C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Knock Sensor Question

Thread Tools
 
Search this Thread
 
Old May 2, 2006 | 07:26 PM
  #1  
cmontel727's Avatar
cmontel727
Thread Starter
Racer
20 Year Member
All Eyes On Me
Liked
 
Joined: May 2004
Posts: 295
Likes: 3
From: Newton NJ
Default Knock Sensor Question

I replaced my knock sensor this weekend and excepted to get soaked with coolant, but it didn't happen. Is this something to be worried about? There was just a small amount on the sensor itself and a little inside the block. The car was on jack stands and I did not drain any coolant before hand.

Car is an 87 l-98 auto, knock sensor came up bad following FSM testing. I'm not having a cooling issues, just had occasonial engine knock under load. Since replacing the sensor all is good according to my ear and datamaster.

TIA

cmontel
Reply
Old May 2, 2006 | 07:33 PM
  #2  
CFI-EFI's Avatar
CFI-EFI
Race Director
10 Year Member
 
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Default

The knock sensor threads into the block drain hole in the right side of the block. Your description is one of "deferred maintenance". When is the last time, and how often, do you thoroughly flush your cooling system? The only thing that prevented your taking a shower was rust flakes and sediment blocking the drain hole.

RACE ON!!!
Reply
Old May 2, 2006 | 07:48 PM
  #3  
cmontel727's Avatar
cmontel727
Thread Starter
Racer
20 Year Member
All Eyes On Me
Liked
 
Joined: May 2004
Posts: 295
Likes: 3
From: Newton NJ
Default

I changed the coolant last summer, when I replaced the water pump. I have only owned the car for two years. I'm not sure if the prior owner did any maintenance, it seems like the car was barely touched. Everything looked original including all the fluids.

I quess I will be changing the coolant and again this summer using a my local mechanic and a power flush system.

Thanks for the quick reply CFI-EFI
Reply
Old May 2, 2006 | 08:23 PM
  #4  
CFI-EFI's Avatar
CFI-EFI
Race Director
10 Year Member
 
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Default



RACE ON!!!
Reply
Old May 3, 2006 | 03:56 AM
  #5  
CentralCoaster's Avatar
CentralCoaster
Team Owner
 
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Default

Mine had solid metal behind it. (Surely CFI will tell me I'm hallucinating). Perhaps the holes didn't make it all the way into the water jacket on some blocks. Yours obviously had at least some opening, but maybe not much.
Reply
Old May 3, 2006 | 08:11 AM
  #6  
cmontel727's Avatar
cmontel727
Thread Starter
Racer
20 Year Member
All Eyes On Me
Liked
 
Joined: May 2004
Posts: 295
Likes: 3
From: Newton NJ
Default

Well that makes me feel a little better... I was picturing a block full of sludge, maybe it's half-full instead.
Reply
Old May 3, 2006 | 08:15 AM
  #7  
Pete K's Avatar
Pete K
Race Director
20 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Feb 2004
Posts: 12,517
Likes: 19
Default

Originally Posted by CentralCoaster
Mine had solid metal behind it. (Surely CFI will tell me I'm hallucinating). Perhaps the holes didn't make it all the way into the water jacket on some blocks. Yours obviously had at least some opening, but maybe not much.
I had 2 blocks like this. It appeared that they were not drilled completely through. I took a punch and twanked the thin piece of metal out. It allowed for complete draining of the block.
Reply
Old May 3, 2006 | 08:30 AM
  #8  
CMYC4GO's Avatar
CMYC4GO
Melting Slicks
 
Joined: Mar 2003
Posts: 2,898
Likes: 0
From: Oklahoma City Oklahoma
Default

My car is meticulously maintained, especially the fluids. When I changed out my knock sensor, I might have gotten three drops of coolant on the driveway. I too expected a shower, but I'm not going to look a gift horse in the mouth.
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

 Joe Kucinski
story-1

8 Coolest Corvette Pace Cars (and Replicas) of All Time

 Verdad Gallardo
story-2

Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

 Joe Kucinski
story-3

Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

 Verdad Gallardo
story-4

Top 10 Corvettes Coming to Mecum Indy 2026!

 Brett Foote
story-5

Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

 Michael S. Palmer
story-6

10 Revolutionary 'Corvette Firsts' Most People Don't Know

 Joe Kucinski
story-7

5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

 Michael S. Palmer
story-8

2027 Corvette vs The World: Every C8 vs Its Closest Competitor

 Joe Kucinski
story-9

10 Most Common Corvette Problems of the Last 20 Years!

 Joe Kucinski
Old May 3, 2006 | 07:48 PM
  #9  
cmontel727's Avatar
cmontel727
Thread Starter
Racer
20 Year Member
All Eyes On Me
Liked
 
Joined: May 2004
Posts: 295
Likes: 3
From: Newton NJ
Default



Thanks everyone for your posts!! I will flush and refill my coolant and call it day on this issue. Sounds hopeful that the insides of my engine are not a total mess
Reply
Old May 3, 2006 | 08:16 PM
  #10  
CorvAdel's Avatar
CorvAdel
Racer
15 Year Member
 
Joined: Nov 2004
Posts: 445
Likes: 0
Default

Originally Posted by cmontel727


Thanks everyone for your posts!! I will flush and refill my coolant and call it day on this issue. Sounds hopeful that the insides of my engine are not a total mess
Let's hope so...however, I once stripped an engine to find a gel-like substance in the coolant passages low in the block. Turns out that previously two different coolants had been used without the first one being completely removed. Seems that some coolants cannot live with each other and react by forming a sludge....this would stop coolant from draining...
Perhaps when you flush your coolant, it might be an idea to remove your ks again and pry in to it's recess to see what is in there...!
Reply
Old May 3, 2006 | 08:44 PM
  #11  
CFI-EFI's Avatar
CFI-EFI
Race Director
10 Year Member
 
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Default

Originally Posted by CentralCoaster
Mine had solid metal behind it. (Surely CFI will tell me I'm hallucinating). Perhaps the holes didn't make it all the way into the water jacket on some blocks. Yours obviously had at least some opening, but maybe not much.
Call it (hallucinating?) what you like. I have had several that it took pounding with the heel of the palm if my hand on the screwdriver handle to break through. That sediment and rust can get pretty solid. Do you really think they use a special "bottoming" NPT tap on those drain plug holes, just to fool people? And if you don't believe they are drain plug holes, why do you think they have been there longer than a "knock sensor" was a gleam in it's inventor's eye?

RACE ON!!!
Reply
Old May 4, 2006 | 09:11 AM
  #12  
aboatguy's Avatar
aboatguy
Race Director
15 Year Member
 
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
Default

Was your system sealed when you pulled the sensor? I have removed knock sensors on my car and if I leave the pressure cap on I can remove and replace the sensor without getting douched. Now if I remove the cap the water streams out instead of dribbling .
Reply
Old May 4, 2006 | 11:42 AM
  #13  
91 steel blue's Avatar
91 steel blue
Intermediate
10 Year Member
 
Joined: Apr 2002
Posts: 48
Likes: 0
From: corbin ky
Default

sludge and rust scale is what it is. once again cfi-efi is correct. i just removed knock senser and block plug yesterday and no antifreeze would drain. it looked like solid metal in there. when you start probing and scraping the recess of the bolt hole, be sure to have eye goggles on. there's alot of fluid in there.
Reply
Old May 4, 2006 | 11:54 AM
  #14  
js292's Avatar
js292
Burning Brakes
20 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Jan 2005
Posts: 847
Likes: 1
From: spring branch texas
Default

My did drain, with the engine on the stand I forgot to pull the sensor outside when I pulled the motor and once in the garage I pulled it and made a big ol' mess
Reply
Old May 4, 2006 | 07:59 PM
  #15  
GRX's Avatar
GRX
Le Mans Master
20 Year Member
 
Joined: Jul 2001
Posts: 6,252
Likes: 2
From: Silicon Valley Kalifornia
Default

Also, I've read that GM does not recommend retorquing the knock sensor. (read: don't re-install it).
Reply

Get notified of new replies

To Knock Sensor Question





All times are GMT -4. The time now is 05:05 AM.

story-0
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-1
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE
story-2
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

Slideshow: Ranking the top 10 Corvette engines by torque output.

By Joe Kucinski | 2026-05-05 11:58:09


VIEW MORE
story-3
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

Slideshow: A Corvette pace car nearly matching IndyCar speeds sounds exaggerated, until you look at the numbers.

By Verdad Gallardo | 2026-05-04 20:03:36


VIEW MORE
story-4
Top 10 Corvettes Coming to Mecum Indy 2026!

Among a rather large group of them.

By Brett Foote | 2026-05-04 13:56:44


VIEW MORE
story-5
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE
story-6
10 Revolutionary 'Corvette Firsts' Most People Don't Know

Slideshow: 10 Important Corvette 'firsts' that every fan should know.

By Joe Kucinski | 2026-04-29 17:02:16


VIEW MORE
story-7
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE
story-8
2027 Corvette vs The World: Every C8 vs Its Closest Competitor

Slideshow: 2027 Corvette lineup vs the world.

By Joe Kucinski | 2026-04-24 16:12:42


VIEW MORE
story-9
10 Most Common Corvette Problems of the Last 20 Years!

Slideshow: 10 major Corvette problems from the last 20 years.

By Joe Kucinski | 2026-04-14 16:37:05


VIEW MORE