressure plate, etc... As such, it's not on the left or right side of the car, but rather sits in the middle of the engine bay. At the forward end of the transmission (again, in a Boxster), the flywheel housing mates up to the rear of the engine and, around its circumference, you can see the heads of a number of bolts that hold it snug to the rear of the engine. It is below the bottom of the AOS.

Here is a photo of an engine removed from the car. To help orient you, the AOS is circled in red, the AOS bellows has a blue arrow, and the yellow arrow points to the crankshaft position sensor.

post-6627-0-76036900-1343495360_thumb.jp

Since the transmission is not mated up to this engine in this photo, you won't see the rear face of the engine. However, if you look for the bolt heads I mentioned earlier, you can locate the CPS in between two of those bolt heads. You can clearly see the threaded holes for those two bolt heads immediately above and below the CPS (click on the photo to enlarge). In your case, those two holes will have the bolts in them as the transmission is still bolted in place.

Regards, Maurice.

Hi Maurice,

Thanks for the detailed information. I know roughly where the sensor is now. I am still trying to find it because there

are just many pipes and steel bars in the area and I couldn't get a clear view.

I have been under the car for 2 days now and still trying. Access to the bolt of AOS was not too difficult from the bottom and I

used it as the reference point, I think it's not very far from the AOS mounting bolt?

I am a little bit frustrated. I am not handy to fix cars. Any suggestion is appreciated.

Thanks so much.

Steve

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Steve:

You are correct, it is not far from the LOWER of the TWO AOS mounting bolts.

If you put your finger on the lower of the two mounting bolts from the AOS, then go straight down about 4 inches, and about 1 or 2 inches towards the rear you will have your finger on the CPS. IIRC, the one bolt that holds the CPS in place is near the top of the CPS.

Here is another photo that should nail it down for you, although the engine and transmission are really dirty:

post-6627-0-05659900-1343622579_thumb.jp

To help orient you, the yellow arrow points to the LOWER bolt at the bottom of the AOS housing;

the green circle is surrounding where the inboard end of the psgr side half-shaft (axle) attaches to the output flange of the transaxle (the half-shaft has been removed in this photo);

the red arrow is pointing to the bolt head that would be in the threaded hole that is immediately above the yellow arrow in the PREVIOUS photo;

and the blue arrow points to the CPS. If you click on the photo, you might even be able to see the bolt that holds the CPS in place, although it is covered in dirt in this photo.

If you still are not able to see it, put your finger on the flat little square surface on the transmission flywheel housing to which the white arrow is pointing and then slide your finger to the right (i.e., towards the front), and your finger will be on the CPS.

Regards, Maurice.

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Steve:

You are correct, it is not far from the LOWER of the TWO AOS mounting bolts.

If you put your finger on the lower of the two mounting bolts from the AOS, then go straight down about 4 inches, and about 1 or 2 inches towards the rear you will have your finger on the CPS. IIRC, the one bolt that holds the CPS in place is near the top of the CPS.

Here is another photo that should nail it down for you, although the engine and transmission are really dirty:

post-6627-0-05659900-1343622579_thumb.jp

To help orient you, the yellow arrow points to the LOWER bolt at the bottom of the AOS housing;

the green circle is surrounding where the inboard end of the psgr side half-shaft (axle) attaches to the output flange of the transaxle (the half-shaft has been removed in this photo);

the red arrow is pointing to the bolt head that would be in the threaded hole that is immediately above the yellow arrow in the PREVIOUS photo;

and the blue arrow points to the CPS. If you click on the photo, you might even be able to see the bolt that holds the CPS in place, although it is covered in dirt in this photo.

If you still are not able to see it, put your finger on the flat little square surface on the transmission flywheel housing to which the white arrow is pointing and then slide your finger to the right (i.e., towards the front), and your finger will be on the CPS.

Regards, Maurice.

Hi,

Mine is Tiptronic transmission. Is the picture different from manual transmission?

There is not much room under the AOS mounting bolt.

Thanks.

Steve

post-6984-0-75410500-1343792400_thumb.jp

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Steve:

I don't have photos of the Tiptronic transmission housing, so I'm not familiar with the shape.

Although the housing of the Tiptronic transmission is shaped differently from that of the manual transmission housing, there are two points to keep in mind:

1. The bolt pattern is the same, so you can follow the location of the bolts in the photos above, and;

2. On the manual transmission Boxsters, the crankshaft position sensor is actually mounted on the engine case (i.e., NOT on the transmission housing), so it should be in the same location pointed out in the photos.

Maybe someone else can provide a photo of that area with a Tiptronic.

In the photo that you have provided, you can clearly see the lower of the two bolts to which I referred (and it looks like someone replaced the factory OEM hose clamp oat the base of the AOS bellows with a worm clamp). Take a look (or feel) below and very slightly to the rear of that AOS housing lower bolt.

Regards, Maurice.

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Steve:

I don't have photos of the Tiptronic transmission housing, so I'm not familiar with the shape.

Although the housing of the Tiptronic transmission is shaped differently from that of the manual transmission housing, there are two points to keep in mind:

1. The bolt pattern is the same, so you can follow the location of the bolts in the photos above, and;

2. On the manual transmission Boxsters, the crankshaft position sensor is actually mounted on the engine case (i.e., NOT on the transmission housing), so it should be in the same location pointed out in the photos.

Maybe someone else can provide a photo of that area with a Tiptronic.

In the photo that you have provided, you can clearly see the lower of the two bolts to which I referred (and it looks like someone replaced the factory OEM hose clamp oat the base of the AOS bellows with a worm clamp). Take a look (or feel) below and very slightly to the rear of that AOS housing lower bolt.

Regards, Maurice.

Hi Maurice,

I finally found the CPS. It's about 1 inch from the of AOS lower mounting bolt. I used my hand to slide down from the

bolt and finally touched the CPS. I couldn't see it but I knew that's the one because I could feel the shape.

The problem now is how to replace it. The location is very deep and the space is very tight. I couldn't even see the sensor.

I think I will need to use my hand to feel the bolt and remove it. This won't be easy.

May be I need to have the garage do it.

Thanks.

Steve

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Steve,

Look at post #91 here. I had to fabricate a really long extension in order to get to that 5 mm hex bolt. I did mine on the ground, but I think it's easier with the car on a lift. Very easy to strip the bolt. It's also held in place with threadlock. So clean it up first, take your time, and use a quality hex head socket. If you do strip it, the Grabit tool also pictured worked really well in getting the old bolt out.

Search for crank position sensor and you'll probably find other methods and pictures on how to remove it.

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