Q: Knock Sensor Boss Issue
Q: Knock Sensor Boss Issue 
Lock sensor issue
hello,
i recently purchased a running L33 from a auto wrecker for a great price. Upon taking the knock sensor and valley cover off I uncovered quite the interesting issue pictured below:
My question is, how can I fix this issue? Does GM make a replacement part for this? Does this remove from the block or is it part of the casting?
Thanks in Asvance for all the insight you can provide!
- Don
Last edited by DonH; Oct 6, 2018 at 03:26 PM.
i don’t plan on a complete tear down or else I would. I was planning a quick cleanup, new HG and go... :/ I can clean the area really well and probably have a sleeve rig welded over.
Bump for some ideas on how to fix this.
I was thinking an aluminum bung welded to the bottom portion of the boss. Any other ideas? It looks like these are one piece on the block also.
I was thinking an aluminum bung welded to the bottom portion of the boss. Any other ideas? It looks like these are one piece on the block also.
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It's old seal/rubber
After many years they get really hard and break off like that when you pull the valley cover. Chip at it with a chisel or screwdriver, then use some 300-400 grit or so to clean it up and make the sealing surface smooth and clean again.
After many years they get really hard and break off like that when you pull the valley cover. Chip at it with a chisel or screwdriver, then use some 300-400 grit or so to clean it up and make the sealing surface smooth and clean again.
Thank you for your kind and insightful response! Much appreciated! I noticed the other BOSS was much larger in diameter and was worried the gunk was actual metal that somehow rotted away. I will use my dremel and begin to clean it up. Thanks so much!!!
OP (CattleAc you may already do this..?) I take a socket that barely fits around the boss after cleaning it up and when I set the valley cover on I push the seals down gently with the socket and kinda pull everything down and close that way instead of forcing the valley cover down and hoping the seals pull onto the bosses. Yup, learned that AFTER tearing a set lol.
OP (CattleAc you may already do this..?) I take a socket that barely fits around the boss after cleaning it up and when I set the valley cover on I push the seals down gently with the socket and kinda pull everything down and close that way instead of forcing the valley cover down and hoping the seals pull onto the bosses. Yup, learned that AFTER tearing a set lol.
SO let me ask you this, why is one BOSS much thicker than the other? This BOSS seems to have some sort of material that is crumbling off... do i need to replace this material or what? Is this just scud thats been accumulated over time? It doesnt seam to be to me.
They are both the same size, if you have one bigger than the other one isn't cleaned yet. Material that is crumbling off is old rubber. Get your new seals and look at them and you'll understand which part of the seal is left there and it'll make more sense.
Check out the area I circled on this one. It’s crumbly in that area. I realize this sits under the seal. Also, the other BOSS is squeaky clean
You're gonna have to fully clean that to see what you have left. You can see where it turns from silver to black. Silver is boss black is old rubber. Clean it all up and see how bad it really is.
If the boss is busted/rotted it won't matter if it's only on the tip, as long as the surface where the seal contacts is in good shape you'll be fine, if not perfect a little RTV silicone will do the trick.
There's plenty of boss left for the knock sensor to screw into and sit on just fine so no worries there.
If the boss is busted/rotted it won't matter if it's only on the tip, as long as the surface where the seal contacts is in good shape you'll be fine, if not perfect a little RTV silicone will do the trick.
There's plenty of boss left for the knock sensor to screw into and sit on just fine so no worries there.
Gently and carefully start cleaning it, you have to regardless to see what you're going to end up working with, after it's all done it could come out better looking than you think, or worse, but you won't know until you're there. You could even start with lightly squeezing it with pliers, it may make the rubber crumble and get rid of a lot of the big chunks, or scrape/pick at it with a small screw driver or pick. Just go slow and easy and you may be able to save it if it's less than perfect.
