Retap the engine block?

[mikemcclain8]

Good morning, I'm hoping you can send me in the correct direction. I have a 2005 tige 22i with the marine power 340. It has a knock sensor on the port side and a plug on the Starboard side. The threads on the knock sensor side have stripped and I struggle to get just a little grip to hold the sensor in place. This season, it's barely in and I'm afraid it'll fall out mid use and then I'm screwed. I've read people say retap, but I've never done it and not sure you can retap an engine block.

Should I attempt it or take it in? If I retap, do I just find a knock sensor with the new size thread?

Thank you in advance.

Mike

[SurfinSnipes]

Are you sure it's not the knock sensor itself that the treads are stripped on? The knock sensor should be brass and the block is cast iron. I imagine it would be pretty tough to strip out a female pipe tap in a cast iron block with a brass male end, unless the block was severely rusted.

If the block is in fact stripped, I would start by "chasing" the block threads with with the original sized pipe tap. Then applying a few wraps of plumbers teflon tape to the brass knock sensor and seeing if that holds up.

If that doesn't work, I would see if you can swap sides that the knock sensor is on. Then put the plug on the "chased" thread side, with even more tape.

IF none of that works, swap the knock sensor sides. Then drill and pipe tap the stripped side to the next largest size, insert a new brass plug with thread tape. It will be easier to just buy a larger plug then buying a specialty knock sensor adapter.

I understand that a knock sensor may want a direct connection to the block as anything interfering with the threads could potentially dampen the "knock" the sensor receives, however thread tape should push out and make a seal while still making good contact with the block. A pipe thread should always have either pipe dope or thread tape on it. At least, in a plumbing application lol

[mikemcclain8]

I will try those options. I bought a new sensor this year and it won't thread either. It's been iffy in the past but always managed to get enough grab to function for the season. I'll try swapping sides. I thought about that but the sensor wire won't reach so I'll just add wire to reach the other side. Thanks for your help!

[lee]

You need an 1/4 NIP