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Mechanical or electrical temperature gauge??


reb78

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I'm looking to upgrade the coolant temperature guage on my 110. Racetech make a mechanical gauge (capillary) and an electrical one. Is one better than the other, or does it just come down to price and which sender unit fits the hole on the engine? The mechanical gauge is more aesthetically pleasing to my eye.

Links:

http://www.racetechd...les/Page768.htm

http://www.raceparts...instruments.asp

http://www.merlinmotorsport.co.uk/p17132/RACETECH-ELECTRIC-WATER-TEMPERATURE-GAUGE/product_info.html

http://www.merlinmotorsport.co.uk/p4172/RACETECH-WATER-TEMPERATURE-GAUGE/product_info.html

The VDO ones are nice, but these racetech ones are 1/2 to 1/3 the price (also, VDO dont do one with green backlighting to match the rest of my guages!)

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I've got a TIM capillary one which has proved itself to be very reliable and gives you a readout of the actual temperature, not just some random scale. I much prefer it to any electric gauge. You can even tell when the thermostat opens, as it drops a couple of degrees suddenly when the water starts to circulate through the rad.

Edited to add: the backlight is white, but I've bookmarked that link you posted t'other day so I can make it green to match the other gauges.

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Thanks Dave. Is the capillary tube fragile? (ive never seen one before). The mechanical guage is definately better to look at than the electrical one and the scale is more spread out thus easier to read.

Just need to determine what the thread and depth of the sender unit is now so i can order the right one (200tdi defender engine if anyone knows??)

Glad the other post was handy - it was bugging me that i had a milticoloured dash so i went on the search for the bulb covers!

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There's pros and cons to both types, it's an internet argument waiting to happen.

I like electrical gauges as wires are easier/more robust to handle & route than capillary tube, and no manufacturer has fitted a mechanical gauge to a car for decades, and they usually have good reasons for their decisions...

Fans of mechanical gauges would counter that mechanical ones give a direct measurement, with no sensor, no reliance on 12v supply, requiring zero wiring (unless you want to read it at night).

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There's pros and cons to both types, it's an internet argument waiting to happen.

Sorry. That wasnt my intention! :)

I have no experience of the mechanical guages, hence the question. Happy to hear both sides, but no arguing!

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my personal opinion is that when a mechanical gauge goes wrong, you get scalding hot water/oil where you dont want it.. But that doesnt happen with electrical gauges.

Richard, my 110 has a vdo temp gauge with a green back light, it also shows when the stat opens and theres a sender unit readily available for the defender 200.

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Richard, my 110 has a vdo temp gauge with a green back light, it also shows when the stat opens and theres a sender unit readily available for the defender 200.

Sounds interesting Dave. One of these?:

http://www.demon-tweeks.co.uk/Product.do?method=view&n=1771&p=16489&utm_source=Google&utm_medium=Base&utm_campaign=Gauges%20-%20Auxiliary

Mike - those were the ones i've seen you post before (i meant SPA in the original post, not VDO) - looks good, but big ££ (less than a knackered engine though). I do like the idea of the warning lamp though. Do you know how the backlight is set - are they LEDs or coloured bulbs?

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Is the capillary tube fragile?

Not really. It seems very flexible, but obviously you treat it with a bit of respect when fitting. Mine has been on there for about 7 years now with no issues. A friend also uses one on his comp safari racer with no probs, so they can take quite a pounding.

Re: thread size, the TIM one came with an adapter that seemed to do the job nicely. If not, your local plumbers merchant / pipe specialist will probably have something that will do the job.

my personal opinion is that when a mechanical gauge goes wrong, you get scalding hot water/oil where you dont want it.. But that doesnt happen with electrical gauges.

Not so with a capillary temperature gauge. It's basically a remodelled mercury thermometer, so the water only gets as far as it would do with an electric sender, from that point to the gauge is a thin fexible tube filled with mercury.

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You order the colour when you order the gauge. It's not changable.....

I ordered red. Shouldn't have done....As I couldn't get a red LED for my rev counter.

So. Green speedo. Bright blue rev counter. Red water temp gauge and green fuel gauge. Just like fairy lights....

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Playing devil's avocado: Why do you care about half-degree accuracy? All you really need to know is if it's too hot or not, and maybe if it's climbing or falling (so a gauge is nicer than a warning light on a switch). I don't care if my engine is "about 100 degrees" or "exactly 99.5 degrees", it's still too hot.

£5 buys you a temperature switch and big red LED, £10 buys you two so you have a "quite hot" and "very hot" warning light. Same is doable with an X-Eng fan switch.

For £178 I'd buy a laptop and USB data logger(s) and run a full digital dash & navigation setup in the car. And probably have £78 change...

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One thing about the 300Tdi that everybody knows is the very qyick ability to loosw water. Having a very accurate water temperature gauge with a coolant loss sensor should make you more aware of any coolant probles......

The thing is HOT.

In one country HOT = Deg C.

In otheres hot = 30Deg C....

I don't talk hot...Just in ambient temperatures......

When I bougt my temperature gauge a lap top was £600......

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I still can't see why you need 0.5deg resolution on your temp gauge when all that matters is whether the needle is on the "C" "N" or "H" ends of the gauge, a-la the Series dashboard.

Good luck finding an automotive sensor, or thermostat, that's actually accurate to better than ~10%. Your gauge just makes you believe you have a better handle on what your engine is doing, have you ever calibrated it against a proper standard?

https://en.wikipedia.org/wiki/Accuracy_and_precision

I'm happy with listening to my cooling fans - if they're on slow, it's normal, if they come on full speed I know things are getting hot, if they stay on full speed I stop and investigate. One day I'll wire up the warning light too.

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it's an internet argument waiting to happen.

It did...

I've had 2 capillary temperature gauges in my SIII...both failed inside 18months. I now have an electric version, which has so far lasted quite a while. It has at least allowed me to confirm that my disco temp sender in my TDi, is reading pretty damn accurate on the old Series temp gauge., rouhgly 90oC is the bottom of the N, and now that I know that, I don't worry about the independant gauge any more.

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I still can't see why you need 0.5deg resolution on your temp gauge when all that matters is whether the needle is on the "C" "N" or "H" ends of the gauge, a-la the Series dashboard.

Good luck finding an automotive sensor, or thermostat, that's actually accurate to better than ~10%. Your gauge just makes you believe you have a better handle on what your engine is doing, have you ever calibrated it against a proper standard?

https://en.wikipedia...y_and_precision

I'm happy with listening to my cooling fans - if they're on slow, it's normal, if they come on full speed I know things are getting hot, if they stay on full speed I stop and investigate. One day I'll wire up the warning light too.

Ah that's the thing. With the Land Rover temp gauge the actual water temperature could be 88Deg C or WITHOUT the needle moving it could be 100Deg C.

The thing that sold me the SPA gauge was the fact that they could actually tell me the thread size of the sender unit.....

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Sounds interesting Dave. One of these?:

http://www.demon-twe...20-%20Auxiliary

Mike - those were the ones i've seen you post before (i meant SPA in the original post, not VDO) - looks good, but big ££ (less than a knackered engine though). I do like the idea of the warning lamp though. Do you know how the backlight is set - are they LEDs or coloured bulbs?

Yes thats the one. You want a 5/8 UNF sender with it.

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Not so with a capillary temperature gauge. It's basically a remodelled mercury thermometer, so the water only gets as far as it would do with an electric sender, from that point to the gauge is a thin fexible tube filled with mercury.

Oh sure, because mercury is so much more pleasant to get on your face.

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One thing about the 300Tdi that everybody knows is the very qyick ability to loosw water. Having a very accurate water temperature gauge with a coolant loss sensor should make you more aware of any coolant probles......

The thing is HOT.

In one country HOT = Deg C.

In otheres hot = 30Deg C....

I don't talk hot...Just in ambient temperatures......

When I bougt my temperature gauge a lap top was £600......

I have read that the main problem with a 300 is that the sensor sits about 4" lower than the highest point in the cooling system. That is a problem I would look at first myself, rather than spend good dosh on something to replace something that actually works quite well.

As fridge says in the red is no good, the rest is just background info, causing you to have your attention somewhere else than on the road.

daan

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Oh sure, because mercury is so much more pleasant to get on your face.

Forget to engage your brain before typing? There is only a very minimal amount of mercury in a capillary gauge (they are only £25 after all) and it's never under any pressure (other than the resistance needed to move the needle), so why would it ever have any reason to explode and end up on your face?

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What works well Daan ? A temperature gauge that reads in apples. Also a temperature gauge needle that doesn't move in a 10 Deg C rise in temperature ?

Please read what I wrote earlier.

" " Ah that's the thing. With the Land Rover temp gauge the actual water temperature could be 88Deg C or WITHOUT the needle moving it could be 100Deg C. " "

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If your not desperate to have a round gauge, what about industrial stuff http://www.sensormetrix.co.uk/product.php?id=396 with data logger? There are some cheap displays about, but I can't find my catalogue.

But I went with capilary off a Fergie tractor, for an instant glance read-out in green or red on both landys. I took the white-on-black with F and C out as unreadable without staring :glare:

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