Knock Sensor

david-b · #1 12-17-2006, 02:51 PM

Hey;
The threading on the block where the knock sensor goes in it stripped. So the knock sensor is in there, but more or less "wedged" in there tight since it won't tighten up all the way. When I get the head off in spring I'm going to try to re-tap it by hand, but until then, is there any damage that can happen? I've had it like that for some time now. Any problems or suggestions? Thanks.

blk_srt · #2 12-17-2006, 03:54 PM

I dont see how it would hurt anything.

crunchymilk55 · #3 12-17-2006, 04:24 PM

well it's just a microphone, so I don't the difference. But since it might rattle around it might trigger the sensor more. You will notice a significant power loss if it is sending voltage. Don't go WOT for a while if you want to be careful. You can't knock if you're not WOT or close.

david-b · #4 12-17-2006, 05:18 PM

But the way I see it is that since it's not all the way in there, that it may not be picking up knock. I've been at WOT quite often with no problems.

What would be the best way to "re-thread" it?

gthompson97 · #5 12-17-2006, 05:24 PM

The threads in the actual block are stripped? You're sure it's not the threads on the sensor it self? I'm not sure if those threads were cast in there, or done after the block was cast. Re-threading it might not be the best idea, cause you'll most likely get metal shavings inside the block. The only way I would do that is if it was a bare block sittin on an engine stand.

david-b · #6 12-17-2006, 05:30 PM

I got another knock sensor months back and it fit the same way. It's not the sensor itself, but the threads on the block. And no liquid or anything flows through where the knock sensor is at. I believe it's just a hollow chamber. So if I re-thread, then nothing will get inside to damage it. I can take compressed air and blow it out then.

I was thinking of drilling the hole just a little bit bigger and then forcing the sensor to fit in and lock-tight everything good. Bad idea?

gthompson97 · #7 12-17-2006, 06:02 PM

What do you mean drill it bigger and then force it to fit in? You should take a look at it the best you can, because if the threads are just damaged, you can fix those pretty easily, but if they're stripped or cross-threaded, then those are much harder to fix. If you drilled them out, then it would be way to big for the sensor and it would just fall right out, but I still can't see the block being stripped before the sensor....just doesn't make sense to me. I'll be home on tuesda so I can go out and look at my motor, it's out of the car so I'll just pull the knock sensor out and see if it's a chamber or hole or what it is, but IIRC, it's an actual hole.

david-b · #8 12-17-2006, 06:05 PM

It is a hole. But nothing flows through the there. I've had the car on without the knock sensor, and there's no leaks or anything. Nothing flows through there.

Long story short, the threads are stripped because I installed a T-fitting with the oil pressure sender unit a LONG time ago, before I knew that that was the knock sensor. I was young and stupid. I thought it was the oil pressure light, so I did the T-fitting and yeah, I don't know how after that bc it was so long ago, but it got stripped.

gthompson97 · #9 12-17-2006, 06:13 PM

Okay, are they stripped, or just damaged so it doesn't thread in right? If it's stripped, you should be able to thread it in and tighten for a year and it'll just keep spinning.

david-b · #10 12-17-2006, 06:20 PM

No, it won't go in straight. So it goes in sideways and wedges in pretty tight. It's half-assed

gthompson97 · #11 12-17-2006, 06:33 PM

I'm guessing they're somewhat cross-threaded then and may be able to be fixed without drilling. They make a thread fixer (don't remember the name) that is perfect for stuff like that. It's not a tap though, it doesn't cut new threads, it just *moves* them to the correct spot if that makes any senes if they aren't damaged real badly. We have some on the farm and they work wonders. I think they sell them at like napa and places like that, or home depot, lowes, etc, would probably have them too. Just make sure you get the CORRECT one or you'll be fucked for good. It looks close to a tap, but works a bit differently. If that fails, just run a tap in there straight and you should be good to go. Just make sure you don't wrench the shit out of it when putting the sensor in so you don't strip the threads for good. Loc-tite and nice and snug.

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