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Hey all,

First, Merry Christmas to everyone!

So here it is. I started yesterday to change the heater core in my 95 Roadmaster. Everything was going great. I even removed the screw at the firewall side of the heater box without much difficulty.

Not willing to leave good enough alone, I decided to pull the knock sensors so I could get rid of any crap in the engine block.

First one came out easy. The second one on the drivers side stripped. When I say stripped, I mean the sensor itself, not the threads in the block.

I applied heat carefully. I tried a vise grip on the sensor and turned the vise grip with a wrench. I felt like I had a good amount of force before it slipped off, but the sensor threads didn’t budge.

I decided to reattach the sensor wires and start the engine, no problem, started right up with no codes, although I only ran it for a minute.

Last thing I did was spray some PB Blaster on it and called it a night. Even in Florida the grass was getting cold lol.

So here’s my question, can I just drain the other side, hook both of them back up, and forget this happened for now?

I need to go to Virginia, probably within a couple weeks, and I really don’t want to make the car undrivable when I don’t have the time to mess with it.

Obviously I need to deal with it eventually, but am I correct in thinking this isn’t something that can leave me on the side of the road, presuming I drive the car around locally for a few days without throwing codes?

The fitting doesn’t appear to be leaking. I did try hitting it with a chisel to dent it so the hex would grip, but that didn’t work either.

Appreciate your thoughts. The picture has PB Blaster dripping from the sensor, not coolant.

Thanks all, hope you all have a great Christmas.




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I don't think it would cause any issues being left like that for a little while, especially if it still seems to be functioning fine. I had a mother of a time pulling mine back when I did my 24x conversion (different knock sensors are required for the 0411 pcm) but I did get them without too much drama. A couple things come to mind, you are using a 6 point socket and not a 12 point, right? A 12 point won't grip as well and has a better chance of rounding off. Once you're committed to getting it off, I wouldn't be opposed to taking an impact to it. If you can't get the correct socket to fit tightly anymore, see if there's one close that's a little smaller. I don't remember if those are standard or metric, but if it's say 3/4", try 19mm which is a hair smaller, and hammer the socket on if you need.


And if that fails, I do believe I've heard of a couple people ripping the sensor right off, (usually from it just giving up under the strain of a breaker bar and a cheater pipe) you'd then have access to remove what's left. Drill it, split it with a chisel, whatever it takes, and then run a tap through it. It's just a common pipe thread I think. And then pump a bunch of water through the system to flush out any shavings or debris if it came down to that. I read a tip not too long ago about packing a tap with grease before running it into a hole you don't want to have shavings fall into, they mostly stick to the grease instead, plus it acts as your lubricant when chasing the threads. But yeah, if it's not looking leaking now and running fine, I'd let it be for now.


Even if it isn't functioning correctly, the car is either pulling timing which won't hurt anything, (which I doubt would even be the result of this) or it isn't pulling enough, but as long as you're not hot rodding it on the street or going to the drag strip before repairing it, you probably won't be running it hard enough that it would need the knock sensor to indicate a knock anyways. Besides, if one side of the engine is pinging, the other side probably is too, and you have a good one on the other side. In fact I recently learned that the f-body LT1's only ran 1 knock sensor because something prevented one from being installed on the other side, not enough clearance. Tighter packaging on those though, so not a big surprise. I think running one on both sides is just insurance against one failing.
 

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I had one that would not come out and did exactly what yours did. I was able to get a pipe wrench on it and it spun right out. Mine is a LO5 and was out of the car. You may have to use a small pipe wrench and a cheater to loosen it up. With that, I would think as you suspect and Schlicky said, I'm betting you will be fine for the time being. Best of luck.

Mark: Snowman-33
 

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I know when the air temps in Florida drop to 70F it is so funny that locals have the new england winter jackets on ... I will be in Ocala end of next month ..

knock sensors can not be whacked .dropped , shocked etc.. these produce a voltage when the engine makes metal whacking then the PCM retards timing etc..

I was told over 20yrs ago to put some thread sealant on the threads a small amount of paste like paint not load goop ...I used a teflon gas pipe thread paste .. also perhaps someone over torqued those sensors .. I only put 10-15 ft lbs on these and never had a leak or any problems removing . I do remove these every 3-4yrs when I do the coolant / heater core flush . I replaced the radiator this year because the plastic diver side tank had a crack near the upper hose .. radiator looked new no discoloration 65% dexcool 35% distilled water ... did this when the car was 2 yrs old reason is the heater did not work my toes too cold .. GM did not use clean distilled water .. so I had to do this process .also washed out the mess in the plastic tank ..

as was mentioned use a small pipe wrench on the pipe portion ..since you whacked it not sure how hard you hit it , good to replace that one ..

many on here will not like my thread paste comment but no problems for me... more is not better just need a small amount will not effect the sensor .
 

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Discussion Starter #5
Thanks everyone for all the replies. It’s very encouraging to know I should still be ok to drive the car.

As advised I’m going to look for the smallest pipe wrench I can find and give that a try.

It would be a nice time to have a crows foot pipe wrench with an insert opening for a socket extension! Only problem nobody makes one haha.

Thanks again and Merry Christmas!


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Discussion Starter #7
Good advice on the small pipe wrench. I found one this morning in my tools. I’m going to try that.

I also just bought these:
IMG_0841.jpg

As far as skinning the cat, here’s mine :)

IMG_0653.jpg


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No insult intended.
The other day I was going into Walmart. There was a woman in front of me with a dog on a lead. I was about 6 foot behind her. The dog all of a sudden turned around and lunged at me barking and raising hell. The greeter was there and I said "That's not a service dog". I guess they agreed because the dog was not allowed in. The woman said that her dog only did that if someone got close to her. Well damn, I guess she thought she should have a clear path through the entire store. I'm a dog person. I have three, Chevy, Harley, & Mini. I hope you get that KS out without too much difficulty.

Mark: Snowman-33
 

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No insult intended.
The other day I was going into Walmart. There was a woman in front of me with a dog on a lead. I was about 6 foot behind her. The dog all of a sudden turned around and lunged at me barking and raising hell. The greeter was there and I said "That's not a service dog". I guess they agreed because the dog was not allowed in. The woman said that her dog only did that if someone got close to her. Well damn, I guess she thought she should have a clear path through the entire store. I'm a dog person. I have three, Chevy, Harley, & Mini. I hope you get that KS out without too much difficulty.

Mark: Snowman-33


Yeah the whole therapy animal thing has gotten out of hand. Therapy dog, cat, goose, snake... lol.

I didn’t think you wanted to skin my cat lol. Not sure where that expression came from... well, they do eat them in China.


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Also, make sure you have a new sensor on hand before you tackle it again. I just removed and replaced mine earlier this year for a radiator R&R. It was the first time I had ever removed them. There was a lot of gunk that came out. I used Standard Motor KS2 sensors and teflon tape.
 

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THANKS EVERYONE FOR THE ADVICE!

Got that friggin thing out. Pulled the plug wire above it, used a pipe wrench, with me holding it in place, and my friend pushing the wrench with a cheater bar from above.

I was worried we were twisting it of with the threads still in the block, but it came out clean.

Surprisingly, no coolant ran out when it came out on that side, but did on the other. I pushed in a plastic reamer and opened it up. Then I ran some water through the engine by putting it in the coolant overflow tank.

You can see from the pic why I had no heat, lots of crud in the core.



Anything else I should do before I put it back together?


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your engine looks like new but that coolant goop is nasty nasty... I have never seen that on any engine I have ever owned ..

remove the T stat and with the kS removed stick water hose into the T stat bore hole and flow until all the crap is out .. may take a long time .. also my concern is radiator , stick hose in top hose hole and do the same until all that mess comes out ..with lower rad hose removed ..



looks like Ocala tap water was used in that coolant .. only use distilled water when you use your same coolant type .. changing coolant types does cause these nasty coolant mess jobs also..


good you did follow the suggestions using the small pipe wrench ..
 

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So happy that it worked out for you. That sure was a nasty looking mess in there. I'm sure you're following the flush suggestions and getting it good and clean. I've used the pipe wrench for removing broken studs and bolts that the head got mangled up.

Mark: Snowman-33
 

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Discussion Starter #14
your engine looks like new but that coolant goop is nasty nasty... I have never seen that on any engine I have ever owned ..

remove the T stat and with the kS removed stick water hose into the T stat bore hole and flow until all the crap is out .. may take a long time .. also my concern is radiator , stick hose in top hose hole and do the same until all that mess comes out ..with lower rad hose removed ..



looks like Ocala tap water was used in that coolant .. only use distilled water when you use your same coolant type .. changing coolant types does cause these nasty coolant mess jobs also..


good you did follow the suggestions using the small pipe wrench ..


Good idea with the T stat. I put the hose in one of the heater core hoses until clean water came out the other one. I’ll do as you suggest for the Tatar and radiator.

I’m wondering if I should stay with Dexcool, it looks like that’s what was in there, MOSTLY...

I do plan to rinse everything really good though.


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So happy that it worked out for you. That sure was a nasty looking mess in there. I'm sure you're following the flush suggestions and getting it good and clean. I've used the pipe wrench for removing broken studs and bolts that the head got mangled up.



Mark: Snowman-33


Yeah the pipe wrench is it. I think I need to invent a crowfoot pipe wrench. It would’ve been perfect for this job, it just doesn’t exist.

A little cutting and welding perhaps. :)


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I am just guessing !!! looks like someone put a universal grade coolant that says compatible with ALL coolants .. mixed in with DEXCOOL .. if so that is why it is a nasty mess..

if you do all the work on your vehicles then you will not need a label stating only Dexcool on the plastic pressure tank cap ..

if this is what happened you may have to go thru this again ..remove T stat then ,
run the engine and then drain the block until the water comes out clear .. also wash out that plastic tank .. I remove the tank and use patio vinyl cleaner .. it takes a while to breakdown that mess.. in the tank .. cover the opti with some plastic when the goose neck removed
 

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I am just guessing !!! looks like someone put a universal grade coolant that says compatible with ALL coolants .. mixed in with DEXCOOL .. if so that is why it is a nasty mess..

if you do all the work on your vehicles then you will not need a label stating only Dexcool on the plastic pressure tank cap ..

if this is what happened you may have to go thru this again ..remove T stat then ,
run the engine and then drain the block until the water comes out clear .. also wash out that plastic tank .. I remove the tank and use patio vinyl cleaner .. it takes a while to breakdown that mess.. in the tank .. cover the opti with some plastic when the goose neck removed

I think you’re correct on the mixing of the coolants. When I bought the car the seller didn’t know. What was in the overflow tank was in between lol...

When I drained the block it looked more like dark Dexcool than anything else.

I rinsed VERY thoroughly, per instructions received here. :) I’m ready to do it again if needed. Everything flowed clear eventually.



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Discussion Starter #19
Another question :)

I bought a new thermostat housing just in case. So when changing the thermostat and doing the Lowe’s bleeder valve mod, I noticed that there’s no gasket under the thermostat housing, although there’s on in the box with it. Of course there is the rubber O ring on the thermostat itself.

It wasn’t leaking without the PAPER gasket... I seem to remember reading somewhere that that paper gasket shouldn’t be used.

Anyone know about this?

Thanks






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