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

 

[normde2001]

Yanmar uses BSTP, (British Standard Tapered Pipe), threads.

 

[California]

deepNdirt, that capillary tube work just like a mercury thermometer. As temperature rises, the fluid expands and pushes the fluid inside toward the gauge, which pushes the needle up from zero. The tube can be microscopic.

As for the threads, I think the BST (British Standard Thread) is only on the oil pressure port down by the oil filter while the water temperature port has Metric threads.

I discovered that US pipe fittings interchange with BST with the exception that a few of my US fittings were too large to catch the first thread. The rest of them had sufficient taper to start and thread in several turns. A little Teflon tape is a good idea because one of the two has its threads cut deeper, even though the threads-per-inch is the same.

 

[Transit]

DeepNdirt, if you want/need the ultimate, consider a Digital Temperature gauge. Place the probe in the T-stat housing on the engine side of the T-stat. You will see when the T-stat opens and closes as the readings change.

 

[Travelover]

deepNdirt, that capillary tube work just like a mercury thermometer. As temperature rises, the fluid expands and pushes the fluid inside toward the gauge, which pushes the needle up from zero. The tube can be microscopic..............

Yea, sort of. Anyone remember an equation from a chemistry or physics class like PV=nRT? Basically the pressure is linked to the temperature in that bulb. So it really is a pressure gauge recalibrated to measure temperature.


Applet: Ideal Gas

 

[California]

DeepNdirt, if you want/need the ultimate, consider a Digital Temperature gauge. Place the probe in the T-stat housing on the engine side of the T-stat. You will see when the T-stat opens and closes as the readings change.

Oops. Paradigm mismatch. There's no thermostat.

That tractor was sold capable of putting out 17hp continuous at the pto without boiling over. If it no longer meets spec, I would put my attention into getting it back into compliance.

 

[Transit]

How about, {PV/T}1= {PV/T}2

 

[Transit]

Oops. Paradigm mismatch. There's no thermostat.

That tractor was sold capable of putting out 17hp continuous at the pto without boiling over. If it no longer meets spec, I would put my attention into getting it back into compliance.

No T-stat!! How then does the engine warm in the dead of winter?

 

[California]

Cardboard over the radiator.

These are rub-two-sticks together technology. Pliers and a screwdriver maintainable. Plus maybe a hammer. (That's from the owner's perspective. A lot of thought went into the design to make them so simple and reliable that there's simply nothing to fix for the first quarter century or so.)

 

[clemsonfor]

and a if i remember right a 10, 12 and someother mm size wrench. !6 or 18 maybe on some stuff, 14 maybe for draining fluids.

For the field, pliers and a screwdriver. You would need more pins for the one you loose than screwdrivers.

 

[deepNdirt]

Oops. Paradigm mismatch. There's no thermostat.

That tractor was sold capable of putting out 17hp continuous at the pto without boiling over. If it no longer meets spec, I would put my attention into getting it back into compliance.

The 1700 has never run hot with me as far as I know, when first getting the tractor I flush the engine cooling system/ radiator,along with draining and changing all fluids and filters, all has went well as far as the temps for the 1 year this month I have owned it, I never have trust the idiot lights is only reason for wanting to change to a temp gauge,
plus on Friday the wife and I went out to eat and drove her SUV and it ran hot due to a leaking seem in the plastic area of the radiator, luckily the SUV has a temp gauge allowing me to monitor the actual temperature while trying to get on back home, I pulled into the next station and got some water into it, and all was saved as far as the engine goes,.... so this kinda got me thinking again about my tractor and if ever it were to run hot? I do check all fluids including water/antifreeze mix before starting it up each time, although all it would take is one time the radiator to blow and run hot and I might be out of a tractor,..... BTW a radiator for the wife's suv cost 300 bucks which sounds High, but I look at it as the lesser cost compared to a new engine,:thumbsup: