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"knock-knock", or how NOT to fix an ESC sensor...

Joined
Oct 30, 2001
Messages
2,273
Location
Glen Burnie, MD, USA
Corvette
1986 Bright Red Coupe
Went to the dealer the other day to buy a new knock sensor, figuring to give that a go in my battle against the engine pinging I've suffered through.

Read some instructions, which said to drain the cooling system first. Heck, I said, how much coolant can there be in that part of the engine when it's cool and not running? I'll just remove the sensor.

So - lucked out with having a 22mm socket from another project. Placed a small bucket near to hand and crawled under the car.

First off, in order to retard spark, a knock sensor MUST BE HOOKED UP... Yep, that's right, the harness for the knock sensor was disconnected and tie-wrapped neatly out of the way so as not to hang on the exhaust and melt (which it apparently had at one time). Old knock sensor has broken connectors, probably why the harness wouldn't stay on, but WHY would someone deliberately disable it???

Anyway, worm my way around and unscrew the sensor. Blorp. Coolant comes out. Grab the bucket. Uh-oh. Coolant isn't flowing neatly out the hole but instead runing down the -starter, -transmission, -oil pan, - exhaust, etc. And guess what? It's not stopping!! Quick! Grab another bucket. Quick! Grab some shoprags. Quick! Make a dam on the garage floor. Oh crap, it's STILL not stopping. Just how much coolant is there IN this engine??

I think a good four gallons flowed out over the span of about 15 minutes. Oops... guess I'm changing the coolant today...

So finally I manage to get the new sensor in (there is NO room for hands above that starter, folks!) and realize that the end of the sensor harness is cracked and melted. It stays, but barely. Silver racing tape to the rescue...

This is apparently not a dealer-providable item. Anyone got a spare ESC sensor harness they don't need?

On the good side, there's only a tiny bit of pinging that quickly goes away and I can run the heck out of the engine with no pre-detonation, even with timing set back to where it should be (I hope). And it seems to start MUCH easier.

So hopefully that'll take care of my anti-performance issues...

[RICHR]
 

barrier5

Well-known member
Joined
Dec 27, 2001
Messages
126
Location
janesville wi usa
Corvette
1982 bright blue coupe
Didn't yoou ever read the story of the little dutch boy? You should be able to rob a sensor wire off any 84 or later GM car or truck,but if you cant get find one,EMail me I have one with about a foot of wire hanging off you could splice in.
 
Joined
Oct 30, 2001
Messages
2,273
Location
Glen Burnie, MD, USA
Corvette
1986 Bright Red Coupe
barrier5 said:
Didn't yoou ever read the story of the little dutch boy? You should be able to rob a sensor wire off any 84 or later GM car or truck,but if you cant get find one,EMail me I have one with about a foot of wire hanging off you could splice in.

Hey.. I'm not planning on sticking my finger into any dyke. Er, dike. Anyway, if I'd tried to put the sensor in while the coolant was still flowing, I'd have wound up with a mouthful of glycol - only way I had clearance to fit the part was to lie on my back directly underneath the starter and worm my arm around the exhaust.

I'm going to hit the local auto recycler tomorrow; if they don't have the harness, I may indeed take you up on your offer.
Thanks,
[RICHR]
 
V

vetsvette

Guest
BLORP?

Good story. Just for future reference: to completely drain your coolant, I think step 2 is remove knock sensor. I was going to do it myself but after reading your story I think I'll farm it out. It's probably not as funny when it's happening to you.:gap
 
Joined
Oct 30, 2001
Messages
2,273
Location
Glen Burnie, MD, USA
Corvette
1986 Bright Red Coupe
It probably looked pretty darned funny to anyone watching... guess I'm glad there was no camcorder handy :)

I have a feeling that if you first drain the majority of the coolant via the radiator's draincock, there won't be a heck of a lot to come through the knock sensor. Just don't take the sensor out first... unless you're parked over a trashcan!

Barrier5, thanks for the offer - I did manage to get one locally. I thought to bring along the old sensor and just say "find me something from a GM engine that fits this" and they did.

[RICHR]
 

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