In Reply to: Re: 601 water temp gauge sending unit posted by Richard NY 2N on April 24, 2018 at 10:58:12:
Guess I'm thinking like the doctors do, give them the worst case scenario first, then the story can only get better. Brass fittings tend to get stuck. Going after them with any open-end tool will most likely just make things worse.
If you want to re-use the gauge. Try shooting the fittings with PB-Blaster. Wet them down, let them sit. Wet them again. Let them sit. Patience is a virtue. If you can just let the PB-Blaster work for a week or so, it may be able to work some magic in there. If this is the type connection I think it is, put a flare nut wrench on the big fitting in the block, and a smaller flare nut wrench on the gauge line fitting. Hold the larger wrench still, while trying to gently knock the smaller fitting loose. You may need three hands. Here's the encouragement! This works for me about 80% of the time. Fittings come apart relatively undamaged when I use the right tools.
For the other 20%, what I see too many times are fittings that have already been messed up. Someone tightened them with a standard open-end wrench, or (shudder) vice grips. In that case, I have already decided the gauge and fittings are going to be replaced. That is when I find a way to put a 6-point socket on it, so I get the whole thing out on the first try. I'm planning to toss everything and replace with new, but it's much easier if I can get the darn thing to unscrew in one piece.
Some of the gauge capillary tubes I've cut were filled with a gas. Not sure what that was. Probably inert, but don't sniff it. Older gauges may have mercury in them. I doubt momentary mercury exposure in the liquid form is a big deal. When I was in high school science class they handed liquid mercury out and we passed it around. Maybe that explains some of my shortcomings today? Vaporizing mercury with heat or spilling and letting it evaporate to be breathed is bad. Even worse if you heat those fittings and cause the capillary line to rupture. No way to control exposure when contents are spraying everywhere. They send hazmat teams out for mercury spills because it's long-term exposure that causes big problems.
Shopping the least-expensive gauge is where most people go wrong. Buy cheap tractor parts, you get cheap tractor parts, and all the problems that come with them. Darn, that wasn't very encouraging either. I'm not sure if Dennis Carpenter sells a "Just Like Original" gauge for that tractor. Better quality products that are made to fit that tractor should fit with no problems.