KellsLaredo

Was changing out the CPS today on our 2005 Grand Cherokee Laredo with the 3.7 V6 and once I removed the harness connector and bolt, it was pretty clear that the sensor was really stuck in the bore at the bottom, passenger side, of the block. Sprayed some penetrating lube but had no luck freeing it up. Didn't take much effort to snap the top of the sensor off, so that the top of the remaining sensor body that's stuck in the bore is flush with the block (nothing left to grab on to)

It looks like the bore is exposed to the weather and water can penetrate down as far as the O-ring near the base of the sensor. Wonder if this is the reason it's so stuck?

I'm in deep here as the car won't run now, and welcome any and all suggestions on getting this out! Going to try again tomorrow (Sunday). If all else fails, can I drop the oil pan and somehow push it out from "inside" as it appears to be mounted just above the top edge of the oil pan. Or does it abut the crankshaft and isn't accessible?

Thanks in advance for any help, this has been one frustrating experience!

Gorillaxj

is the metal tab still on it? if it is try and get a flat blade on it and spin it a little. then get the blade between the block and the tab and twist the screw driver to pry it up a bit. should pop it out. if its not the idk without seeing a pic to get any "good" ideas...

KellsLaredo

Thanks for the reply. I did exactly that with the tab and the screwdriver, and the thing wouldn't budge. I think the torque from the tab actually cracked the sensor body at the tab, and eventually the top half came off where the metal tab joins the plastic body. So now the top half of the sensor and the tab are free and the rest is stuck in the bore.

I don't have a picture, but just think of it like you'd used a hacksaw to cut the sensor "in half" right at the block, so that the part that's still in the engine is even with the top of the bore (hole) that it slides into in the block. So in essence, I have nothing left to grab on to, and one really stuck (bottom half of the) sensor.

I did a search before attempting this and all had said it was pretty easy. Got me thinking maybe there's something else other than that one bolt holding it in? Seems that way from how tight it is, but I don't think there is. Just the friction from the O-ring?

Tomorrow my plan is to use a Dremel with a 1/8" bit and drill a hole right down the center of the remaining part of the sensor (if I can get the tool in there, it's really tight to the frame), screw in a flathead screw to give me something to grab onto, and hopefully somehow pry it free without pulling the screw out and leaving the sensor in. If that doesn't work, I'm not sure where to go from there... But I'm just winging it with that plan and open to any and all suggestions!

KellsLaredo

Well I took it on yesterday and have to say that it was really stuck! I picked up the flex extension for the Dremel tool as the tool itself was too long to fit between the sensor and the frame. I used a 1/8" bit to drill down the center, and I screwed in a hex head screw using a 1/8" drive. That worked very well and the screw was in there rock solid (didn't know this until I got it out and was always worried I was going to pull it out or break the rest of the sensor body)

Next came the prying with a small but beefy 14" flat bar and lots of spray lube for the O-ring. No luck getting it to move forward, but after a while I noticed it would move back in. Took a long time trying to get it free with the little movement it had, no joy at all. After a few hours at it and building frustration, I grabbed the larger pry bar and 5 lb sledge and had at it. Much to my surprise, after a number of decent hits (it wasn't giving up easily), it popped out in one piece! I thought I'd broken it again for sure the way it came out, but thankfully not.

Short story is that the design does indeed allow road contaminants to enter, and the bore was oxidized, leaving a "lip" that prevented the O-ring (and thus the sensor itself) from sliding out. This lip also prevented the insertion of the new sensor so I had to use the dremel to take it down as flush as I could without distorting the hole. Lots of that lovely brown rust dust was generated.

I have to say, I'm amazed more 3.7 owners who need to swap the CPS haven't run into this problem. All accounts on the internet have been trouble free from what I've read. Figured I'd post this detailed, just in case some other unlucky owner ends up going down the same road. Good to know it's not a dead end!

Gorillaxj

glad to see you got it. sounds like a PITA