External Thermostat Removal

[Steam Driver]

I know this has been discussed a lot before; I looked it up. But I thought I would post what worked for me in case it could help someone else.

I have been soaking the oil line nuts with PB blaster and Kroil for several weeks now; I think that is a key. However even with that, and heat, I was having no luck with the regular 36mm oil line wrench as sold by our host and others.

Analyzing it I decided there were a couple of problems. First the 36mm open end wrench is too "fat," i.e. too much material on the sides. It doesn't really fit in the space available well. Plus the tapered handle offers no real place for a pull-pipe (push-pipe in this case). Finally the open end design means that in addition to applying torque you also need to concentrate on keeping the wrench square on the nut.

Second, there is no really good way to counter hold the assembly to keep it from rotating as you try to unscrew the nut. So I attacked it from the tool angle.

For the 36mm nuts I got a 36mm crowsfoot, 1/2-inch drive. I found an excellent one on line by Martin Tool. It is like a short socket with the side cut out of it, almost like a tubing wrench. It is about 3/4-inch deep and once on the nut wants to stay there. So the wrench alignment factor is gone.

The counter holding stymied me for awhile and then one day walking through the local Ace I found what I needed; a small hickory hammer handle replacement. Inserted into one of the thermostat inlets so the long axis of the oval part where the head goes is parallel to the applied torque the handle jams against the body and applies the needed counterforce, so you can concentrate on just pushing on the wrench. And since the hickory wood is softer than the aluminum housing it doesn't damage that, either. No distortion, no marks.

Using this technique the inner line nut came off easily with just the crowsfoot, breaker bar, and no heat. But when I tried it on the outer one it didn't work, at first, even with heat. The next evening, having acquired a 24-inch push-pipe, I was able to break the other side loose, with no heat. No damage to the thermostat threads in either case.

So, there you go. Worked for me. The Martin crowsfoot is a quality item, about as good as Snap-On or Cobalt as far as fit and finish goes. There are a lot of crowfeet out there, you just have to get the one with the least width across the wrench.