VDO water temperature gauge - electrical or mechanical? [Archive]

Grizzly_Adams

7th March 2016, 01:22 AM

Hi Folks,

Would like to upgrade my water temperature gauge in the Defender (300tdi 110) to something that actually gives me a rough idea of the water temperature... I want to go with VDO but I'm confused but all the different options.

There's 'mechanical' or 'electrical' gauges which I gather is just the way the information gets to the gauge... is there a preference for which one to use?

Example Electrical gauge VDO 12V Electrical Temperature Gauge 40 120DEGC Sender | eBay (http://www.ebay.com.au/itm/VDO-12V-Electrical-Temperature-Gauge-40-120DegC-Sender-/331795760077?hash=item4d409183cd:g:KeIAAOSwqv9V6PW D)

Example Mechanical gauge VDO Water Temperature Gauge Mechanical 40 120?C Capillary Length 2600mm | eBay (http://www.ebay.com.au/itm/VDO-WATER-TEMPERATURE-GAUGE-mechanical-40-120-C-Capillary-Length-2600mm-/231765206419?hash=item35f6486593:g:9koAAOSwt6ZWVoS J)

Also some talk about Capillary lengths and others don't. Is that the length of the cable run from the sensor to the gauge for the mechanical gauges?

Too many options, brain overload.. Confused :eek:

Homestar

7th March 2016, 05:49 AM

Yes, mechanical gauges have a capillary that runs from the sensor to the gauge - this cannot be cut or extended - it is what it is, so if you end up going with a mechanical gauge then make sure you know where you're going to mount it and how long the capillary needs to be.

The advantages of a mechanical gauge is that you can just stick it in and go - no wiring needed (except the backlight if you want to see it at night). They read more accurately at the low end of the scale as they have a much larger deflection of the needle.

Electrical gauges will need a wire run from the sender to the gauge, as well as an ignition supply, an earth and again, the backlighting if you want to see it in the dark.

I've got both styles in different vehicles - both VDO - both are very accurate.

I don't really have a preference to be honest - they both do the job very well. :)

Aaron IIA

7th March 2016, 08:33 AM

Mechanical gauges either work or they don't. They are not prone to bad electrical connections or senders changing resistance with age. Although you must ensure that you don't kink or crush the capillary.

Aaron

cjc_td5

7th March 2016, 03:14 PM

I have been going through the same process recently.

A mechanical gauge capillary is simple and cheap but susceptible to kinking or puncture. The entire sender end (or gauge itself) must be passed through the hole in the bulkhead. The capillary is fixed length so must be coiled if too long or non-optimal route used if too short.

An electronic sender wire is easier to route but has more connections to go wrong.

I'm leaning towards an electronic gauge...

Chris

rick130

7th March 2016, 08:37 PM

I went mechanical VDO temp gauge as it means the thing isn't affected by the Defenders notoriously inconsistent earths, the reason the stock one has such a bad rep.

Blknight.aus

7th March 2016, 09:17 PM

youve nailed it.

I prefer mechanical capillary over the others on principle but VDO electrical for ease of installation/replacement.

Even though it generally takes longer to install the mechanical capillary due to the complexity of running the sensor and capillary I don't charge additional (if Im charging) for the time out of respect for the customers choice.

weeds

7th March 2016, 10:01 PM

Mechanical.....get the biggest span on the dial as you can, cannot remember what mine was, maybe 40 degrees at 7/8 o'clock and 120 degrees at 4 o'clock

schuy1

7th March 2016, 10:19 PM

Mechanical for the above reasons, but as said they are a pain to install in a modern car, need a large hole and the less wiring to rub on the better. electrical are quick and easy, small grommet in firewall for wiring, pretty strait forward wiring, I always run their own earth for reliability. If using a VDO the readings will be on a par with the capillary type, just make sure it is a genuwine VDO though and not an asian knockoff . Have been caught. The said variation in elec v capil. is really minor as there is no way you will wait until its in the red to pull over... right? Going up is going up, be it 2deg out or 10degr. If thats your worry fit an engine guard.
Cheers Scott

Pickles2

8th March 2016, 08:50 AM

cjc_td5

8th March 2016, 09:53 AM

Interesting discussion guys :BigThumb::BigThumb::BigThumb:

I was leaning towards an electric temperature gauge in my next install in my stage 1 v8, as I thought it was more "modern" than the mechanical type and so must be better. For sake of simplicity and accuracy, looks like I should not be discounting the old school, mechanical gauges after all......

Cheers,
Chris

Homestar

8th March 2016, 10:39 AM

"Guages"?...Anyone remember the Smiths guages,...beautiful stuff,...had 'em in a few of my cars in the "old days",..Amps, Oil, Temp, Perf (vac), & in my Austin Lancer, I removed the speedo binnacle & installed matching Smiths speedo & tacho (similar to MGB!).
I do remember the capillary type, I think many used the electronic one because it was easier, the capillary was a bit "bulky".
Pickles.

Yep, lovely gauges, I had a set in my old IIa. :)

All still available if you want to pay :) - Smiths (http://www.gauge-shop.com.au/catalogue/14-products-by-brand/105-smiths)

Pickles2

8th March 2016, 11:02 AM

Aaahhh, very good Homestar,...takes me back, they're a bit dearer now then when I last bought any.
I thought at one time that a few of these in our Puma would be good, but nowhere to put 'em really, & it'd look a bit "silly" I think!
Thanks, Pickles.

Homestar

8th March 2016, 11:33 AM

If the funds permit it when we start the fitout of Cam's Series 3, I'd like to do a custom dash using them.

Aaron IIA

8th March 2016, 01:46 PM

Check out Pricol gauges. They look a bit better than the bright colours offered by others.

http://www.redlineauto.com.au/s-110-pricol.aspx

Aaron

cjc_td5

8th March 2016, 07:33 PM

"Guages"?...Anyone remember the Smiths guages,...beautiful stuff,...had 'em in a few of my cars in the "old days",..Amps, Oil, Temp, Perf (vac), & in my Austin Lancer, I removed the speedo binnacle & installed matching Smiths speedo & tacho (similar to MGB!).
I do remember the capillary type, I think many used the electronic one because it was easier, the capillary was a bit "bulky".
Pickles.

I installed a smiths duo temp & oil pressure gauge in my 86" s1. Looked the part ☺☺.

Nothing like an old MG or Jag with a full dash of lovely smiths gauges.... ☺☺☺☺

Sent from my SM-G920I using AULRO mobile app

cjc_td5

10th March 2016, 01:33 AM

To continue the theme lads, what are your opinions on mechanical vs electric oil pressure gauges? Do the electric gauges suffer from the same potential earthing issues as temperature gauges?

Thanks,
Chris

Aaron IIA

10th March 2016, 08:25 AM

Same earthing issues with oil pressure gauges. Mechanical oil pressure gauges are a bit easier as their capillary can be cut or lengthened. You do have to get all fittings tight though, or you could get an oil leak at the gauge.

Aaron

cjc_td5

10th March 2016, 09:36 AM

Having filled a foot well up with oil in the past due to a loose connection, I am nervous about oil lines in the cabin.

Sent from my Nexus 7 using AULRO mobile app

gromit

10th March 2016, 06:03 PM

Some nice Smiths gauges here (including the water temp/oil pressure combo gauge).

Gauges for vintage & classic cars (http://www.holden.co.uk/displayAgroups.asp'sg=2&pgcode=070&sgName=Hardware&pgName=Gauges)

Colin

Mercguy

15th March 2016, 12:23 AM

Have used Pricol in the past >20 yrs ago. Neat, uncluttered, price was good and choice of mechanical or electric. I went with mechanical temp but electric oil pressure purely because of the copper capillary tube's propensity to be damaged easily.

Used auto meter sport comp and pro-comp liquid filled gauges, but they went with the car when I sold it some years ago. Not all they are cracked up to be, but very easy to read. quality is good, but you pay for it. I would use metric pro-comp gauges again if I had a car which the bezel didn't look out of place on.

Currently using VDO gauges in the boat and the aux gauges in the 16v are vdo 52mm. again, quality is there, and they are nice compact packages and very easy to read. natural backlight which suits my eyes. none of this LED backlit crap.

Pretty much get what you pay for these days. I happen to like the uncluttered VDO style. However....

There are a couple of things that really 'annoy' me. like requiring individual gauges when you want combined ones.

As much as I hate to say it, if you are completely flush with $$$$ then redarc make some absolutely top notch gauges, which are variable backit, LCD and easy to read. But they come at a price.
Possibly the most horrendous price for a 52mm gauge I've ever come across.
Made in Australia, but even auto-meter can't usurp them on price.

They have dual temp, dual combos /temp/pressure dual voltage etc... goes on and on.... best bit about this is you can get twice as much information in half the required space.
The only bitter pill is the price.

I would use them but I simply cannot justify those kind of costs, so I'll stick with my electric VDO gauges, which are just as good.

Aaron IIA

16th March 2016, 02:21 PM

I went with mechanical temp but electric oil pressure purely because of the copper capillary tube's propensity to be damaged easily.

Most pressure gauges now come with a nylon capillary, but even if you have copper, if can be replaced with nylon.

Aaron

cjc_td5

16th March 2016, 02:44 PM

Most pressure gauges now come with a nylon capillary, but even if you have copper, if can be replaced with nylon.

Aaron

I recently did a mechanical oil pressure gauge install using nylon tube. The nylon tube has a tendency to kink if not well routed which is a worry as it presumably weakens the tube and increases risk of rupture.

That said, I was replacing the tube as the previous copper tube had been torched due to the end of it once falling onto a live terminal at the starter solenoid, which immediately heated the oil inside so it ran out and ignited and burnt all manner of wiring nearby. It also shorted along the tube and caused all sorts of issues at the gauge binnacle!!! :(:( At least nylon tube will not do that!

Having fun.....
Chris

Zeros

20th December 2018, 06:21 AM

87County

20th December 2018, 06:38 AM

Hi Zeros, I can't comment on the Puma which would obviously have coolant sensors for operation. One of these locations may be the spot to use with a two way fitting, I will read what others advise with interest.

I don't think the tank would be a useful location. You need a reading from the coolant which is in the head.

Zeros

20th December 2018, 07:42 AM

Thanks, yes I assume it would be more a coolant loss sensor than temp in the expansion tank.

I’ll have a closer look at where the sensor might be on the head. Any advice much appreciated.

AK83

21st December 2018, 05:57 PM

....

Dumb question 2: What’s the consensus on the reliability of OBD port scan type guages - Engine Temp readings? Are these more reliable? Or are they reading from the same sensor as the original temp guage?

Dunno about reliability, but so far my experience with accuracy has been good, or excellent!
I've used cheapo OBD plugs for a few years now on various cars(couple of Japs, and recently a Peugeot(dads) and my own D2 V8 .. all been within a couple of degrees(using an IR temp gun).
Actually, the temp gun is the device most likely to give 'false readings' in a manner of speaking as the engine will have hot spots .. ie. some spots hotter than others.

The OBDII devices read the sensor readings that all go to the ECU.
The cars temp gauge also reads from the ECU .. not directly from the sensor.
So yes, in a manner of speaking, the OBD device reads the same info as the temp gauge.
But note that as has been claimed many times over that many temp gauges are dangerously inaccurate, and may show overheating after the overheating event .. it's not due to the sensor.
It'll be due to the way the temp gauge is set to display .. whether that means the temp gauge itself is slow to react, or the ECU is programmed to show temps that way.

And note that it's not just LR temp gauges that display this way.
Brother used to have a Patrol a few years back, and it blew it's hoses and overheated way after the temp gauge rose to the red mark too!

Zeros

21st December 2018, 06:23 PM

Dunno about reliability, but so far my experience with accuracy has been good, or excellent!
I've used cheapo OBD plugs for a few years now on various cars(couple of Japs, and recently a Peugeot(dads) and my own D2 V8 .. all been within a couple of degrees(using an IR temp gun).
Actually, the temp gun is the device most likely to give 'false readings' in a manner of speaking as the engine will have hot spots .. ie. some spots hotter than others.

The OBDII devices read the sensor readings that all go to the ECU.
The cars temp gauge also reads from the ECU .. not directly from the sensor.
So yes, in a manner of speaking, the OBD device reads the same info as the temp gauge.
But note that as has been claimed many times over that many temp gauges are dangerously inaccurate, and may show overheating after the overheating event .. it's not due to the sensor.
It'll be due to the way the temp gauge is set to display .. whether that means the temp gauge itself is slow to react, or the ECU is programmed to show temps that way.

And note that it's not just LR temp gauges that display this way.
Brother used to have a Patrol a few years back, and it blew it's hoses and overheated way after the temp gauge rose to the red mark too!

Thanks Arthur. [thumbsupbig] Reliability as in can you rely on them? and/or accuracy.

Ok so OBD devices should be better at reading the temp as read by the ECU. And you can watch the temp live, rather than rely on the flicker of a needle. ....So does that mean that an OBD guage temp reading would be just as reliable as a separately installed aftermarket temp guage?

Fubar

21st December 2018, 06:34 PM

I recently fitted a VDO mechanical water temp and had a few issues come up after the install. I installed mech VDO gauges where I could during the rebuild (oil,boost, water).

Almost straight away it would bounce around between 75-85 deg when you hit a bump. Outside of this temp range the needle is stable as you expect.

On longer journeys I had the needle climb to 115 deg relatively quickly whenever the truck was pointed up hill ( and at other time but less frequently), very worrying at first. But would immediately drop 2-4 deg when shut off and sometimes come back to 85 faster than it would be possible for the engine too cool down....if it was actually that hot, which it was not. It didn't feel hot and certainly didn't smell like a hot engine should.

It gave me grey hairs whilst away on a maiden voyage post rebuild (engine/gear box/full re-wire/new interior etc etc)...as soon as I could I got a heat gun on it I did and confirmed what I thought. The engine ran at 80-85 no matter what, every heat gun reading was just above 80 when the VDO guage read something above 100.

Given the limitations with the water temp gauge (once it's in that's it...good luck getting it out without damage) and the troubles I've had, I'm somewhat soured on the mech water unit in my 130 and will fit an electronic jobby shortly. This is a big thing for me as I am a big believer in keeping things non-electronic where possible ie I swapped out a Td5 for a 4BD1

Wallyb

21st December 2018, 09:16 PM

Reviving this very helpful discussion, thanks all. I’m looking at fitting a coolant temp gauge to the puma. Assume all of the above applies.

Dumb question 1: Where is the best location for the sensor itself? In the expansion tank?

Dumb question 2: What’s the consensus on the reliability of OBD port scan type guages - Engine Temp readings? Are these more reliable? Or are they reading from the same sensor as the original temp guage?

There is never a dumb question

I'll play devils advocate here - you already have a water temp gauge in the puma which should provide about the same response time as a second gauge so what is the problem you want to solve?

My direct responses...
1. I would not drill into the expansion tank.
a) it is plastic and bad mojo to tamper with it.
b) even if you replaced it with a metal version it is "away" from the main flow of water from the engine and would report a lower temperature than the main water flow.
c) so a secondary sensor should go somewhere around the radiator/water pump/engine block

2. Having a digital readout more precise.
a) This will make it easier to learn the nuances of the car ..eg sits at 85-87C pottering around the city. Can go up to 95C under load. etc etc ... so it helps you spot strange behaviour
b) most analogue meters have a very slow response time (just the way they work/part of the ruggedness)
c) some good commentary in the link below

Value of a Nanocom for 'Light' Work (https://www.aulro.com/afvb/90-110-130-defender-county/266840-value-nanocom-light-work.html)

Zeros

21st December 2018, 09:48 PM

There is never a dumb question

I'll play devils advocate here - you already have a water temp gauge in the puma which should provide about the same response time as a second gauge so what is the problem you want to solve?

My direct responses...
1. I would not drill into the expansion tank.
a) it is plastic and bad mojo to tamper with it.
b) even if you replaced it with a metal version it is "away" from the main flow of water from the engine and would report a lower temperature than the main water flow.
c) so a secondary sensor should go somewhere around the radiator/water pump/engine block

2. Having a digital readout more precise.
a) This will make it easier to learn the nuances of the car ..eg sits at 85-87C pottering around the city. Can go up to 95C under load. etc etc ... so it helps you spot strange behaviour
b) most analogue meters have a very slow response time (just the way they work/part of the ruggedness)
c) some good commentary in the link below

Value of a Nanocom for 'Light' Work (https://www.aulro.com/afvb/90-110-130-defender-county/266840-value-nanocom-light-work.html)

Thanks Wallyb. Yes that’s what I’m trying to work out. If you have an OBD reader monitoring engine temp idoes that mean no need to instal a guage?

AK83

21st December 2018, 11:46 PM

Back in the day(well, back in the day for me that is) I used to drive my dads old International C1300.
It had VDO gauges, and I remember the temp gauge used to be pretty quick responding.
Same with the oil pressure gauge too.
On hot days, it'd always respond quickly with temp changes climbing the Pentland Hills, a long climb up to Ballarat. Truck was always loaded over it's rated capacity for the Ballarat run, so of course that wouldn't have helped
Once on top of the climb tho, it'd settle back to 90-ish degrees.
I've never seen that in a VDO gauge again, and I liked it's more regular temp markings too.

But back on Zeros question .. I reckon it's always good to know actual temps.
Turn A/C on(assuming your Puma has A/C) in hot dry conditions and give it a hard time up a climb ... and you're sure to see a good temp rise from an OBD coolant display compared to what you'd normally see.

Just had a peek on ebay. translucent blue ELM327 bluetooth dongle less than $9 now! (I now feel ripped off, having spent $9.98 a few years ago [bigrolf])
Torque free is just that .. so it's not going to send you to the wall to give one a try.