I was putting the driver's side knock sensor back in my LT1 today and it was just really hard to turn about halfway (when it hit the orange thread sealant leftover from the original factory install). It wasn't cross threaded, because I took it out and put it back in several times, each time it was easy to turn by hand until it hit the thread sealant. So, I got a little bigger wrench and pushed on. Well, it got really really hard to turn so I stopped and checked the back side with a mirror and saw that I was still a good 1/4" from being fully seated. At this point I decided to clean the thread sealant off, so I started to unscrew it from the block. That's when it got really really easy to turn. And that's when I realized that the head part (with the flats for the socket) was spinning inside the cup of the main body of the sensor. It looks like the body of the sensor is just crimped over the grooved edge of the top with the wrench flats. That part isn't holding any more, it's just turning inside the body.

I'm stuck. Does anyone have anyone have any advice or trick as to how to get this thing out of the block????? Maybe use some epoxy or JB weld to glue the two pieces together? Solder? (gonna be hard with it upside down) Try using a punch to peen the edge tighter into the crimped lip?

HELP

 

My suggestion would be to use a hacksaw or dremel with cutoff wheel to cut off the stamped-metal "head" of the sensor, leaving behind the threaded portion. Then, you can grind 2 sides of the threaded portion flat, and use an open-end wrench to remove. Also, soak threads well in pb blaster or equivalent penetrating oil.

 

Ok, here's plan A. I can get the tip of a punch on about half of the circumference around the outer edge, and can sort of swing a hammer at it, so I've tried to peen down that outer lip some more to see if that will give me enough bite to get the sensor past the thread sealant on the threads. I also think I'm going to go ahead and fire the engine once I get the new Opti bolted, balancer, and the rest of the front buttoned up (no water pump). Maybe the heat in the block will make it easier to turn the thing out.

I just knew this day started off too smoothly...

 

If I'm telling you something you already know, please know I don't mean to condescend...my impression from your original text is that you're expecting the sensor's threads to seat completely in the block. This sensor has tapered pipe threads and not machine threads; it is threaded into a location that would just have a drain plug if the sensor wasn't necessary. You should just tighten it enough to seal.

Can't help you much with how to get it out; can you get a pipe wrench on the body? Vise Grips? But one thing I would recommend is that you don't attempt to glue it back together...it's an important sensor and I wouldn't trust it.

 

You know, you're right. I vaguely remember reading about the tapered threads way back when I was doing a full coolant drain in my '96 LT1 Caprice. I feel like a bonehead now.

I can't get vice grips or a pipe wrench on it to turn unless I remove the oil pan. I do NOT want to go through that headache at this juncture.

I supposed I'm going to write off this sensor. Like you said, I won't trust it, and I wouldn't want it to get stuck in the block again if I decided to re-use it.

 

Not only do you not want to get it stuck, it does an extremely important job...if your spark controller doesn't get the signals from it to retard the timing when detonation occurs, you can do major internal damage.

Since you can get a hammer and punch to it, try using the punch to turn the case. You want to have the punch striking the outer perimeter at an angle such that each blow of the hammer rotates the sensor counterclockwise a little bit. Use a center punch with a sharp point so it doesn't "skid" off of the sensor but turns it as it digs in. This is a tried and true old trick for loosening a stuck bolt, especially one with the corners rounded off of the head.

 

I thought about that, but with that oil pan in the way, and the exhaust, I can't really get the right angle on the punch to be able to hit the sensor from the side. I can only hit it on the face, perpendicular to the block.

This is a real bugger. I put some water into the block and it's not leaking out, so that's good. I'm going to start the engine to verify the new Opti is good, and then after the engine has some heat in it I'll try to turn the sensor again.

 

I just had an idea; go to home depot or such and get a "basin wrench" and see if that won't do it; I'm betting it will.

Do a search on YouTube for basin wrench; first video shows how it works.

 

You may have to introduce a little heat from a propane torch to get it to back out... When you put the next one in,torque it to the specified torque spec.. If these aren't torqued to the right number they may not have the proper sensitivity or may not work at all...Ask me how I learned this?....WW

 

Torque spec is low, something like 15 ft/lbs

 

THAT IS FREAKIN' AWESOME. I never knew such a thing existed. I bet that will work. I'll look into it tomorrow.

I got the car started with the new Opti, with no water pump. Idles nice. The only code it threw was a coolant temp sensor code, which makes sense because that wasn't connected.

I put the new water pump on. Boy, what a beeyotch, that thing was a lot easier to take out when I wasn't trying to be extra careful to not get gasket RTV on everything while it was being maneuvered into that confined space.

I'm going to fire it up again tomorrow to check for leaks, and let it run through some heat cycles to get the gunk in the cooling system loosened up so I can drain it. While the engine is hot I will make another attempt to extract that knock sensor.

Will I get a code from the computer if that thing is busted? I know I won't get anything if it's just not installed properly and not picking up anything.

 

Yep, and I should have known that, since I've looked up that torque spec before. RTFM