[tommy evans]

Own a 1987 Chevy 5.7 suburban and having BIG! difficulties attempting to remove the knock sensor from the engine block. Tried loosening it with a breaker bar and chicken out when it wouldn't budge.Sprayed it down with WD-40 and Liquid Wrench and gave up for the day. I am very worried about busting the unit off. I thought about using a small propane tank to heat the unit up, but the thought of gasoline kind of ruin that thought. I used a half inch drive socket with a few extensions in my effort to remove the unit, but as I said before with no luck. I could get lucky tomorrow if the penetrating oil does it job, but in the mean time I figured I'd fire a thread off to ya'all and find out from past experience if there are any tricks of the trade that would help me get this unit successfully removed. Are there any special tools I should be aware of? Any methods other than what I have already tried? I'll be waiting for your replies, thanks.

Tommy

[evolvo]

You might try using a ball peen hammer to tap tap tap on the block where the threads are. Do this for a least a couple of minutes or longer. The vibrations may help loosen the grip of the threads. Then use a breaker bar with a medium but steady pressure on the KS.
Unless you have gas pooled on the floor a propane torch should be OK. Just be careful!
Good Luck

[tommy evans]

My research on how to get a froze up knock sensor has led me to finding out what is the best penetrating oil to use to break the item loose. Kroil brags pretty extensive, a few good words about liquid wrench but wd-40 is considered not a penetrating oil. What other good stuff is out there being marketed thats worth talking about? Your nod to use heat has put a little confidence in its use, of course you can bet I will have a fire extinguisher available. Last question; a buddy and I plan to remove the sensor without draining the coolant can we get away with it? Considering I might have to use heat, would the water in the block hinder the use of heat? Today when I made my first attempt my buddy told don't open the cap on the radiator. I guess he wanted to keep pressure on the system, but I am still puzzled why he told me this???? Plan to put the old breaker bar on the unit tommorow about 5:00 PM. Will be soaking it all day until that time. Keep those suggestion coming, thanks.

Tommy

[cobalt327]

Originally Posted by tommy evans

My research on how to get a froze up knock sensor has led me to finding out what is the best penetrating oil to use to break the item loose. Kroil brags pretty extensive, a few good words about liquid wrench but wd-40 is considered not a penetrating oil. What other good stuff is out there being marketed thats worth talking about? Your nod to use heat has put a little confidence in its use, of course you can bet I will have a fire extinguisher available. Last question; a buddy and I plan to remove the sensor without draining the coolant can we get away with it? Considering I might have to use heat, would the water in the block hinder the use of heat? Today when I made my first attempt my buddy told don't open the cap on the radiator. I guess he wanted to keep pressure on the system, but I am still puzzled why he told me this???? Plan to put the old breaker bar on the unit tommorow about 5:00 PM. Will be soaking it all day until that time. Keep those suggestion coming, thanks.

Tommy

The best penetrant by far is PB Blaster, IMO. It's 10X better than WD40. I had a buddy put it on a rusted nut and bolt holding on a battery terminal. He sprayed it, I came back not knowing what he'd done and almost hurt myself when the nut cam loose so easily- I swore he had already loosened it, but he hadn't. The **** WORKS!!!

But NOTHING will work unless it actually penetrates to the threads. That is where heat comes in.

If you carefully heat the block- NOT the sensor- then hit the joint w/the PB Blaster, there's a good chance that you'll get to the threads w/it. If it does, it will come off w/o issue. Don't breath the fumes, BTW.

Even just heating it can interrupt the seized threads by the difference in expansion and contraction.

[T-bucket23]

X2 on the PB blaster, it is amazing stuff. I have never used Kroil but I cant imagine it could be much better.

Patience is the key, spray, wait, spray wait. The hammering can help the oil penetrate as well as some mild heat.
Good luck!

[evolvo]

Originally Posted by tommy evans

Last question; a buddy and I plan to remove the sensor without draining the coolant can we get away with it? Considering I might have to use heat, would the water in the block hinder the use of heat? Today when I made my first attempt my buddy told don't open the cap on the radiator. I guess he wanted to keep pressure on the system, but I am still puzzled why he told me this???? Plan to put the old breaker bar on the unit tommorow about 5:00 PM. Will be soaking it all day until that time. Keep those suggestion coming, thanks.

Tommy

I guess you can take it out without draining the water, but........the KS works by reading vibrations in the coolant and therefore is screwed into a water passage. It acts like a plug when its in the hole and a drain when its out.
Drain the system down first, IMO.