Help - Need Replacement Knock Sensor Bolt for '08 20V

[travis5550]

Well folks, I must have super human strength (or stupidity ), because I can't seem to quit over-torquing bolts and breaking the damn things. I was out draining the block on my '08 20V over the weekend before some cold weather came through, and I as I was putting the last half turn on the bolt that holds the knock sensor in, I managed to break it. Fortunately I was able to get it out easily, but I have no idea what to do about a replacement.

Has anyone experienced this before? Can I just hit up the hardware store and try to find a match, or is there something to the odd coating around the middle of the bolt? I've attached pics for reference. If there are any Tige dealers out there, please feel free to PM me. I'm also in the market for some replacement parts for my tower while I'm at it.

I really appreciate the help...got to get this thing running again so I can squeeze in a few more runs before breaking out the antifreeze.

Thanks!

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[boatwakes]

It's a flanged 3/8"-16 bolt and take the old one with you for length. Get a flanged grade 8 as a replacement, do not use a regular bolt and stop being such a meathead.

[travis5550]

haha thank you. do you think I can just grab it at the hardware or maybe an autoparts store, or is it something I need to find specifically meant for knock sensors?

[Wakeman22]

Would like to know about this too. The shop last year stripped mine and when I put it back in this year after winterizing it would not tighten.

[adamsjstt]

Would like to know about this too. The shop last year stripped mine and when I put it back in this year after winterizing it would not tighten.

I had the same thing happen and I heated up the knock sensor ( it seems to be solid brass) and filled the threaded hole, where the bolt goes, with solder while keeping it hot i threaded the bolt into the sensor, let it cool and unscrewed the bolt and now i have a brand new set of threads.

[Rossterman]

I had the same thing happen and I heated up the knock sensor ( it seems to be solid brass) and filled the threaded hole, where the bolt goes, with solder while keeping it hot i threaded the bolt into the sensor, let it cool and unscrewed the bolt and now i have a brand new set of threads.

Probably longer term solution would be to helicoil or threadsert so you have the original strength threads.

[boatwakes]

Actually want to revise my statement and say it's a flanged metric bolt with 8.8 strength rating, size M10 X 1.25pitch. However, there are no metric bolts on the standard american made small block chevy, unless you have an LS motor. SO...it looks like someone else has been there before you, replaced the bolt with the wrong one and now you have this. Can you update us and let us know if the 3/8" bolt I first recommended worked? I ask because that's the correct size for the accessory holes on those engines.

[CTravis911]

My mechanic told me one of my brass fittings is stripped out. Any idea what the part number would be? '07 22ve w/ 340 hp.
Thanks!

[Wakeman22]

My mechanic told me one of my brass fittings is stripped out. Any idea what the part number would be? '07 22ve w/ 340 hp.
Thanks!

I have this same problem on mine. I winterized it myself this year and found it to be spripped. Guess the shop did that last year and did not replace it and just left it that way.

[CTravis911]

Wakeman - I think the same thing happened to me.

Anyone know the part number of the brass fitting for the knock sensors? I don't have a shop close, so I was hoping to order online or over the phone.
Thanks!

[chpthril]

Wakeman - I think the same thing happened to me.

Anyone know the part number of the brass fitting for the knock sensors? I don't have a shop close, so I was hoping to order online or over the phone.
Thanks!

Are you looking for the actual knock sensor or a standard thread pipe plug? I think your 07 has a KS on each side of the block. IIRC, it bolt to a brass fitting that threads into the blocks drain port. Is that the brass fitting your seek? If so, how bad are the threads? Its pipe threads and soft, so they are somewhat forgiving and could possibly be cleaned up with a thread file.

[boatwakes]

The KS block fittings (on the lower part of the block, just above the oil pan) are 1/4" NPT or pipe thread. Mercruiser sells a fitting that utilizes a tee for the sensor and then a blue plastic wing nut with an o-ring for the drain but either way the block fitting is 1/4"NPT.

[Wakeman22]

chp, that is correct. It is the brass fitting on each side that the NS attaches to via a bolt. This brass fitting does not have a hole through it. I do not believe it is a 1/4"npt. I believe the threads inside the hole are stripped on mine and the bolt is kind of grey. This may be anti sieze on it. Just not sure. Options?

[CTravis911]

Are you looking for the actual knock sensor or a standard thread pipe plug? I think your 07 has a KS on each side of the block. IIRC, it bolt to a brass fitting that threads into the blocks drain port. Is that the brass fitting your seek? If so, how bad are the threads? Its pipe threads and soft, so they are somewhat forgiving and could possibly be cleaned up with a thread file.

To be honest, i haven't seen the threads. The mechanic that came out and winterized my boat told me they were stripped and that the brass fitting needed to be replaced. I plan on looking at it myself this weekend.
Thanks guys!

[CTravis911]

Does anyone know what size helicoil or insert would fit the brass fitting for the knock sensor bolt to thread into?
Thanks!