Rubicon transfer case sensor

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kmac5130

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Oct 26, 2021
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Doylestown, Pennsylvania
I was trying to locate a leak of ATF on my transfer case and found that it seems to be dripping down from a sensor on the 241 transfer case. A gentle wiggle of the sensor showed some fresh red ATF around the edges, so I believe the O-ring has failed and needs to be replaced.

After searching for a while online, it seems like it is the transfer case speed sensor which has been discontinued. I can’t find it anywhere new, but externally it resembles part# 5149034AA which is a camshaft position sensor.

I’m currently in the process of trying to remove the torx bolt without heating it, and it is so seized that I may end up breaking the sensor if this goes wrong as I escalate my use of force.

While I hope to get it out in one piece to reolace the o-ring and switch the torx bolt for a hex head bolt, I’d really appreciate any information on this part if people have a part number or identifying info on it. It’s a 2004 rubicon with stock 241 transfer case. The images below are taken from the rear of the t-case on the driver side.

IMG_7229.jpeg


IMG_7235.jpeg
 
It is the speed sensor and yes it’s discontinued. You might try calling JB Conversions and see if they’ll sell you one of the ones from their super short SYE kit.

But first try just changing the o-ring. Probably can buy a generic o-ring kit at Home Depot that will have something that works. Hopefully the bolt comes out.
 
machoheadgames said:
It is the speed sensor and yes it’s discontinued. You might try calling JB Conversions and see if they’ll sell you one of the ones from their super short SYE kit.

But first try just changing the o-ring. Probably can buy a generic o-ring kit at Home Depot that will have something that works. Hopefully the bolt comes out.
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Thanks for the reply. That seems like the best plan so hopefully it goes well. I wasn’t sure about the part so that will save me a lot of time if I end up needing to get a new one.
 
I’d be hitting it with Kroil
for days….may be a long shot but corrosion with dissimilar metals can be tough. Might spray it on the back side repeatedly and let it climb.
 
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Hard to tell in the picture, but it looks like there's some gunk inside the head. Make sure that's cleaned out too so that the bit can get deep in there for more bite.
 
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machoheadgames said:
Good to see. I hadn’t ever seen that the one denoted camshaft sensor actually worked.
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Why would it matter? They are just a Hall Effect sensor that is triggered by proximity to moving metal. As long as they sense that, it shouldn't matter whether it is a 3 notch tone ring on an output shaft, notches on a flywheel edge, or slots in a flex plate rim. I'm guessing it is up to the PCM to figure out what to do with the various pulse counts regardless of where they originate from.
 
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mrblaine said:
Why would it matter? They are just a Hall Effect sensor that is triggered by proximity to moving metal. As long as they sense that, it shouldn't matter whether it is a 3 notch tone ring on an output shaft, notches on a flywheel edge, or slots in a flex plate rim. I'm guessing it is up to the PCM to figure out what to do with the various pulse counts regardless of where they originate from.
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Sensor data is sensor data no matter what. Probably one of the hardest things to get people to understand. Had dozens of people tell me i couldnt run a LS pcm on a tuned port manifold on a small block with coil on plug ignition because "it didnt come from the factory like that". Old g body cutlass would smoke the tires at 50mph with that setup.
 
Thanks guys. Got the bolt removed yesterday after cleaning it and hitting it with penetrating oil for a few days. I think it will be helpful for other people to see that the CPS works for this application though. Now I'm off to find a replacement O-ring to fit and I'll post the dimensions when I get it. Same with the replacement hex-head bolt. Funny enough I think even the dorman sensor does not come with an O-ring if you are to order one.
 
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When mine was leaking on my JB SSSYE, I bought a pack of o rings at the auto parts store. I found the best fit out of the pack and installed it with a little RTV ( tip from Mr Blaine)
 
Yeah I’ll try to get a viton ring if possible. The correct bolt is an M6x1.00x18mm. I used a 16mm length since that was all that was available at the hardware store, but 18mm is the factory length.

The old o-ring I removed seems to match perfectly with an o-ring I got from the hardware store with the following dimensions ID(inside diameter): 13/16”, OD(outside diameter): 1”. It has a section width of 3/32”. Both the old and new one with this dimension fit the sensor snug, so the ID seems perfect. However, when installed on the sensor, the sensor slides into the transfer case too easily, explaining the leak. This tells me the section width needs to be a hair larger. It’s possible that the previous owner put in an o-ring that was too thin after trying to fix a leak, but either way, I need a thicker one.

By the eye test, I’m guessing the following dimensions will be better: ID:13/16”, OD:1+1/16”, section width:1/8”.
I will keep the thread updated for others’ future reference.
 
kmac5130 said:
Yeah I’ll try to get a viton ring if possible. The correct bolt is an M6x1.00x18mm. I used a 16mm length since that was all that was available at the hardware store, but 18mm is the factory length.

The old o-ring I removed seems to match perfectly with an o-ring I got from the hardware store with the following dimensions ID(inside diameter): 13/16”, OD(outside diameter): 1”. It has a section width of 3/32”. Both the old and new one with this dimension fit the sensor snug, so the ID seems perfect. However, when installed on the sensor, the sensor slides into the transfer case too easily, explaining the leak. This tells me the section width needs to be a hair larger. It’s possible that the previous owner put in an o-ring that was too thin after trying to fix a leak, but either way, I need a thicker one.

By the eye test, I’m guessing the following dimensions will be better: ID:13/16”, OD:1+1/16”, section width:1/8”.
I will keep the thread updated for others’ future reference.
Click to expand...

I tried an SAE o-ring with a section width of 1/8” and it was too thick to allow the sensor to fit in its hole. Same with a metric o-ring with a width of 3mm which is just smaller than 1/8”. Seems like a width around 7/64” would work but they aren’t easy to find, and ordering them individually for $20 in weird sizes to test out just doesn’t make sense.

I really want to find the exact o-ring but I may end up using RTV with the one that fits but leaks. If I do find a ring that shows no leaks after a good test period I’ll update the thread.
 
For an o-ring, go to your local hydraulic shop, they’ll probably give it to you.
 
I think I found a good o-ring size. ID: 19.8mm OD: 24.6mm Section width: 2.4mm. I overlooked this one before because it seemed just barely bigger than the one that leaked like crazy. However, it is a very very tight fit. Does not want to go in without some moderate force. My only concern was that the o-ring might be so tight that it would want to fold, creating a seam for a leak to occur. I had atf on it and twisted the sensor back and forth while reinstalling into the transfer case to make sure it went in without binding up or twisting. I cleaned everything off and have been driving it a lot. Not a single spec of fluid showing around the sensor at all since. Bone dry. It's only been a week, but I will report back if it ever starts leaking again. The o-ring is available in the harbor freight blue metric o-ring set, but it also may be available in the viton material in other kits.

I also got someone at Dorman to confirm that their replacement sensor does not come with an o-ring. They told me they will add one to it, but I kinda doubt that will happen lol. Hopefully this info can help someone save some time in the future.
 
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