Temperature gauge lineariser

[Elanlover]

Blair, you do have an Elan don't you? The eternal problem has been that the gauge and sender are not matched so normal running is a needle width under the ¼ mark which makes it difficult to see when e.g. the thermostat sticks open because the gauge only drops to two needle widths below ¼.

Look at the ElanScan plots above and you can see that the thermostat keeps the temperature at ~80-85°C. In the absence of sufficient airflow, the temperature climbs to ~110°C where the fans kick in and drop the temperature to ~100°C. My plan is to activate the fans at ~95°C to keep the maximum temperature cycling around 90-95°C similar to the Dickman low temperature switch. Note if my box fails to operate correctly or if it is removed, the fan switch will still operate at 110°C.

Interesting that while I'm aware that the gauge seems to run alarmingly high I never seem to get the car to run for any length of time at the 1/4 mark. it always seems to run at near the halfway mark for me then quickly runs up to the 3/4 mark if I stop at a light (only seems to take about 60 seconds on a hot day).

Regardless, I'm in.


1. Geoff
2. Pinky
3. Rob P
4. Fredjohn
5. Enright
6. Enright
7. Jeemy
8. KevB
9. Cliff
10.Jim (muley)
11. David Griffiths
12. rip
13. Elanlover

[steve matthews]

The Rodney Dickman lower temp, sender unit works fine, and is an excellent upgrade.
The function I would like to incorporate is the electric water pump on when car turned off.
I do not want to wait for the temp, to trigger the electric pump but rather it automatically comply.

This pump will cycle on and off after a vigorous track run in the paddock. Why not just
a good timed run to cool down the turbo and engine.

Can this rubber band box idea have a programmable setting for temp. and electric cooling pump
Or am I asking too much.

Steve - wanting a cooler turbo

[GeoffSmith]

Prototype road tested but needs some minor adjustment to the correction factors as it sits just above halfway.

It will take some getting used to, as you glance at the instruments and panic because you're at half scale.

[GeoffSmith]

Well that went well. First serious run comparing the gauge to ElanScan data (over BlueTooth of course) shows I'm only a few degrees out across the range....

Img_0092x640.jpg

Img_0095x640+.jpg

Img_0093x640.jpg

And in response to the likely questions: Wha'd'ya mean? Doesn't your ElanScan do that?

[Elanlover]

And in response to the likely questions: Wha'd'ya mean? Doesn't your ElanScan do that?

Grrrrr.................

[HJ2]

If your tooth is really that blue, why not brush your teeth Geoff...
Or better yet: I want a Bluetooth Elanscan as well!

[CalElan]

came across this thread while looking at how to test the electric pump. This sounds like a cool mod...<--- see what I did there?
Did it ever end up as something we could buy or are there any instructions on how to make one?

Thanks...

[Doug]

cue the Fiddler

[Elanlover]

For the record, I am willing to pay real money for this - not that monopoly money I used last group buy. Or possibly a golden nectar substitute for said money.

[CalElan]

What he said ^^^^^^

[Cool Runnings]

I must say I'd be keen on this mod as well. Any news?

[Tuga2112]

Geoff,

What kind of temperatures are you aiming to be at when the needle is at the 1/4, 1/2 and 3/4 ?

As things stand in my car i get a bit twitchy when the needle goes over 1/2 as my thermostat is a bit moody, sometimes the fans kick in soon after the 1/2 mark, other times the needle needs to get to the 3/4 before the fans kick in.

I been thinking of making the manual override that martin has, but instead of controlling it via the ingition, i rather use a switch in the dash.

[Elanlover]

Geoff,

What kind of temperatures are you aiming to be at when the needle is at the 1/4, 1/2 and 3/4 ? ............

All these answers are in this thread. The first post even

[lotusflasherman]

Interesting thread. Hadn't seen it before so did a bit of testing myself, as I had a warm engine after mucking around with my Boost Gauge... but first a few comments:-

When I was at college (almost 5 decades ago!) I attended a Thermodynamics lecture that was supposed to be about steam turbines for electricity generation and the lecturer, who was a crazy guy like Doc Brown from Back to the Future, threw in the comment 'Laws of Thermodynamics say car engines work best at 108C, but that's above boiling point so that's why they have a pressure cap which you should never remove if the engines hot' - and then carried on about steam turbines. Nobody ever questioned that, because if you did you wouldn't understand the answer anyway, but most of us remembered the number as Radio Luxembourg broadcast on 108m Medium Wave (showing my age here!). Have since found it several times and engines should run at something just above 100C in the cylinder head.

The Mini Cooper originally came with a 95C thermostat that weren't easy to find but if you replaced it with a lesser value the oil in the rocker box would get condensation and cover the rockers in a creamy 'goo'... never knew why but it did!

Elan Service Notes Electrical Page 4 says "Under normal running conditions,the gauge needle will stay around the quarter scale mark, with fluctuations occurring as the operating conditions change. During periods of idling, or in heavy traffic, the needle will rise to just over the three quarters mark before the cooling fans cut in. If however the gauge needle rises well into the top quarter of the scale for more than a few minutes, the engine is in danger of overheating, and driving style should be modified accordingly. If the temperature remains at this level, a problem is indicated and the engine should be stopped and the cause diagnosed and rectified."

OK then, very useful info' but the problem with this, and the gauge, is they don't give us any numbers to know what we are actually looking at.

I've observed that my Elans usually run at 1/4 scale in UK but in the south of France with ambient around 30C they run closer to 1/2 scale. They only go above that when in traffic and the fans kick in around the 3/4 mark but it can creep marginally past that, due to latent heat in the system, until the needle starts falling again.

I have a digital temp gauge with a transducer on the end of a wire so I put this against the thermostat casting and wrapped it in pipe lagging to hold it in place and give an accurate reading.

Normal running for me is at 1/4 scale but when idling on my drive the needle quickly climbs to 1/2 scale and settles there for quite a while. After quite a while it then starts to climb slowly until the fans kick at the 3/4 line that I've now found is around 100 C. Actually 100.2C as shown here...

100C.JPG

Do need to be aware of 'parallax' - the error by looking at a needle from an angle. ( Scientific (analogue) instruments have a mirror across the scale so you can check you are looking straight down on the needle)...
Viewed from the driver's seat it looked like this

fans on.JPG

So this looks more like the "3/4 mark when the fans cut in" from the manual, so it looks like my car seems to behave just as the manual describes, so I won't be doing anything.

I'd also point out that both the temperature gauge and petrol gauge are supplied from a 10V +or- 0.1V stabilizer unit in the back of the instrument panel, to allow for whether supplied from battery (around 12V) or charging alternator (could be 14.8V) so if you are checking yours DO NOT supply from a 12V battery or you'll get a false reading.

[epipete]

........ so I won't be doing anything.

Which is all very interesting and useful, and mine works this way most of the time as well, nevertheless, it still takes nerves of steel to sit in a traffic jam begging the car in front to move as the needles commences the March of death up the dial face!

I'd like one of these pleeeeze!!!!

Pete

[lotusflasherman]

........ so I won't be doing anything.

Which is all very interesting and useful, and mine works this way most of the time as well, nevertheless, it still takes nerves of steel to sit in a traffic jam begging the car in front to move as the needles commences the March of death up the dial face!

I'd like one of these pleeeeze!!!!

Pete

but if you don't know the actual temperature how is it 'the march of death' ? As long as the fan kicks in and you don't hear any 'hubble bubble' or steam erupting things should be fine. If you are that worried turn the heater on full and the blower on max and you'll cool the engine a lot quicker - but may cook your feet.

Think my next task is to reconnect my digital thermometer and get some readings for the 1/4 and 1/2 way positions.

[GeoffSmith]

It's easier to plug in ElanScan and read the temperature...

Apart from having the peace of mind of a guage which behaves in the same way as almost every other car on the road, the real impetus for doing this was that having diagnosed many stuck thermostats worldwide from ES logs, I did not diagnose my own problems caused by a stuck (open) thermostat until I plugged in ES. The resolution of the dial at ¼ scale is not sufficient to differentiate between running normal and cool.

[Elanlover]

Still want one.............

Two maybe.

[Saltire]

Still want one.............

Two maybe.

Me too. Or at least the circus diagram and parts list so I can DIY

[lotusflasherman]

[quote="GeoffSmith"]It's easier to plug in ElanScan and read the temperature...

Apart from having the peace of mind of a gauge which behaves in the same way as almost every other car on the road, the real impetus for doing this was that having diagnosed many stuck thermostats worldwide from ES logs, I did not diagnose my own problems caused by a stuck (open) thermostat until I plugged in ES. The resolution of the dial at ¼ scale is not sufficient to differentiate between running normal and cool.[/quote]

Geoff, I agree in principle, but ... I've downloaded Elanscan software but haven't yet sourced a plug so it's not 'easier to plug in Elanscan' for me, yet. (It's on my 'things to do' list.) Got any spare USB's leads?

As I don't have your hi-tech diagnostics equipment I diagnose operation of a thermostat with my low-tech hand-held diagnostic equipment ... (this may be useful for others without Elanscan):-

Start a cold engine and as it warms up hold the radiator top hose - the one coming away from the thermostat housing, (told you it was hand-held ).
Top hose should stay relatively cool and then get hot quickly when the thermostat opens; if top hose warms up slowly with the engine the thermostat is stuck open.
Generally that procedure is only needed in summer - if you use your car in winter and the heater isn't very good ... the thermostat is almost certainly stuck open.

Anyway, as I said earlier in this topic that I'd check how the OE temp gauge graduations relate to degrees C and this is what I found on mine...

I ran up from cold and the needle moved off the rest at 37C, 1/8 (midpoint between 'rest' & 1/4) was 53C, 1/4 was 75C, 3/8 was 84C, 1/2 was 90C and the fans kicked in at 97C so it never quite reached the 5/8 position.
So if I was adding numbers to my OE gauge it would look like this...

temp.jpg

Interesting that I have some silver faced Lochwood dials to go in and noticed they print numbers on the temp gauge: 90C at the 1/2 graduation and 110C above a red block at 4/4 or 'H' on the OE gauge.

I also checked my thermostat as described above and that began to open at 72C, which seems a bit low to me, but my gauge normally runs on the 1/4 position ,as described in the manual. Parts Manuals only seem to list A100E6167S, so I'm now assuming that the manual is written for worldwide use with a 74C stat, which I appear to have in mine. Is the A100E6167S stat a 74C stat? Can anybody confirm or advise otherwise?

Your trace at the start of this post, John_W's trace and Elanlover's comment about his gauge running midway all seem to indicate that a stat in the region of 82C / 84C is fitted, which for UK use seems much more sensible.

My Eclat Manual says the 912 engine in Elite, Eclat & Esprit had a choice of 74C thermostat (A075K0121F) for High Ambient Climates or 82C thermostat (A907E6046Z) for Temperate Climate (UK) so been through my boxes in the garage and found I've an 82C, an 88C and a spare Cooper S one which, after cleaning up and putting on my glasses, I see is not 95C as I said earlier but 195F so that's about 90C. IIRC when a 195F stat was fitted the rad' pressure cap needed to be a higher one too. Think we fitted 15psi cap to give boiling at 120C rather than 13psi.

I also noted my fans came on at 97C and off at 95C, though water temp continued to fall past that by several degrees so some delay before it got back to 97C. John_W's trace shows his fans on at 109C and off at 101C.

Can you tell from your analysis of various Elanscan whether there is any matching between thermostats and Rad fan Thermal Switches?
Parts Manual only lists A100E6357S. If John-W and I have the same part and his operates between 109-101 and mine between 97-95 that's a pretty large production tolerance.