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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29396
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2002 GMC: crank sensor stuck..tranny local..dealership

Customer Question

I have a crank sensor stuck in a 2002 GMC 8.1L, I was able to pull the sensor up in-order to remove the o-ring, it spins but will not pull out. I have the tranny jacked up so I can grab it with a pliers, I do have the new one with me and everything tells me that it should just pull out. I have been using the PB Blaster for the last 2 days, it feels like theres another O-ring inside the block, my local GM dealership said NO, there is only 1. I have been wrenching on my own items for over 20 years.
Submitted: 6 years ago.
Category: GM
Expert:  Danny replied 6 years ago.
Ok my trick is use channel locks and twist sensor back and forth while at the same time use a pry bar to put pressure on it going out. it should come out for you then. put pressure on the channel locks if you cant get any of the sensor.
Customer: replied 6 years ago.
I've been using a 90 degree needle nose pliers and twisting and pulling, there isn't enough room to pry from underneath and apply even pressure and not snap the sensor.
Expert:  Danny replied 6 years ago.

OK you need channel lock needle nose pliers. use a big screw driver as you can get in there to put pressure on taking it out while you twist. You will have to put the twist and the pull at same time. This is the only way to get it out besides bits and pieces.


I did some extra checking for you and found the rand r for your crankshaft sensor.



Open. It may be a bit of waiting for the penatration oil to work now that you have twisted a bit and put some lube on it.


But pull and twist. when it comes out it wil act like it was neve stuck.

Customer: replied 6 years ago.
Thanks for spending the time to get that file. I had that printed out before I started working on the truck. This is one thing that I don't understand & says on that sheet:

If reusing the old sensor, Inspect the O-rings for cuts, cracks, tears or

damage, replace as needed. I have been told there is only O-ring at the top. I have the sensor out as far at the space for the O-ring (around 1inch or so) at that time is would spin freely and you could push it in and up to that point, then it's like it hits a wall and stops. Non of this makes sence, if it's the same as the new one, it should pull out. Now I am trying to find out how far past the block does the sensor stick out at the crank, I'm wondering if the sensor warped and is now caught on the end of the block and is trying to shave part of the sensor? also, is the hole in the block a smooth bore? From everything I have read, the sensor should be out by now. I am trying to find a motor out, pictures of the motor with the crank sensor sticking through etc, I need to know what I am up against. I have a friend making a bracket to weld on to the end of a vicegrip that matches the shape of the sensor and fits under the flange that rested on the block, this will give us 100 percent grip and no slipage, then something to pry on.

Expert:  Danny replied 6 years ago.
The mech next to me had one like that. I think he tried to breaking it out to soon. then he had to drop the oil pan. but thats on a 5.9 cummins. I have had then stick and I would just twist them with the channel locks and pry out at the same time. and for no reason pop out it comes after messing with it forever. The bore has a slot for the o ring.
Customer: replied 6 years ago.
So, whats holding it in?, rust? is the sensor warped?. Whats the reason it needs to be beat'n out? If I knew what I was up against, I can try and counter it. Rather not pull the motor.
Expert:  Danny replied 6 years ago.
its just that rubber o ring rubber o rings melt you can try to heat it up. but very carefully. I might just drive a thin screw driver beside it.
Customer: replied 6 years ago.
Relist: Incomplete answer.
I was not getting any more information than I already knew. He did do the best he could I guess, just not the information I was looking for.
Expert:  GM Tech (Cam) replied 6 years ago.

Greetings and Welcome to Just answer.

How far out of the block do you ahve it?


Customer: replied 6 years ago.
I would say 1", I can catch the spot for the O-ring with my fingure nail. Now it's like it hit a brick wall, we used a vise grip and pry bar to get it up the last 1/16" or so. Before doing that, it spun freely and pushed in/out the 1" just using our hand.
Expert:  GM Tech (Cam) replied 6 years ago.

Ok, does it push back in?

The way I do them is I twist when seated still then pry out with a small screwdriver keeping it straight.

We do have a tool, we took a connector and attached a wire to it so we can connect it and pull on that.


Expert:  GM Tech (Cam) replied 6 years ago.

Can you get a loop of small rope around it and then pull that or rig it up so a prybar pulls on the rope?


Customer: replied 6 years ago.

As of now we have not tried to push it back in after we started to pry. Before this it moved with ease. You used a connector with wires to pull?, my connector is now broke with 3 tabs sticking out. Do you know how far the sensor sticks through the block at the crank? From what I have heard and read, mine is doing something others have not. I did have 1 Tech tell me that the end could be swelled up from heat, thought he said it was like the 2.5 motors. Is the hole smooth from top to bottom?


Yes I did try the rope idea, the rope popped off twice, I had a ton of PSI on it before it came off. We are taking a vise grip and welding 2 half moon pieces to the end to grab under the flange that rests on the blocks so it does not slip while prying. It would be nice to know what I am up against and why it is doing what it is.

Expert:  GM Tech (Cam) replied 6 years ago.

As far as I know, about 1\8" actually sticks out inside the block.

It could have swollen up. The idea with the vice grip is a good one. Worst case is taking the pan off and driving it out from the bottom, but I have not had to do that.

Yes we used an old wire connector, but that does not sound like it will work. When I pry, it is against the tab with the bolt hole while pulling the other side to keep it straight.


Customer: replied 6 years ago.
Is there a way for you to find out 100% how far it stick through the block? 1/8" doesn't sound like alot or room, when I have heard a few time about pusing it into the pan. My thoughts with this, the sensing part of the sensor has to be close enought to the crank or a tab on the crank to pick up a signal. or is there only 1 or 2 spots that spin by, like a fan blade? I wish I could find a picture of one sticking through the block and the hole.
Expert:  GM Tech (Cam) replied 6 years ago.

You cannot push it back into. The sensor reads off a reluctor wheel on the back of the crankshaft.

This picture shows a tube in the block at the 10:00 that is the tube the crank sensor is in . This is looking down at the back of the block.



Customer: replied 6 years ago.
that hole is still inside that picture, it's not showing the crank side of the opening?
Expert:  GM Tech (Cam) replied 6 years ago.

No, but is shows how close this gets to the back of the crank. Pushing the sensor is in not an option unless you remove the crankshaft.


Customer: replied 6 years ago.

Ok. I need to find a magic wand to hold in one hand and a bible in the other, am I understanding this right?


So my only option right now is to grab it as safely as I can, pry it as safe as I can, then lube the heck out of it and hope to god it doesn't break?

Expert:  GM Tech (Cam) replied 6 years ago.

I am not sure what to tell you. Did you push it back down? There is an oring down lower and I have seen where there is debris caught between and I suspect that is why it will not move. I wish I could wave the magic wand but..........

Customer: replied 6 years ago.
Now, I have not found any info or Pic's to prove a second Oring, the service sheet says "oring's", I had the local GM parts guy look it up and it shows only 1 Oring to replace. Do you have or can you get me a Pic of the stock or orgional sensor that has a second oring? it doesn't feel like it hits a oring, if feel very solid like the plastic of the sensor.
Customer: replied 6 years ago.

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