Knock Sensor
Thread Starter
Safety Car
Joined: Nov 2008
Posts: 4,328
Likes: 15
From: Jacksonville FL
Knock Sensor
Finally got a new knock sensor for my '85. Needless to say the one that has been in the car for 28 tears is akin to being welded in the block. Any secrets besides a longer cheater to get it out? I just tried a 1/2" ratchet and stopped trying until I had a new KS in hand. The block plug on the opposite side is also stuck. I tried an 18" breaker bar but couldnt get a good angle on it. I want to get both out to drain all the coolant and refill with distilled water and antifreeze.
TIA!
TIA!
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
The plug on the driver's side is pipe threads, so it is tapered. The position of both the plug and the knock sensor make using a penetrating fluid difficult. Your trying to get the fluid to run up hill and there is usually a sealant on the threads of both.
Try using the penetrating fluid and let it sit for a day. Then the breaker bar (and cheater extension if needed) and a six point socket on each. Be aware that you might remove both and nothing will come out of the holes especially since they have been there for 28 years. The interior of the block tends to form a light coating of rust over the years. You will probably have to use a screwdriver of small punch to break thru the rust. Then the coolant will flow very well.....keep your mouth closed
and wear safety glasses.
Try using the penetrating fluid and let it sit for a day. Then the breaker bar (and cheater extension if needed) and a six point socket on each. Be aware that you might remove both and nothing will come out of the holes especially since they have been there for 28 years. The interior of the block tends to form a light coating of rust over the years. You will probably have to use a screwdriver of small punch to break thru the rust. Then the coolant will flow very well.....keep your mouth closed
and wear safety glasses.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
I have had to heat the block with a torch...around the sensor or plug. It will not hurt anything (except the paint) because the water in the block will not allow the casting to get too hot.
I would sue a 6 point socket for the left plug...and a 6 point metric socket on teh knock sensor. If the knock sensor spins...due to the staking has given away. I then go to a monkey wrench and use it along with a pipe. It will ruin the sensor...but it will get it out.
I have encountered WELL over 20 cars with the same TIGHT plugs due to never being serviced.
DUB
I would sue a 6 point socket for the left plug...and a 6 point metric socket on teh knock sensor. If the knock sensor spins...due to the staking has given away. I then go to a monkey wrench and use it along with a pipe. It will ruin the sensor...but it will get it out.
I have encountered WELL over 20 cars with the same TIGHT plugs due to never being serviced.
DUB
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The holes that the knock sensor and the plug on the opposite side go in have been there since 1955. On my car with the Z51 oil cooler there is a fitting on the driver's side that connects to the oil cooler.
I saw an interesting picture a few months ago where the poster broke his knock sensor while getting it out. It had a plain ol' pipe plug that was welded to the metal shell of the sensor part.
I recently did a complete flush of my cooling system and I bought a new knock sensor because I figured I would destroy the old one getting it out. The old one came right out after being in there almost 28 years, no problem. Another thing that surprised me was that there was no crud in the bottom of the water passages in the block. I had a '57 Chevy and pulled out a plug and nothing came out. I poked the hole with a screwdriver and got a face full of water...
I saw an interesting picture a few months ago where the poster broke his knock sensor while getting it out. It had a plain ol' pipe plug that was welded to the metal shell of the sensor part.
I recently did a complete flush of my cooling system and I bought a new knock sensor because I figured I would destroy the old one getting it out. The old one came right out after being in there almost 28 years, no problem. Another thing that surprised me was that there was no crud in the bottom of the water passages in the block. I had a '57 Chevy and pulled out a plug and nothing came out. I poked the hole with a screwdriver and got a face full of water...
