Case temperature gauge conversion

[dc in illinois]

This message is for Joe (wa)
Joe in earlier posts you had mentioned converting tempature gauges on 300/350 to
Electronic gauges using original sw face plate to make look original and work like it should . I'm in need of knowledge as to how to go about that I am working on a 300/312 tractor as we speak thanks for any help or advice you can give

Bob

 

[kenbob]

If it is only the temp gauge not working, there are several you tube videos on how to repair your original by repairing your leaky line. I did mine and it cost about $30. If you want to go that route I can give you step by step on how I did it.

 

[olgentdc]

Are You telling of repairing the mercury sending line ? Wow , I want to see that ?

 

[kenbob]

It is pretty simple. first cut the old line off, but leave at least 4 or 5 near the gauge. blow a little compressed air in the gauge line to make sure the needle moves. If so countinue.
Buy two cheap generic temp gauges. Buy 2 with rubber coating. I only say this is the one I bought with a wire coil around it was too flimsy. The guages out of the parts seller Rock Valley Ia have a sufficent copper line. One gauge is used only to size your splice. Cut the tube. Find The right size copper tubing to splice between the donor gauge and the Case gauge. They are not the same size. As I remember i found a piece to slide on the donor and then had to ream the other end out with a small drill to get it to fit the Case side. Once you have that splice of copper fitting nice, you can discard all of the old gauge. Solder the splice to the Case side tubing.

Here is where it gets fun. Take the other gauge and let the bulb end sit in either dry ice, or a salted ice brine (we used brine) for at least an hour or longer if you want. Then decide how much of that line you need to attach to the Case line. Very gently cut that line with a tubing cutter (you don't want to mash it), and quickly insert the line into the splice. Make sure you can see the tube is open and not smashed shut. Solder that line in to the other side of the splice with an iron (Not a torch!). That's it. I got mine right on the first try. After installed the gauge seemed to be right on on temp. Maybe I was lucky. The point for the unaware is the gauge operates by volitile gas. The chilling the bulb keeps it condensed in the bulb for a short while. I would guess if you don't do it fast enough some gas will seep out. As I said there are several u-tubes on it, but these instructions are how I got my Case 351 gauge to work.

 

[kenbob]

I should have filmed the job but forgot my phone.

 

[kenbob]

If you have a very precise micrometer, you wouldn't have to buy a throw away gauge. We didn't. Those gauges were about $15 each I think.

 

[cskent]

this is interesting, i solder these capilary tubes doing hvac repairs I use a good triangle file to cut them working carefully all the way around the hollow tube a tubing cutter will smash the hollow if not real careful then braze, or solder the coupling on id like to see the results of a working gauge.

 

[kenbob]

Correct. I sold my tractor with that gauge, but I have a dash for a 311 I might be doing over winter. All I can say is Case gauges arent degreed, so I can't tell how exact it ran, but it was always to the left of straight up, once warmed up. THe you tubes out there are for car gauges but it is the same thing. If I do another I will try to do a video. That gas is so volatile it doesn't even his when you cut the tube if you have that bulb in a cold slurry. It hangs in the bulb until excited by heat.

 

[Tgrasher]

The heat gauge has a narrow sweep so I took the face plate off and took it to auto parts stores till I found one that matched the sweep. Carefully cut the casing off the new one, made a new mounting plate and put the Case face plate on.

 

[kenbob]

Here is a video of a repair. https://www.youtube.com/watch?v=isaCE7Jm3Z0