Lotus Elan

Ambient temperature gauge

PostPost by: mikealdren » Wed Oct 31, 2007 8:10 am

I heard a variety of views on these:

Some say that they are a waste of time and cannot be repaired.

Others say that they can be refurbished but (for unexplained reasons) it doesn't always work.

I've also been told that the gas used is dangerous (wonder what it is).

Has anyone had one repaired/refurbished?

I suspect there's also a good market for an upgrade to fit a modern gauge with a remote electric sensor into a period gauge. Anyone tried it?

regards
Mike
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PostPost by: pmallinson » Wed Oct 31, 2007 9:06 am

Mike

The gauge, Capillary and Bulb are what's know as a vapour pressure system (I'm a time served instrument tech many years ago ! :shock: )

Basically it works on the fact that all liquids give off some gasses and dependent on the temperature they are at give off more (increasing temp) or less (decreasing temp) so using this phenomenon a pressure gauge connected by a thin pipe (the capillary) to a vessel (the bulb) full of a liquid will monitor the pressure of the gas above that liquid and then we mark the scale in temperature as it equates to the gas give off at a certain temperature !! :shock: (that was 30 years ago in tech )

I'm not certain but nearly sure that the ones on the Elan being the temperature range they are will be full of some sort of alcohol so not particularly dangerous (unless you wanted to try and drink it !)

So That's how the originals work or not if the gas has been allowed to escape through a hole in the system which is the case for 99% of failures.

As for fixing them there are a few people who say they will mentioned in previous threads but JDO Inst Eng's
[url]http://www.jdo1.com/page8.html[url]
may be worth contacting as well as Speedograph Richfield Ltd
[url]http://www.speedograph-richfield.com[url]

As for making an electronic one it would be fairly easy using a thermistor circuit and you could even have a warning light for frost !! :D

cheers
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PostPost by: Robbie693 » Wed Oct 31, 2007 9:44 am

you could even have a warning light for frost !!


Now that's a cool idea! (forgive pun)

I have a video with Paul Matty on giving technical advice and on it he mentioned that they can be fixed, but didn't give any clues how or where it could be done...
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PostPost by: DrEntropy » Wed Oct 31, 2007 11:09 am

Not sure about the ambient temp gauge 'filling' but there's an article floating about over here inna colonies wherein a guy uses an aftermarket ether bulb gauge to 'patch' a Smiths dual engine temp/oil pressure one... Dry ice to condense the ether in the new unit's bulb, cuts the capillary tubes close (1 or2 inches ) to the gauge and solders (NO open flame!) the old and new together with a copper sleeve. No idea if this really works but no reason it shouldn't, "in theory". If the ambient temp bulb material could be identified the "patch" could be similar.
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PostPost by: Elanintheforest » Wed Oct 31, 2007 11:11 am

The ?how? is quite straightforward?I repaired my S3 water temperature gauge which is similar to the ambient gauge.

At the end of the bulb is a blob of solder?unsolder it and a small hole is revealed. I had a bottle of ether which I put in the freezer for a few hours. Then warmed up the bulb with a blowtorch, plunged it into the cold ether, and the fluid was sucked inside. Then quickly re-solder the hole and ?.it worked. Tested it in boiling water and in ice, and it?s pretty accurate, and still is 30 years on.

And the whole process gives you a nice, warm glow inside?almost euphoric. That may have been the ether though, which I doubt you can buy today, and I?m sure that the heath and safety enthusiasts may declare my approach as being a little risky.
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PostPost by: DrEntropy » Wed Oct 31, 2007 11:35 am

Geez, Mark... we were posting at the same time, apparently. Essentially the same "fix". The aftermarket gauge purchase would negate the need for hunting down a supply of ether. As a dodge I think aerosol "starting fluid" is ether. P'raps stuffing a can of that in dry ice then puncturing the can.... err.... nevermind. :shock:
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PostPost by: Frank Howard » Wed Oct 31, 2007 11:42 am

Mark,

Great story. I have a question though. Wouldn't the quantity of ether have an influence on the accuracy of the gauge? I mean if you put in 1 ounce of ether, wouldn't you get different temperature readings than if you put in 3 ounces?

How did you know how much to put in? I realize your gauge is accurate, but did you measure the amount of ether or did you just luck out?
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PostPost by: Elanintheforest » Wed Oct 31, 2007 1:08 pm

It was pure luck that it was the right amount, it didn't explode and that I didn't pass out doing it! I repaired a couple of petrol tanks on Elans until my luck did run out....I'll only buy a new one now, and I won't be repairing any gauges either. How age (and/or experience) wrecks the adventurous nature of youth :shock:
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PostPost by: pmallinson » Wed Oct 31, 2007 1:37 pm

Frank Howard wrote:Mark,

Great story. I have a question though. Wouldn't the quantity of ether have an influence on the accuracy of the gauge? I mean if you put in 1 ounce of ether, wouldn't you get different temperature readings than if you put in 3 ounces?

How did you know how much to put in? I realize your gauge is accurate, but did you measure the amount of ether or did you just luck out?


So long as the amount of liquid was enough for it all to turn to gas at the highest operating temperature /pressure then it matters little how much liquid is in.

Rather too much than not enough otherwise it would work for so far as the liquid gasified then stop when it was all gas as there would be no more to expand and increase the pressure.

The problem with trying this yourself in the first place is you have to know where the leak is that you lost the gas / liquid through in the first place, the the real possibility of doing yourself serious harm also negates the job to an amature really.

Cheers

Peter M
Last edited by pmallinson on Thu Nov 01, 2007 6:14 am, edited 1 time in total.
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PostPost by: JJDraper » Wed Oct 31, 2007 5:24 pm

I have spoken to the guys at Speedograph (www.speedograph-richfield.com/) and they say they can repair/refurbish this gauge for 70GBP inclusive of VAT & carriage. The gas is Ether (sends you to sleep and is carcinogenic) but they seem to be happy to recharge the units. I asked if he was interested in a manufacturing a batch of instruments converted to electronic operation, but he did not seem enthusiastic - pity.

Personally, I think the guage is too fragile for its purpose, as the capillary length invites damage through both mechanical crushing and fatigue. If anyone succesfully converts one of these to electronic operation I think there will be a well trodden path to their door!

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PostPost by: pmallinson » Thu Nov 01, 2007 4:00 am

Quote "If anyone successfully converts one of these to electronic operation I think there will be a well trodden path to their door! "

Count me out as I have enough on my plate what with hub extractor, window channels and dash transfers, especially the latter and all the changes !! :shock: :D

But someone else could take this on as a wee project I'm sure especially if they could get gauges made with the right scale from someone like
http://www.minipressuregauge.co.uk/ now there's a start for you :D :wink:

Thermistors dead easy from Radio Spares etc :wink: go on have a go :!: :!:


The idea of the frost warning light could probably be negated as you would possibly have frost on the inside of your windscreen anyway and possibly the wife winging and moaning about the heater not working again giving a fairly clear indication of it being cold :D :roll:

cheers
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PostPost by: Gordon Sauer » Thu Nov 01, 2007 4:33 am

In US had mine done at Palo Alto Speedometer (CA), was about $200 several years ago, including complete refurbish with bezel renewed and all--capillary tube had just been cut off so new tube attached and bulb and ether charge. I live in Texas--not sure if it reads blackice or not! Gordon Sauer
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PostPost by: robcall » Thu Nov 01, 2007 4:34 am

The Lotus Excel has an LED ice detector instead of an ambient temp gauge.Not sure of parts availability or indeed the look of an 80's item in a 60's car.
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PostPost by: c.d.s. » Thu Nov 01, 2007 6:02 am

You can still get ether from artcraft chemicals as its still used by wet plate
photographers.

They are a bit of a mad/entertaining lot due to the use of such chemicals 8)


regards

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PostPost by: Frank Howard » Thu Nov 01, 2007 12:34 pm

As I have a left hand steering car, a few years ago, I had http://www.nisonger.com/shorten the 8' tube to 3' and there was still enough left to "coil". Of course, they also rebuilt the combo gauge. Total cost was $120US.
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