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  #1  
Old January 21st, 2018, 18:06
Chaindog Chaindog is offline
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Accessing CPS/CKPS

So I've been busting my knuckles all weekend trying to get at my Crankshaft Position Sensor, which is dying but not yet dead. I just can't get anything on the bolt. I've seen a few videos of people replacing them, but they always seem to be on rwd models, so they have a lot more room under there.

So what tips do people have for changing this darn thing? I've got about 18" of extensions and a universal joint on it. Any ideas?

(Side note: I saw a bunch of posts on other forums about an access panel under the dash. After tearing most of my dash apart, I found out that a lot of people call their grand cherokee just "cherokee." So that panel does not exist on mine. )

Max
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  #2  
Old January 21st, 2018, 19:56
JeepNoob JeepNoob is offline
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Re: Accessing CPS/CKPS

The interwebz (this place included) will tell you that the best way to change the CKP is to place the vehicle securely on jack stands, throw every 3/8" extension you own, plus 8 different wobbly joints, a 12mm wobbly socket, and of course a 3/8" drive flex-head ratchet under the Jeep. And then get your double-jointed, 80 lb Filipino buddy to actually change the thing out...

Me, I found the best way to change it is to remove the whole air intake system, box included. (It's only a couple clips and three 13mm fasteners on an HO model, hardly difficult.) This gives you enough room to sneak under the intake manifold with a crow's foot (If you don't know what that is, Google a "crow's foot wrench.") on a short extension. Actually seeing or feeling the bolts can still be a bit tricky, but after trying to remove it from the rear, I've found this method works best. Even taking my sweet, sweet time, I've done this job multiple times, using this method, in about an hour. Just my $0.02.

Last edited by JeepNoob; January 21st, 2018 at 20:04.
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  #3  
Old January 21st, 2018, 21:30
Chaindog Chaindog is offline
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Re: Accessing CPS/CKPS

Haha you described the instructions that I've seen perfectly! As many extensions as possible and small hands/flexibility.

I hadn't heard of a crows foot wrench, but they look pretty sweet! I'll pickup a set tomorrow and let you know how it goes. Thanks for the tip!
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  #4  
Old January 21st, 2018, 22:15
JeepNoob JeepNoob is offline
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Re: Accessing CPS/CKPS

No problem. Just have fun finding a decent set of crow's feet these days. I picked a Sears/Craftsman metric set up a couple years ago for $40 or $50 for this exact job. They work good, but good luck walking into a Sears these days and picking up a set...

And DO be careful with them!!! I can't stress this enough. If it doesn't feel like it's the right size for the bolt or the angle-of-the-dangle between the crow's foot and the exstension and/or the ratchet isn't quite right, JUST. STOP. Keep in mind, these things are basically like the open end of a wrench. It's better than a crescent wrench, but guys in the know (like moi) call crescent wrenches "nut-f***ers" for a reason. And an open-end wrench is just a step above that...

You WILL cause yourself more trouble and WILL cost yourself more $$$ by rounding off those bolts then you will by taking your time and making sure you have a good bite on the bolts before going full wrench-gorilla on them. So, if the set-up smells like s***, looks like s***, and/or feels like s***, it's probably s***. Take a step back, have a mental cigarette (or an actual cigarette), re-evaluate the situation and go from there.
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  #5  
Old January 21st, 2018, 23:03
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Re: Accessing CPS/CKPS

Quote:
Originally Posted by Chaindog View Post
So I've been busting my knuckles all weekend trying to get at my Crankshaft Position Sensor, which is dying but not yet dead. I just can't get anything on the bolt. I've seen a few videos of people replacing them, but they always seem to be on rwd models, so they have a lot more room under there.

So what tips do people have for changing this darn thing? I've got about 18" of extensions and a universal joint on it. Any ideas?

(Side note: I saw a bunch of posts on other forums about an access panel under the dash. After tearing most of my dash apart, I found out that a lot of people call their grand cherokee just "cherokee." So that panel does not exist on mine. )

Max

18" isn't enough. You need something closer to 36". I had to have enough extensions to get all the way past the crossmember in order to make it work. And I was using one universal and one wobble extension. The bolt head is probably 11mm.
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Old January 22nd, 2018, 04:48
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Tim_MN Tim_MN is offline
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Re: Accessing CPS/CKPS

More extensions are better, working from the far side of the cross member is what I prefer. Have a helper guide the socket onto the bolt. If you have Gorilla hands/arms, unbolting the front driveshaft from the T-Case makes more room.

Remove the top bolt first, install the bottom bolt first, you don't want to drop a bolt into the transmission.
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  #7  
Old January 22nd, 2018, 06:09
Jeff/Alaska Jeff/Alaska is offline
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Re: Accessing CPS/CKPS

Tim is on track here. Just have a buddy run the wrench from above while you direct the socket onto the bolt head from below. A headlamp is good thing. If worried about dropping a bolt use a magnetic socket insert.
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  #8  
Old January 22nd, 2018, 09:44
ID96XJ ID96XJ is offline
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Re: Accessing CPS/CKPS

I don't understand why everyone uses a bunch of extentions from under vehicle.
I just reach in from above with a wrench or a 1/4" drive ratchet with no extention and 11mm or 7/16 socket.

Mine is a 96 4x4 auto.

Last edited by ID96XJ; January 22nd, 2018 at 09:49.
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  #9  
Old January 22nd, 2018, 18:05
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Re: Accessing CPS/CKPS

Quote:
Originally Posted by ID96XJ View Post
I don't understand why everyone uses a bunch of extentions from under vehicle.
I just reach in from above with a wrench or a 1/4" drive ratchet with no extention and 11mm or 7/16 socket.
It depends on the year and build.
In my 2001, with the twin mini-cats and an advance evaporative system, the CPS is totally invisible from behind or from the engine bay.
Unbolting the crossmember and lowering the transmission helps bring the CPS into sight, after moving a bunch of wires and hoses out of the way.

My engine is out right now and before the new stroker goes in, a fresh Mopar CPS will be installed. I don't ever want to do this again on the road.
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  #10  
Old January 22nd, 2018, 18:59
lawsoncl lawsoncl is offline
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Re: Accessing CPS/CKPS

Quote:
Originally Posted by JeepNoob View Post
guys in the know (like moi) call crescent wrenches "nut-f***ers" for a reason. And an open-end wrench is just a step above that...
Ah yes. That colorful expression reminds me of one of my favorite YouTubers. https://www.youtube.com/user/arduinoversusevil


+2 on using a magnetic socket or electrical tape so you don't lose the bolt in the bellhousing.
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  #11  
Old January 22nd, 2018, 19:28
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Anak Anak is offline
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Re: Accessing CPS/CKPS

Quote:
Originally Posted by ID96XJ View Post
I don't understand why everyone uses a bunch of extentions from under vehicle.
I just reach in from above with a wrench or a 1/4" drive ratchet with no extention and 11mm or 7/16 socket.

Mine is a 96 4x4 auto.
I have tried that. My hands don't fit.
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  #12  
Old January 23rd, 2018, 03:20
JeepNoob JeepNoob is offline
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Re: Accessing CPS/CKPS

Quote:
Originally Posted by lawsoncl View Post
Ah yes. That colorful expression reminds me of one of my favorite YouTubers. https://www.youtube.com/user/arduinoversusevil


+2 on using a magnetic socket or electrical tape so you don't lose the bolt in the bellhousing.
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Uncle Bumble**** is one of my favorite boob-toobers as well. An old shop "foreman" of mine turned me onto that channel and I've learned a few tricks from it. Sometimes I wish the format was more relevant for me though. Not everybody has a two-car garage with a Bridgeport milling machine...
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  #13  
Old January 24th, 2018, 10:50
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Re: Accessing CPS/CKPS

I've been changing them for over 20 years. I drop the crossmember and let the whole rear crop a couple of inches. That coupled with a long extension from the rear works cleanly. It is no more than 30 minutes by myself.
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  #14  
Old January 24th, 2018, 17:26
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Re: Accessing CPS/CKPS

Long extensions and thin arms has worked for me. It's tight, but do-a ble. If my arms were a little fatter, I would have to drop the front driveshaft for easier access.
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  #15  
Old January 24th, 2018, 20:51
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Re: Accessing CPS/CKPS

There seems to be several different techniques for this. On my 89, I had to remove the front driveshaft to gain access, but on my 'new' 96 the CPS came out using only long extensions and a universal joint on the socket. I did use a 1/4 inch drive though. The smaller drive gives more clearance than does the usual 3/8.
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