Leak at oil pressure sensor 16v 750

[Rich82GS750TZ]

This was my post a few weeks ago:

I should have known better than to comment on another member’s maintenance goofs. Changing oil and filter this evening, the red part of the oil pressure sensor spun when I tried to loosen the nut that holds the sensor wire terminal. Of course the 40 rear old terminal broke. Got it sorted. Went for a little night ride. I’ll have to keep an eye on that for oil leaks. The red part never spun before in previous removals of that screw.

Sure enough, today I noticed the puddle under where I had been parked.

Oil filter cover is all wet.

I removed just the top 2 acorn nuts and cap that covers the sensor. Sensor was wet too. So, I assume the red part that now spins is letting oil seep through. I was going to clean it up, spray it with foot powder spray, run it, verify the leaky spot. I should have, but didn’t.

I have a spare cover with intact sensor with red part that doesn’t spin. So removed spare from other cover and swapped it for the (presumed) leaky one. Both sensors seemed to have some sort of white shmutz on the fine threads of the sensor into the oil filter cover. I figured Teflon tape would do. It didn’t. A short ride revealed that the leak is still present.

So, the cart already before the horse, I decided to read what Mr. Clymer has to say on the matter of proper shmutz for the sensor threads.

Now, I don’t know what Bond No. 4 is or was, but what should I be using to seal the sensor threads into the oil filter cover? Something commonly available at an auto parts store would be good. What about plumbers pipe dope? Honestly, that’s what the old stuff looked like.

When I did the sensor swap, a bit of oil seeped out of the hole. That should have been my clue to stop what I was doing. I would image that hole wants to be good and dry before refitting the sensor with “whatever” on the threads. Later this week, I’ll get to fixing this. Will powder spray the area and definitively pinpoint the leak. Then refit the sensor. Maybe lift, tilt bike/engine rearward on the center stand a bit before unscrewing the sensor, drying, shmutzing and rescrewing it in.

Thoughts?

 

[1978GS750E]

I just replaced that sensor on a bike and I used pipe dope. No leaks!

 

[Rich82GS750TZ]

Thanks, Ron! Just wanted to be sure I wasn’t way off on this.

 

[Grimly]

Various pipe dopes would work. Just enough and no mo'.

 

[Rich82GS750TZ]

Thank's Dave. Will be sure to use "just enough". Is that like a pinch, a skosh, a smidgen, a modicum, or a tad?

 

[Rich82GS750TZ]

We’ll see if a shmear will do the trick.

 

[rphillips]

Ya'll forgot???... " a little dab will do ya"...... Also I've done gas piping for a lot of yrs. My opinion, Teflon tape applied clockwise, trimmed off at the very bottom edge so none can or will get inside.... No wrong answers, as long as some type sealer is used.

 

[dorkburger]

I've never been a fan of Teflon tape. First time I used it was on a fuel fitting on my car. A piece came off and got stuck in the needle / seat and caused a massive flooding issue. Installer error for sure, but personally the thought of an errant piece of Teflon in the engine oil would bother me a bit. But as noted, just enough is the correct answer.
In my years of hvac work Leak Lock is my go to thread sealer.

 

[Rich82GS750TZ]

When I removed the fitting with the teflon tape on it, ALL of the tape had pushed out to form a collar under the sensor on the outside of the oil filter cover. It was perfectly applied and yes I know which way to wind it. No way it could have worked. A short test ride last night and ride to work this morning look promising. But is was really foggy this morning and now it's raining. Wasn't supposed to rain, but it is. It usually does on the days I HAVE to take my bike to work. The MINI is being detailed. Something I treat it to once a year.

 

[rphillips]

Dang, I've never seen correctly installed Teflon tape crawl up the threads to the outer edge, for me that's the main advantage over pipe dope, as the liquid dope will be pushed to the outer edge. Also always trim the tape to the very inner thread, anything left below the last thread can't help seal anything, and has no place to go but inside what you're working on. Whatever works, just glad it's resolved.