Indicator stalks

[Galileo]

As per usual, plenty of info on this site on how to do something with a simple search.

[new to this]

Was that a new loom for the whole car or just headlight circuit's

Dave

Full front loom, lights, horn and in my case custom electric fan wiring. If you need a full loom then Autosparks will do one for somewhere in the region of £450 I believe.

Thanks,how are you controlling the fan,temp sensor in top radiator hose ?

Dave

[Galileo]

I've a CPU controlled (Arduino) PWM fan speed control system that I knocked together myself. It uses a sensor in the top hose to read the temperature, and if it senses a climb in temperature above 92°C it starts the fan on a low speed and if it does not see a drop in temperature it keeps increasing the fan speed until it reaches maximum or the temperature drops, if it starts to drop it holds that fan speed until it reaches 87°C and turns off.

I've gone way over the top, was bored one weekend.

[GrahamFountain]

I still say the sensor needs to be in the bottom hose measuring the temperature of the output from the radiator.

What's the point in running the fan if the air flow from moving the car is already causing a big enough temperature drop? In that case the fan will add nothing to the effect except waste power.

This is what I had with a sensor in the top hose - the fan was on when the thermostat wasn't open properly, and there wasn't enough water flow for the fan to have any effect - just enough flow to fill the top hose with hot water. Now it's in the bottom the fan only comes on when it's actually needed - I have a pair of sensors on the radiator ends connected to digital readouts on the dash so I know what's happening.

I'm still thinking about adding a linear sensor in a divider, a two point voltage comparator with relays, and a high power resistor, to give a two speed fan though. I think I have all the bits somewhere.

Graham

[Galileo]

I was more interested in engine temperature rather than a how well my radiator works reading. Ideally I would imagine a sensor in both locations could be useful, to know engine temperature as well as cooling efficiency. Like I say, I went OTT, I could have gone down the route of most OEMs and just used a bimetal screw in fan switch, either in the top hose or two thirds up the radiator if I replaced that as well with an ali one, but where's the fun in that?!

[Carledo]

I'm currently building a sub loom, for a customer's Sprint, 4 relays (Dip, main, start, fan) with 6 fuses, l/h dip, r/h dip, l/h main, r/h main, fan and a takeoff fuse to provide dip beam power for a rear foglight. All done with correct Lucas colour coded wire and fitted with Rists connectors to fit the original plugs at the business end!

I'll put some pics on later, but it's designed to fit on the O/S flitch above the battery, keeping the high current leads to the lamps themselves as short as is practical.

Steve

PS on the matter of blade fuses versus glass fuses, I wouldn't give you tuppence for the glass fuses and certainly wouldn't introduce more of the awful thing into any of my (or my customers) cars! In fact i'm researching methods of making a "bus bar" section to convert a 6 blade fuse box to be used as a direct replacement for the 2 glass fuse original This will have 4 ignition live fuses and 2 permanent as that's how many wires are on the original car. Of course, if you REALLY want to go OTT, you can have something like this!........



14 fuses in here and 2 spare positions with most ignition controlled circuits on separate fuses plus feeds for pemanent live, sidelight and ign aux lives. The headlights, spotlights horns and fan are run from a second fusebox elsewhere in the car. But this much work demanded a more or less bespoke loom for the dash and underbonnet area!

[GrahamFountain]

The sensor in the bottom hose does need a lower on temperature, and might need a different level of hysteresis, but it controls the fan to control the engine temperature not responds whether that response is meaningful or not. If you have another problem making the output over hot for a cold input, you have, by the very definition given, another problem.
And there are those who are probably better off not knowing even if the fan is on or not, based on the assumptions they make. Like saying the fan shouldn't ever come on while you're moving - I've seen one situation where it came on and stayed on, quite correctly, at 30 mph. And that situation might have applied to at least 60 mph in some cases, possibly more.

On the relays, if there's room, why not relay the washer and horn switch too? I did the washer and am already wondering about the horn switch becoming old. A couple more for the indicators (though I admit that's not so simple), and that's the set i'n't it?
As to location, it don't worry me, but hiding the relays up above the cardboard under the dash maintains the look of originality a bit better. Maybe taking feed off the input brown wire would add to that, if it's reasonably accessible down there without having to resort to scotchlocks.

As to round fuses vs blades, I just ain't doing with a mix. The glass ones work well enough for me mostly, and again there are those who would only make the change if the blade fuse box fits under the same cover at least.
That being said about glass fuses, I just found a new one that was actually a 150 Ohm resistor. That made fault finding a pain - there was 12v on the load end of the fuse with no load on it, but connected up with a lead that checked OK for continuity, there was (near enough) 0 volts in the load without blowing the fuse.

Graham

[GrahamFountain]

One of the CDs (coffin dodgers) at work says I ain't explained the reason for putting the switch in the bottom hose well and should try again.

Think about this situation:
You're driving along with the engine warmed up and the thermostat well open but there's a good airflow through the radiator, so the fan is off.
Then you stop.
The first thing that happens (in terms of temperature) is that the temperature of the water coming out of the radiator and going into the engine starts to rise, though the temperature coming out of the engine and going into the radiator stays the same.
It's at this point that you want the fan to come on.
What you do not want to do is to wait till the hotter water has gone all the way through the engine and is coming out extra hot before the fan turns on. You want the radiator to go back to delivering cooled water ASAP, ideally before there's even any rise in temperature at the engine outlet, never mind enough to register with the fan switch as abnormal.

The delay for the sensor at the top to react may not be much. And the temperature the engine peaks at may be only a little hotter than with the switch in the bottom hose. But every little helps.

Graham

[Carledo]

One of the CDs (coffin dodgers) at work says I ain't explained the reason for putting the switch in the bottom hose well and should try again.

Think about this situation:
You're driving along with the engine warmed up and the thermostat well open but there's a good airflow through the radiator, so the fan is off.
Then you stop.
The first thing that happens (in terms of temperature) is that the temperature of the water coming out of the radiator and going into the engine starts to rise, though the temperature coming out of the engine and going into the radiator stays the same.
It's at this point that you want the fan to come on.
What you do not want to do is to wait till the hotter water has gone all the way through the engine and is coming out extra hot before the fan turns on. You want the radiator to go back to delivering cooled water ASAP, ideally before there's even any rise in temperature at the engine outlet, never mind enough to register with the fan switch as abnormal.

The delay for the sensor at the top to react may not be much. And the temperature the engine peaks at may be only a little hotter than with the switch in the bottom hose. But every little helps.

Graham

I'm sorry, kinda have to disagree with your science here!

When you switch off a fully warm engine, the hottest part is the metal block. Which transfers heat to the water within it. Because it's no longer being circulated by the pump, the water in the BLOCK gets hotter. But because the thermostat is still open (it works independent of electricity) there is a tendency for the thermic syphon effect to let this hotter water move into the top hose and thence into the radiator, so the best place for the thermostatic fan switch is STILL the top hose!

However, as a CD in training myself, I have the old school guys fear of leaving anything electrical running after the engine is switched off and no longer charging the battery. I know it's not so much of an issue these days with better battery technology and high amp alternators but old habits die hard. So my fan sender switch is ignition live only and won't run once the engine is switched off under any circumstances! I can't say it's ever caused me a problem!

Steve

[GrahamFountain]

When you switch off a fully warm engine, the hottest part is the metal block. Which transfers heat to the water within it. Because it's no longer being circulated by the pump, the water in the BLOCK gets hotter. But because the thermostat is still open (it works independent of electricity) there is a tendency for the thermic syphon effect to let this hotter water move into the top hose and thence into the radiator, so the best place for the thermostatic fan switch is STILL the top hose!

Notwithstanding whether that's a good idea or not (my fan system is switched off the ignition - I don't care what happens when the pump is off), or how much, if any, of that thermal siphonically driven water gets into the radiator (overshoots and goes down-hill?) where the fan might cool it, it would want a separate control circuit, i.e. with its own relay, running off a separate sensor. I would suggest a simple comparator connected to the temperature sender in the block enabled by turning the ignition off. Less than £2 and 2 weeks lead from China (possibly with a cut-off timer as well).

With regard to cooling the water pumped through the radiator: Whatever else is happening anywhere, if the the water coming out of the bottom of the radiator is cool enough, the fan being on won't do anything that matters, so it shouldn't be on.
But if the water coming out the bottom of the radiator is hot enough,the fan should be on.
So the obvious place for the sensor controlling that is in the bottom hose.

The questions then are what temperature is hot enough and how much hysteresis should there be?
There might also be some subsidiary questions about multi-threshold, multi-speed fan control and or the use of a PID (at least PD) controller.
Would the use of Kalman (filter) gear be restricted to Beetle derived sports cars?

Graham

[GrahamFountain]

As a matter of interest, I watched thje readout from the sensor in the top left corner of the rad after I switched the engine off this morning. While it only updates every 10 seconds or so, it showed a consistant reduction in temperature for the first miniute. After that, I went in to work.

Graham

[GrahamFountain]

In addition to the problem of getting the heat into the area of the radiator actually cooled by the fan through thermo-siphoning, i.e. against the thermal gradient beyond the thermostat housing, there's a problem with their susceptibility to being locked from any gas pockets forming at the top of the system that hadn't poked me in the eye on first reading the suggestion. Don't know about yours, but I always seem to have some void when I open the screwtop on the doly and wondered how much would be needed to stop the whole thing cycling.

The traditional solution to both problems seems to have been to mount the rad much higher than the top of the engine, so there'd be room for a bubble and no thermal gradient to push the heat up. But there being no room for that, unless you're up for lowering the engine (to coin a phrase), you may to have to have some sort of gas/vapour removal system built into the thermostat cover.

BTW I don’t normally worry overmuch about that bubble because the pump will shift it easy, as soon as the engine starts, and turbulence will disperse it stat. And the loss of thermal capacity of the coolant from a few bubbles in the coolant can't be enough to worry about.
Interestingly, there are 12v PID controllers with 20A relays built in available on eBay for under £4 from China. I worry how volatile the 3 term settings are if they lose power — resetting it every time the battery goes flat could become wearing. And the EMI issues with the sensor lead may be a concern. The temperature displays I have in the cabin were driven nuts by the ignition system before I screened their leads. And there still a bit wobbly when the engine is running – about 1 in 10 readings is proper bolloxed. I 'spose I could open them up an' shove a really big cap in there, but I can't do that while driving and it don't annoy me else. The problem in doing that with a PID controller, where spikes in the input will bugger the differential term, is a really big cap will also tend to nullify that differential term. But, considering how far over the top a Kalman filter would be and at < £4, I may just buy one and see.

Graham

[Galileo]

Did some research, avoiding internet forums where there appears to be an age old debate of top or bottom with valid reasons given for both locations but with no actual scientific backup to various claims.

Doing a library search at work I've come up with quite a lot of interesting current day thinking on cooling systems. This is probably not news to anyone with a modern car but as my newest vehicle is a 1998 truck that stopped being made because it was too basic and rough for modern markets, I'm a bit out of touch. I'm probably going to absolutely bore the pants of anyone reading further but I felt it was interesting enough to share, honest, not because I wasted an hour of my life rifling through research papers and publications and you'll damn well better pretend this is good s##t.

Current thinking is to keep the coolant within the range of 85°C to 110°C, this can be achieved with a mapped electronically controlled cooling system. This allows for the regulation of temperature depending on engine speed, load and throttle position. For example for maximum performance at part throttle a higher temperature is sought after in the 95 to 110°C range though at full throttle that drops to 85 to 95°C.

This precise temperature regulation is achieved with electronically controlled thermostat, dual speed fans and finally getting to the relevant point, measuring sensors in both the engine outlet and the radiator outlet. The ECU reads the temperature, engine load and throttle position and compares this to a stored map and adjusts the fan speed and thermostat to match.

One interesting side effect of this electronic control and wide temperature changes is the interior heating can be affected by large temperature change, so the design also calls for an electronically controlled water valve for the heater so as to maintain a set heat setting.

My system is wrong, I do need to have a sensor in the bottom as well as the top hose to be able to correctly regulate the fans to maintain a set temperature, the only thing is that it will be a compromise temperature, pretty much the same point arrived at as what the engine designers came up with 50 years ago. I'll probably still have to pop the bonnet open after a fast run when hitting a long traffic queue when it's hot out to give the poor old thing a bit more breath, and with the added bonus of the classic whiff of evaporating petrol vapour from the carbs.

Worst discussion on indicators ever this thread!

[Carledo]

Because this thread has gone so far off topic, I was going to continue it in a new thread titled "How hot is too hot?"

In fact, I think I will!



In the meantime and a bit closer to topic for a penance a pic of the relay loom i'm currently building for a customer!




It's not finished yet, have to try fit it to a car to get the lengths right and then fit the Rists plugs and tape it all up.

Steve

[GTS290N]

.............
i'm researching methods of making a "bus bar" section to convert a 6 blade fuse box to be used as a direct replacement for the 2 glass fuse original This will have 4 ignition live fuses and 2 permanent as that's how many wires are on the original car. ................

I trained in electrical/electronic but I'm lazy - if you build a drop in replacement I'll buy one! I even bought a fuseboard - a year ago...