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MG MGF Technical - Simple coolant level sensor solution

Hi all,

I've just fitted a coolant level sensor to my MGF, using a slightly different and simpler approach to the (already excellent) instructions on Dieter's website: http://www.mgfcar.de/expansion_tank/level_sensor.htm

I used the late-type expansion tank and sensor as per the website, but instead of using a buzzer, I connected the sensor into the circuit for the "Engine Bay Overheat" warning lamp. This involves minimal wiring - the sensor simply connects between earth and the wire from the ECU to the warning lamp. On the VVC model this is pin 31 of the top ECU connector, green wire with red stripe (may be different on an MPI). No tricky wire routing or dismantling of interior trim required!

The warning light will still work as normal if the engine bay temp gets too high or the AAT sensor fails, and you still get the lamp-check when the ignition is turned on, but it will also light up if the coolant level drops. I prefer this solution over the buzzer, not just because it's easier, but because there's no risk of failing to hear the buzzer if you're pushing on a bit (especially with the top down) or have the stereo turned up loud! :o)

The only drawback is that the light coming on could mean one of two different faults - but since you're going to need to stop anyway, it shouldn't be too much of a problem...

Hope this is useful to people, any comments welcome.
J Nuttgens

Sounds like a good alternative, but I shouldn't worry about not hearing teh buzzer on the other systems. I have had the misfortune of hearing it whilst as you say "pushing on a bit with the hood down and radion turned up". Yu would have difficulty missing it.
David

This seems to simplify an already good accessory. You miht do a lot of people a favour if you could persuade B&G to build your mod into their kit.

Chris
Chris

I can hear the B&G buzzer with my bone dome on, while driving full pelt with the roof down at Silverstone... yeah, it's plenty loud enough! LOL

JN, I think that your solution is a master stroke of simplicity! A very elegant solution! :o)

The one advantage that the B&G kit does have is a 'damper' that prevents the warning from being set off over rough roads, or hard cornering. Whether that's worth 80 quid to you is very much up to you, but for me it has been. I've got my warning light connected up to the unused catalyst overheat warning lamp... :o)
Rob Bell

Next time you are <pushing on a bit>, work out how often you look down at the EBO light and if you would see it with the sun shining direct on it. I am sure the answers will be, "Not often enough to catch a HGF" and "No Way".
The Start up Check will still show if the bulb is OK and the EBO & EEC circuit work but will not show a failure of the Coolant Level Warning.
Geoff F.
G. Farthing

Nice option in any way for the hard core DIY'er with late ECD3 ECU ;)
I've put that on site.
Dieter

Thanks for the comments. Geoff, I appreciate what you're saying, but you certainly don't need to be looking at the dashboard to see the light come on. I've already noticed it flicker on several times on tight left-handers (where the coolant surges to the opposite side of the tank to the float). I did the same installation on my last car (Rover 200), which did its job when the rad sprang a leak, and my other car (Pug 205 GTI) has a warning light as standard which has saved the engine several times when coolant hoses have split. I admit it might be difficult to spot if the instrument panel is in direct sunlight though.

No the lamp check won't show up a level sensor failure but then neither will any of the other solutions. Fast left-hand bends are a good way of checking that it still works however! ;-)

Dieter, thanks for adding it to the website but I'm not sure what you mean by the ECD3 ECU - my car is a '96 VVC with MEMS 2J ECU. It should work on other models too but the warning lamp wire may be on a different connector or pin number.

I might think about adding a delay circuit to prevent false alarms - so far I haven't found the occasional flash from the lamp annoying or distracting but I guess it could be when driving at night.
J Nuttgens

This thread was discussed between 11/04/2007 and 13/04/2007

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