Leak at threads of high temp alarm sensor

[JEC]

5.7 L Alpha I, Gen 2

Have small drip leak at the threads where the high temp alarm sensor screws into the thermostat housing.

I removed both the engine temp sensor (the one that feeds the dashboard temp guage) and the high temp alarm sensor while replacing a stuck thermostat. Had to remove thermostat housing and punch the thermostat out from behind and didn't want to jar sensors. While sensors were out I cleaned up the threads in the holes of the thermostat housing with a tap as there was rust built up in there. Boat is a 1991.

Replaced both sensors, ran boat on muffs, and there developed a small drip leak from the threads of the high temp alarm sensor. Tightened in increments with engine warm and it slowed down a fair amount but didn't stop. Don't want to screw this in any farther as it's in pretty far and in pretty tight now. Threads on this sensor look straight without a taper. Engine temp sensor looks tapered and it does not leak and didn't need to go in as far.

Tap had a taper, so could have expanded hole in housing slightly but no significant damage to threads in process and there's no leak at engine temp sensor with the same procedure done.

Thought I'd maybe leave it alone and see if it stops on its own or put some Perfect Seal or Rector Seal (pipe dope) on the outer threads (last few threads) of the high temp sensor and see if that fixes things and still retains the ground connection of the sensor to the t-stat housing.

Anyone have this kind of problem? If you did, what did you do or what thoughts do you have?

Thanks, JEC

 

[HT32BSX115]

Re: Leak at threads of high temp alarm sensor

Howdy,


I always use "pipe-dope" on the threads of my temp/oil/etc sensors. Get them tight enough and they'll always make a good connection. You can easily check them with an el-cheapo Radio Shack Ohm-meter if your worried about it.


Regards,


Rick

 

[DianneB]

Re: Leak at threads of high temp alarm sensor

The absolute BEST thread sealant on the market is "Master's With Metal". I have used it successfully on straight threads on steam boilers (360F) where nothing else would work.

 

[JEC]

Re: Leak at threads of high temp alarm sensor

Thanks for thoughts.

I used a small amount of Rector Seal ("pipe dope") on the male threads of the high temp alarm sensor (switch) and snugged it into the t-stat housing. Checked ground continuity with a volt-ohm meter and have excellent continuity, same zero ohm reading as when I check the engine temp sensor which on which no sealant was used.

Confident the Rector Seal will address the drip leak as I've never had a failure with Rector Seal. I'll check out Master's with Metal thread sealant if this doesn't work.

Appreciate the feedback.

JEC