Temp Gauge

[deepNdirt]

Hi all,
today I scored a Sunpro temperature gauge from an old truck at the salvage yard, my plans were to connect it up on my Yanmar, and do away with the idiot light, the Gauge is the kind that has the sending prob built onto the end with a solid copper wire inside a alumn shielding, and of course a wire and back-lighting bulb, before going through the trouble of hooking it up I am trying to test it with inserted the thermal sender in a pot of hot boiling water,
although the needle does not move I also tried holding a flame under it still no read, has this one simply burnt out? luckily I only paid 5.00 for it,
what type gauge have all of you used? I would like to buy what ever is necessary to do this conversion trouble free,
Thanks

 

[winston1]

Being honest, I don't know. I'm wondering tho if you need some voltage to actuate it. I'm thinking most temp gages don't register till the key is turned on. Just thinking out loud. Here is just a sample of many available at places like o'reillys. http://www.oreillyauto.com/site/c/d...=gauge+-+water+temperature&pt=N0527&ppt=C0134

 

[deepNdirt]

Not sure about the acc connection? there was nothing other then the red wire run into the fuse panel, and from the best I can make of it... the red wire would only feed voltage to the the bulb inside, there was also a ground wire to the side of the bulb housing, the thermal prob was connected to the T-state port of the 302 engine,

 

[ninefinger]

Your instinct is correct, that is a purely mechanical unit, no power needed. It would appear the tube is kinked or cracked thus making it useless. Just a thought, this is not an instant read unit, you will need to leave it in the water for a couple of minutes.

 

[ninefinger]

Do a search, an old thread started by pennwalk titled Adding guages to your Yanmar. Lots of good stuff there for you.

 

[deepNdirt]

O.K. Thanks :thumbsup:

 

[Travelover]

You can buy these bulb type of gauges pretty cheaply at HF or auto parts stores. For my Kubota B7100 I made a copper adapter (from a plumbing pipe connector) to insert in the top radiator hose with a brass fitting that accepts the bulb. Works great. Like you, I calibrated it in a pot of boiling water.

 

[rScotty]

In your picture that's not a wire connecting the sender to the gauge, it's a capillary tube filled with fluid. This is called a "mechanical" gauge to distinguish it from "electrical" gauges which have electrical senders, require power, and do have a wire connecting the gauge head to the sender. I like the mechanical type myself, but there is little difference. On yours the capillary tube may be cracked or crimped or squashed shut in which case the whole gauge setup is history. You can't replace just the sender or tube. But as ninefinger said there is a time lag before mechanical gauges give a reading. So give it a minute in the boiling water. If that doesn't work then the whole thing is no good. Mechanical gauges are either real good or not at all. BTW, if you come out of the block with a "T" fitting you can have the mechanical gauge and the idiot light both.
Your picture shows a type of sender fitting that will most likely require a thread adapter to fit the Yanmar block. Ordinary NPT threads are close, but not a true match. Yanmar's didn't use a standard US NPT thread or a metric thread in their motor blocks. They are different.
Cheap mechanical triplet gauge sets were about $30.00 at the discount auto store last I checked. And for that money it even came with a baggy of thread adapters among which was the rather oddball one needed to hook the temperature gauge to a Yanmar block. But you can't count on that.
good luck, rScotty

 

[deepNdirt]

Yes I test the sending probe for about a good 3-4 minutes in hot boiling water, is when I come to realize the gauge is most likely shot, I have just now held the shielding that wraps the copper tubing up to a light so that I could see through to the inside of the shielding while stretching it and looking through I found it is separated about 1/2 way down the line, so at least now I know why it is not working, I went ahead and and unwound the shielding around the broken area, I wanted to take a better look at what has been described as a tube rather than a wire... and it would take better eyes than I have to see a hole in the center of this tubing what it looks like is a solid copper ground wire from a 14 gauge romex :confused3:

 

[rScotty]

I wanted to take a better look at what has been described as a tube rather than a wire... and it would take better eyes than I have to see a hole in the center of this tubing what it looks like is a solid copper ground wire from a 14 gauge romex :confused3:

Yes, that is why they are called "capillary". The hole is very small. Trust us.
rScotty