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Howto A Locost over heat warning lamp
britishtrident - 8/9/09 at 06:05 PM

All that is required is a 12v Red LED from Maplins.
Suitable cheap N.O. thermal switch see photo --- cost less than £2.50

Just add some wire and connectors and sleeving.


This type of switch is availble with NO and NC contacts with working tempertures from about 30c to about 140c.

I used a 95c switch which seems OK for my Rover K application



[Edited on 8/9/09 by britishtrident] Rescued attachment 62.jpg
Rescued attachment 62.jpg

britishtrident - 8/9/09 at 06:08 PM

Mount on a suitable metal surface somewhere on the top of the engine that gets hot, Connect one connector of the switch to earh the other to the negative connection of the LED Rescued attachment S70.JPG
Rescued attachment S70.JPG

britishtrident - 8/9/09 at 06:11 PM

LED is mounted on the Dashboard and the the red wire connected to a suitable ignition 12v supply. Rescued attachment S3.JPG
Rescued attachment S3.JPG

James - 8/9/09 at 06:16 PM

Nice tip!

Cheers,
James

Guinness - 8/9/09 at 06:25 PM

Nice!

I could really have done with one of those. My temperature sender in the coolant was in the top of the thermostat body and when I lost water, ended up in hot air.

Mike

l0rd - 8/9/09 at 06:42 PM

Excellent tip but I would definitely add a really loud buzzer as well.

britishtrident - 8/9/09 at 07:30 PM

Better pic of the actual type I used

See ebay item r 320366193652

Sellers has switches for a range of temperatures be sure to get N.O. type (ie normally open) Rescued attachment 10.jpg
Rescued attachment 10.jpg

Cubby - 8/9/09 at 08:29 PM

sounds an excellent idea. What temp does your K series normally run at ? How much overheat does your system have if the switch makes at 95C ??

omega0684 - 8/9/09 at 09:31 PM

surely that only measures the temperature of the rocker cover though?

britishtrident - 8/9/09 at 10:17 PM

quote:
Originally posted by omega0684
surely that only measures the temperature of the rocker cover though?


Dosen't matter all you have to do is make an educated guess at the temperature that particular part of the engine will reach when the engine goes into an overheat scenario.

The coolant temp on the K series is normally pretty well controlled by the PRRT thermostat at 90c, prolonged idling on a hot will send the coolant temp up to 105c before the fan goes on to high speed and should bring the temp down pretty fast. Under radiator pressure the coolant will boil if the temp goes above 118 to 122c but coolant a temp above 110c is too hot for my liking.


With the coolant temp at 108c I measured the surface temperature where the extra switch is fitted with the plastic cover fitted over the plugs and coils at about 92c . The switch currently fitted operates at 95c and in normal running hasn't triggered yet. If the 95c switch gives too many false warnings I will simply drop in a 100c or 105c switch.

Peugeot have a similar system as a fail safe where an extra temperature switch bolted to the engine shorts the coolant temperature sensor to earth if the engine goes into overheat.

That won't work on a Rover system because the dashboard gauge and its built in overheat warning lamp are driven by the MEMS ECU. The Rover MEMS ECU is programed to ignore any input from the coolant temperature sensor that it sees as false, as a result I have seen cars with the engine boiling but the temperature gauge planted on "N".



[Edited on 8/9/09 by britishtrident]

l0rd - 9/9/09 at 07:32 AM

So ideally, you should use a temperature sensor of 90 degrees in order for you to be aware of the situation that the temperature is already on your ideal limit.

I would personaly use a 80 degrees sensor as i am used to my engine running cold. I believe my thermostat is set on 83.

[Edited on 9/9/09 by l0rd]

britishtrident - 9/9/09 at 05:53 PM

Little point in having an overheat alarm that activates at normal running temperature.

Since the late 1970s the thermostat temperature manufacturers have be using has been rising, if you look at the thermostat and fan cut in temperatures for say a Ford Zetec you will see they are much hotter than an xflo would be ever expected to run at.

Mark Allanson - 10/9/09 at 08:09 PM

These switches are rated 110v-240v AC, are there any issues using them with 12v DC?

MikeRJ - 10/9/09 at 10:20 PM

quote:
Originally posted by Mark Allanson
These switches are rated 110v-240v AC, are there any issues using them with 12v DC?


For driving a small warning lamp, none whatsoever.

Typically contacts have a lower DC current rating than AC, because with AC any arc tends to suppress itself as the current passes through zero. This is only a problem if you are using the contacts near their maximum rating though.

RK - 2/1/10 at 11:57 PM

Where would be a good place to mount this sensor? Thanks!


http://picasaweb.google.com/lh/photo/_L2u-AV47y4HvrtF88lc7g?authkey=Gv1sRgCLfsoZrNyoKG4QE&feat=directlink

RK - 11/3/10 at 09:55 PM

I mounted mine on the head, using the small screws holding the coil bracket in place. It actually works too, surprisingly enough. I used a 100 c switch, tested with a heat gun. Thank you Mr. Trident for the suggestion!

Cost: $11 for 10 Fleabay switches, plus some scrap wire and connectors: Ignition on + ve to small LED, Earth to switch on engine and other tab on switch to engine block earth.

Anyone really need a switch, let me know: 100 C Normally Open.

Sprytny - 24/3/10 at 09:23 AM

I was following the thread, and I am wondering where I might be able to obtain a temperature reader that informs the driver of the actual temperature. I am looking for a pretty straight forward one, and I can perhaps mount the sensor on top of the head perhaps, or even above the radiator. Please let me know...I tried maplins but they have the one mentioned here, which is great but I like to know my running temperature!

Greg

RK - 3/4/10 at 04:02 PM

Does your engine have a water temperature sensor already on it? That goes to the gauge, which tells you operating temp.

Not to be confused with the Coolant Temperature Sensor for the ECU. My engine is a Nissan CA18DET, so much different from most of you.

Oil temperature sensors are mounted under the engine, on the side, next to the filter. You can get a take off plate for the filter and mount a temp as well as an oil pressure sensor.

[Edited on 3/4/10 by RK]

stevegough - 29/5/11 at 06:54 AM

British Trident,
you are going to have to edit and move your pics to the left of the screen now, as the auto resize feature is shunting them off - screen where they can't be seen!

owelly - 29/5/11 at 08:52 AM

I fitted a similar device to my Bongo but used four temp switches. 80, 85, 90 and 100, with four leds. Job done.

RazMan - 29/5/11 at 09:46 AM

quote:
Originally posted by owelly
I fitted a similar device to my Bongo but used four temp switches. 80, 85, 90 and 100, with four leds. Job done.


That'll be a locost temperature gauge then LOL

ElmrPhD - 8/12/16 at 09:59 AM

This looks like something I gotta have. (Especially as I try to work out if my Omex ecu can share the Honda oem sensor with my Dash2 (requiring a pull-up resistor). Anyone have a clue???).

Let me ask if you think some heat-sink paste between the sensor and the engine would be a good idea?

Cheers,
Steve, in the NLs