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Hello, I have a 1937 115 C 6 cylinder and need to remove the temperature gauge wire from the head. I have removed the square nut and the wire will not loosen from the head. What is the best way to remove without damaging it. Thank you in advance for any help with this request.

Here is what you are working with. Two places can cause issues. One is the bulb end where the tube connects seats against a smooth surface inside the head. Liquid seeping around that area getting between the nut and bulb can corrode and almost turn to concrete locking the bulb to the threads. The other is sediment which can accumulate around the bulb inside the head to expand and harden thus locking it in.

Some have had luck with ordinary rusty bolt removal products like PB Blaster and the like. Others have used something more toward the lime and calcium remover products like CLR. I have even heard that something like coca cola with lots of fizz action can break up the lock. Each requires time to soak and work and none are guaranteed.

Hopefully someone else will have a proven method but whatever you do, good luck. It is so easy to twist or pull the tube off the bulb.

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Thank you very much for the photo and explanation, I sprayed it with PB Blaster this past weekend and will keep at it since I know how it looks and your help. Many Thanks !!!

A trick with PB Blaster is to spray it on, then spray the threads with a blast of compressed air. It helps drive the fluid into the threads. I've used this trick a number of times and it really increases the ability of the stuff to loosen up the fastening.

Thank you David for this info and your reply, much appreciated !!!!

Should you need to consider an alternative to an oil based product, I used Evaporust to dissolve the rust and corrosion on my wire/nut. Fortunately, my problem was that the nut and wire were out of the block but fused together and I could soak the end in a cup of the stuff. Good luck.

April 2007 issue of Machinist Morkshop Magazine. They arranged a subjective test of all of the popular penetrants with the control being the torque required to remove the nut from a scientifically rusted environment.
Penetrant: Average Load:

none 516 ft lbs
WD40 238
PB Blaster 214
Liquid Wrench 127
Kano Kroil 106
ATF-Acetone mix 53.

ATF Acetone mixtures appears to work the best.

Thank you Mark.

Thank you for this formula, I'll give it a try.

Problem with acetone is that it takes all your paint off as well.