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MG TD TF 1500 - Inside diameter of Water Temp Capillary Tube

I have a doner water temperature guage from which I am going to graft the bulb to my existing guage. It still works a little but must have lost fluid over time. It's current full range of movement is a quarter of an inch.

The doner guage tube looks a good bit narrower than the original. I am wondering does this mean I could graft the two by inserting the narrower new tube into the old and soldering.

This would be simpler than sourcing a piece of capillary tubing to use as a 'sleeve' over the join.

The guage works a little now... so I don't want to cut it until I am ready to complete the repair. Getting a pieced of capillary tube to match may not be easy in Ireland.

So ... does anyone know the internal diameter of the original capillary tubing ? Or more simply is the capillary wall thin. If so I reckon with a little bit of jimmying I can get the new tube inside...


Thanks

Dave
Dave Moore

Dave-
The tube is quite thick, which is why they don't break unless abused. Sorry I cannot give you sizes.

FRM
FR Millmore

I had occasion to try to measure one when I repaired my water temperature gauge. The best I could do was to find that my .019" drill bit would just barely go in. There was a thread very recently about doing this. I put a few comments on the thread including an image of the sleeve that I used. Bud
Bud Krueger

ok... ao pretty narrow then - less than 0.5mm

Bud - what did you ask for when you sourced the sleeve ? I can't think it is the kind of thing a normal harware store will have here.

Was it from a specialist ?

Dave
Dave Moore

dave, a train or aircraft hobby shop should be able to supply you with the tube you need to use as a sleeve. regards, tom
tom peterson

Dave,

This site may help you see what is available; sourcing it there may be problematic.

On the left side of the page you can click on the ID you desire. Some is available is lengths as short as 1 foot. It takes a little searching.

Jim

http://www.mcmaster.com/#standard-metal-tubing/=lciqx9
J E Carroll

Dave, I bought it from a commercial source. Let me see what I can find. What is the o.d. of your donor tube? I'm assuming that you're repairing a TD/TF temperature gauge. Bud
Bud Krueger

I bought the tubing from http://www.onlinemetals.com/ . They sell small amounts at low costs. Now let me see what I bought, and if I might have some left over. Bud
Bud Krueger

Okay, Dave, I found my invoice from OnlineMetals. I bought a random-length (10" to 12") length of their Part # 4372 Brass Tube. Description: 0.125" (o.d), ).032" wall thickness, 0.061" i.d.. I still have about 8.5" left over. This size allowed me to slip the tube from the TD's gauge tubing into the brass tubing and tube of the donor gauge into the other end. Solder made up the difference. I'd be happy to send you some of this tubing if you'd like. Four inches worth would give you enough for a couple of goes at it. If your interested just send me your mailing address. My email address is shown above. Bud
Bud Krueger

As best I can measure without cutting off the protective wire coil...


Doner tube is 1.5mm ( .059 inches)

TF Original tube is 2.5mm ( .098 inches)

Presents me with the same probem you had Bud of two different diameters. Probably will have to drill out the internal diameter of half the sleeve.

The tube itself looks and feels pretty soft... Bud did you think to drill out or flare the original tubing rather than use a sleeve? Perhaps that + a little heat on insertion and a since the doner tube will be very cold it might just fit and seal as it contracts ?

On the other hand if you have a little of what you use left that would be a real help.

Dave
Dave Moore

You do not need to search the world for a "maybe". If you accurately measure the OD of your two tubes, get someone with a small lathe to make a short sleeve out of copper or brass, to size. If you are good, you can make one with a drill press.

Send me the numbers and I will make one for you, if necessary.

The donor tube will not be very cold at the splice, since you have to solder that. The bulb end will be cold, but you should splice as far from that as possible.

FRM
FR Millmore

You have mail Bud.

FRM - thanks for the offer. I should be able to work with the tube that Bud has.

I am going to be travelling mostly for the next few weeks. Once I have managed it I will let the list know.

Thanks.

Dave
Dave Moore

Dave, no email yet. budkrueger@comcast.net
Bud Krueger

Dave,

Be sure you are familiar with the working fluid in the bulb and how you plan to transplant the bulb. The liquid is described as an ether. I assume this is the commonly available diethyl ether. It is readily found in most chemical laboratories and is inexpensive.

Many of the common ethers are very volatile and highly flammable. To make things even more interesting, ethers have a relatively short shelf life under many conditions and degrade by forming peroxides. Peroxides are contact explosives, which means simply moving the container can cause them to detonate. I had a business associate who used to carefully take old ether containers to his farm and "dispose" of them using his rifle at a safe distance!

An unexperienced person may be able to work with diethyl ether without a problem and, likely, this has been done many times in the past. I am a chemist by training and it is important that I at least warn you of potential problems.

Please read more about working with diethyl ether, keep the bulb REALLY cold, and keep a fire extinguisher handy. Ideally, you want to limit oxygen from getting into the sealed system, but this requires more sophisticated techniques.

If anyone has questions about any of this, please let me know.

Larry
Larry Shoer

Thanks Larry. I had read some of the other posts about the volatile nature of the fluid.

Plan is ice/water and salt in a bucket. Make the cut with the longest length possible of the new tube left intact.

I am going to crip the end of the doner tube and cut off a couple of inches so I cab play with the play with the fit between old and new with the off cut.


Cut the old one ~ 2 feet from the intrument to give me enough to play with. Can#t help the little air that this will leave in the system...



Only make a second cut to open the donor tube at the last minute.

Gloves, safety glasses and respirator...


Hadn't thought of the fire extinguisher... but will have one to hand now.

:-)

Dave
Dave Moore

Dave, I'd suggest a 'dry-run' with the tubing to visualize where the splice is going to be before you make the cuts. Let me know if you want the tubing. To avoid wicking closing up the tube I'd suggest leaving at least 3/4 of an inch between the solder and the open end of the tubing. Ice water and salt worked fine for me. Don't worry about air in the tubing. Somebody's law from Physics class handles that. Don't forget to slip a piece of the spiral protective coil over the tubing before you do the soldering. Good luck. Bud
Bud Krueger

Dave,

I'm interested i your results. After reading this thread I pulled mine out of the box and tried it in some simmering water. Of course it's dead so I'll be going down the same road.

I think Bud posted his work sometime back so I'll check the archives.

Jim
J E Carroll

Dave, the small amount of ether in the bulb makes a respirator unnecessary. Diethyl ether is of little concern for toxicity. Approximately 100 years ago, diethyl ether was the first material used for general anesthesia during medical procedures. (It was also retired from this use because of its flammability!)

Bud, you are right that air will be displaced by evaporation of some of the ether from the bulb and its attached capillary tubing. My comment about oxygen getting into the system was more from the standpoint of the rest of the gauge assembly to which the bulb would be soldered. Ideally, the tubing and the gauge to which it is attached should be purged with nitrogen or even ether. If a person has access to ether (perhaps from a chemistry lab), a small amount of the liquid could be dribbled into the cooled assembly (cooled by placing the gauge and attached tubing in a sealed plastic bag in a refrigerator, not freezer). At room temperature, just before soldering, he ether will vaporize quickly and displace the air.

Certainly, commercial chemistry labs, university and college chemistry labs, and possibly even high school chemistry labs will have diethyl ether. You might see if you can link up with someone at one of these organizations and see if they can give you a sample bottle with 10-20 ml of ether. That will be more than enough for this project. The cost of bottle and ether is less than a dollar.

Gee, you guys have really caused me to dust off my lab skills!

Larry
Larry Shoer

Dave, just remembered one crucial thing that I almost forgot when I did mine --- Don't forget to slide the brass plumbing fitting over the tubing before you solder on the sleeve. You need to reinstall the one that matches the thread on your radiator (TD) or engine (TF). Bud
Bud Krueger

Bud - just sent my address again... odd...cut and paste the email.

Fingers crossed :-)

Dave
Dave Moore

Let me pour myself a wee drop of Paddy and put it by the computer to attract it. Bud
Bud Krueger

No sign of it, Dave. Try via my website, bud@ttalk.info
Bud
Bud Krueger

I tried with the new email...

If it doesn't work this time...

My email is Dave_Moore@utvininternet.com

Send a test to me I can then reply...

Thanks

Dave
Dave Moore

The bud@ttalk.info worked. If the power stays on, here in Massachusetts, I'll get the tubing in the mail. Bud
Bud Krueger

While waiting for the piece of tube generously donated by Bud I thought I'd have a go at repairing the old gauge before I snip off the bulb. Nothing to lose really.


Larry you were giving me some advice on the repair of my temperature gauge on the BBS. I have asked at a couple of chemists and drawn a series of responses varying from suspicion to bafflement ;-)

It occurred to me that I already have some diethyl ether though – in the bulb of the donor modern gauge.

Given the difficulties of handing this fluid what are my chances of getting it out ?

Chill it right down
Snip the capillary tube close to the bulb.
Extract with a syringe & needle
Inject into the original
Drop some solder on the top

Possible / worth a try ?

Too dodgy and recipe for unexpected loss of fingers?

Thanks

Dave
Dave Moore

See http://www.sunzeri.com/Stearman/tempgauge.htm for a paper about replacing the ether. I found it easier to replace the bulb. Bud
Bud Krueger

Dave,

It occurs to me that you may have been asking pharmacists (dispensers of medicine) for diethyl ether. My reference to "chemists" was to scientists trained in the field of chemistry. Any of these scientists will have heard of diethyl ether, although not likely the application in our cars.

You can extract the diethyl ether as you describe, but I am not sure this will be productive. I suspect the most common way our gauges stop working is when the ether evaporates through a tiny leak in the closed system. That means there may be no ether to extract.

The easiest way to temporarily store ether would be in a small glass bottle, if you have one available. It must have an air tight seal.

Cooling the ether will reduce the amount that is present as a gas, which is highly flammable. I would not try to solder, especially with a flame, near an open container of ether, whether cooled or at room temperature. Best to solder at the opposite end of a few feet of tubing.

Larry
Larry Shoer

So guys I had a go.

Since I was going to have to snip off the old tube while waiting for the sleeve from Bud I did this.

I then took a piece of the old tube and with a 1.5mm drill bit opened up the tube. I could do this successfully for about .5cm before the thin walls would break/I cut through.

I chilled the new bulb using the proscribed method.

I pinched the new tube and cut near the gauge. This way no ether could escape as I experimented. Even if it didn't work and I had to wait for the sleeve no harm done

The new tube was thin enough to fit inside the old. Tested soldering.

I did it a few times to get the feel then turned to the real thing.

Drilled out .5cm on the remaining piece of original tube attached to the old gauge. Made sure it was clear with a needle. Instered the clean cut end of the new tube and applied a blob of solder to the join

It worked first time!

Ok so I know that it should after all the advice but still I was suprised.


I was left with the fact that the needle now shot off the scale - I wasn't going to be that lucky ;-)

I had to open the gauge and lever off the indicator. I spend quite a bit of time fiddling with the position of the indicator.

Seem like the new set up has a higher range of movement/ is more temperature sensitive.

I set at 85 degrees with my kitchen meat themometer in the bowl of liquid the bulb is in. If I add more hot water / cool it swings futher than the meat themometer would suggest. I with just boiled water I can get it over the 110 mark and off the scale.

Any other suggestions on calibrating ?

I didn't have time to take her for a run - lost the light and couldn't quite get everything back together.

Either way I am delighted. I will perhaps live with it for a while and see if it settles down.

Now I am going to have dinner, a beer and watch a film (movie) with the family and a self-satisfied grin on my face.



Bud I will maybe have to use the sleeve if the join breaks ( won't be as strong as your method I think). Until then I will hold it in trust for the next person who wants to have a go :-)

Thanks guys for all your help.

Dave








Dave Moore

Dave, note that the low end of the scale is 30C. Your only real concern is the reading in the 100C area. I'd suggest putting the bulb into a pan of boiling water, relocate the needle at the 100C point and push it into place. If you're running a 50-50 mix of antifreeze you can see the gauge reading up in the oil pressure area. BTDT. You're doing great! Bud


Bud Krueger

I have been busy ( just qaulified as a diving instrucutor) and the weather has been rubbish so I only got a chance to get serious on this again this week.

I had calibrated using boiling water and popping the needle on pointing to 100 degrees.

Didn't work...needle stayed stubbornly reading 30 when running. I thought I had lost the fluid again.

Opened up the gauge and without the cover the needle swung back down quite a bit so I must have had some issues with the range of movement.

There was movement of the needle when the engine warmed up and the cover was off - so there was fluid


I calibrated by running the enging up to 'normal' operating temperature on a good run. Had the gauge removed from the dashboard on the floor at the time.

When happy I was nice a warm I popped the needle on at the half way / 85 degree mark.

Worked a treat. Responds quickly when started. Climbs to '85' and stays there. Pops a little higher when in traffic and left to idle.

Job done.

Great feeling of satisfaction :-)

Thanks everyone for all the help and encouragement.

Dave
Dave Moore

Dave, did the piece of tubing get to you? Bud
Bud Krueger

Reactivate
Kirk Trigg

Bud it did thanks. Apologies I never dropped a note to say so and thank you.

The good news is I haven't needed it ( yet ) as my weaker join has held up.

The gauge is working perfectly since the repair.

Dave
Dave Moore

Glad to hear that, Dave. Mine tends to show a bit of 'sticktion' at the low end. It abruptly jumps from 30 to 45 when warming up.
Other good news is that Paddy is once again available over here. Bud
Bud Krueger

Does anybody know of a shop or person who can do this professionally?

I have an almost identical problem with my PA temp gauge.

Gord Clark
Rockburn, Qué.
Gordon A Clark

This is the procedure on old aircraft and basically the same for old cars. PJ

http://www.sunzeri.com/Stearman/tempgauge.htm
Paul sr

i think i may try this over the winter. a really cold garage can't hurt...
was there a particular model temp gauge that you all used as a donor? getting one that works best could simplify the procedure.
i want to make sure it fits the threaded fitting and maybe works best on the tubing end.
TLW Wright

I think this was the one I used.

http://www.amazon.com/Sunpro-CP8217-StyleLine-Mechanical-Temperature/dp/B000FJQWXU/ref=sr_1_1?s=automotive&ie=UTF8&qid=1378391374&sr=1-1&keywords=water+temperature+gauge

Ignore the bit about for negative ground cars - it is just for the light.

This one has a long tube and comes with a set of adapters.

The tube is a lot thinner than the original which is why I was able to drill out the original and insert the new.

I saw the same one in Autozone when I was in the US last

Cheers
Dave
Dave Moore

Here is the best description of the process complete with pictures I found in my researches.

Cheers

Dave

http://www.ply33.com/Repair/tempgauge
Dave Moore

The Plymouth one was the one that I found most useful. Bud
Bud Krueger

This thread was discussed between 04/02/2013 and 05/09/2013

MG TD TF 1500 index

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