1950s HELP LEAK from temperature sending unit

[Daffer]

My temperature sending unit behind the cylinder head is leaking coolant i tightened it but its still leaking just a little less now. How can I stop it!! My manual for my 1950 cadillac says not to add sealant to the threads. Please help thank you

[Big Fins]

Personally, I would put a beat of Loctite thread sealer on it. Not thread locker, but the white sealant.

Like the rest of us, things just sorta wear out.

["Cadillac Kid" Greg Surfas 15364]

What I have found is if tat sensor was not leaking and just started leaking it is the seal between the brass housing and the electrical sensor, meaning time to replace the sensor. The pipe threads on the Brass housing WILL seal if properly tightened
Greg Surfas

[Daffer]

What I have found is if tat sensor was not leaking and just started leaking it is the seal between the brass housing and the electrical sensor, meaning time to replace the sensor. The pipe threads on the Brass housing WILL seal if properly tightened
Greg Surfas

It's  brand new sensor but has a small leak at the bottom of the threads

[Jay Friedman]

I can't think of a sure solution, but maybe one of the following would work.

1. The sensor grounds into the threads of the cylinder head.  So if you could somehow put sealant on it in such a way that a portion of the threads on both the head and the sensor remain free of the sealant, it may work OK. 

2. Alternatively, you could wrap one end of a ground wire around the portion of the threads not screwed into the heads and attach the other end of the ground wire to one of the screws on the nearby firewall.  In this case you would have to be careful that the ground wire doesn't touch the hot wire going to the terminal on the sensor. 

[Daffer]

Ok so I'm hoping I got it sealed. I losseded the sending unit but didnt remove it then I used teflon tape and pushed it to the very end of the threads that stuck out then retightened. Truly I hope that's the only leak before starting my car. But as for now it seams like its OK. Thanks for the help!

[Jon S]

I was going to suggest Teflon tape on the threads. Good luck!

[Jeff Rosansky CLC #28373]

I've thought about replacing that on our 55, but it doesn't look like a fun place to get to.

[Lexi]

Agree with Jon, teflon tape it, but ensure the tape does not extend into the coolant passage way. Better yet, now is the time to install a mechanical heat sensor there, in place of the OEM unit.Mount the sensor gauge under your dash. That way, you can see exactly what temperature is happening under your hood. One of the few non-OEM change ups that I would recommend. Clay/Lexi