Uploaded May 2017 | Updated September 2026, 1 week ago
So we all know how important it is not to run out of engine coolant water (hopefully!). Also it's not unusual for some engines to use a little bit of water. Modern cars all have a water level warning system, but not a lot of older cars.
Here we fit a warning buzzer to an old LANDROVER Freelander 1, but a similar approach could be used with any car with the same parts.
Due to the water sloshing around in the tank, it is easy for the float switch that is used to give a false alarm if just wired direct to a buzzer.
So three different opproaches are presented for stopping annoying false alarms. The final solution I used on this Freelander was the last little circuit shown at time. 22:25. This circuit, while still being quite simple, filters out false alarms, but it also allows for continuous monitoring of the water level and will set off the warning beeper if the water level falls at any time while driving. The water has to be constantly low for more than 9 seconds.
For other cars with a squarer shaped coolant tank, which allows for a more horizontal position of the float switch, it may be the case that false alarms are never or rarely triggered by water sloshing around. If that's the case then you could connect the float switch straight to a warning beeper / buzzer or a light or even a speaking little microcomputer like the BBC microbit as shown in the video.
I have now changed the code in the BBC microbit shown in the video so that false alarms are filtered out by the software. If there's sufficient interest in this I'll provide more details later. It really is very easy to program those BBC microbit boards so don't think you can't do it.
I looked at fitting the same sensor on my mg zs, but the water level wasn't deep enough and the tank seam was in the way, so I couldn't use this sensor. When I come up with another solution I'll post that video as well.
Now here are some buying links:
For the float switch (beware of other switches that are only specified to work up to 85 centigrade):
On ebay UK: ebay.us/4ynogr
Others (more expensive) Amazon UK: amzn.to/2qdmB1Z
Beeper on Amazon UK: amzn.to/2qQGP0r
The capacitor 470uF 25v for the simple false alarm filtering on Amazon uk: amzn.to/2qQFXbZ
For building the better five part circuit shown at 22m 55sec these are the bits from Amazon UK:
Capacitor 2200uF 16v (or 18v or 25v is also ok): amzn.to/2qdgkUc
The 1k ohm resistor: amzn.to/2qQqhWm
The 3.9k ohm resistor: amzn.to/2qXs7mH
The 1N4007 diode: amzn.to/2qXOY3z
The zener diode, get the 5.6V version, on eBay uk:
rover.ebay.com/rover/1/710-53481-19255-0/1?icep_ff3=9&pub=5575193927&toolid=10001&campid=5337910930&customid=&icep_uq=bzy88+series+zener+diodes&icep_sellerId=&icep_ex_kw=&icep_sortBy=12&icep_catId=&icep_minPrice=&icep_maxPrice=&ipn=psmain&icep_vectorid=229508&kwid=902099&mtid=824&kw=lg
To request details on the microbit and program put in a comment on the video. If sufficient interest I'll get the details together, maybe in another video.
Subscribe to the channel for similar DIY, fixing stuff, car bits and tech reviews here:
youtube.com/subscribe_widget?p=comeinhandynow
Note, if you want to be notified of new videos click on the bell symbol on my home page.
See other videos on my channel here:
youtube.com/user/comeinhandynow
If anyone wants to show appreciation for any money savings, or just help support the channel and future videos then you now can. Use this link: paypal.me/comeinhandy
OR you can support me by using the Amazon and Ebay links to buy other stuff that you would usually buy, it will not cost you anything more, but will help this channel. e.g. Generally useful stuff:
Face mask:
Amazon UK: amzn.to/2GHE9d6
Similar ones on Amazon USA: amzn.to/2IHmip1
Eye goggles: Amazon UK: amzn.to/2IUSqos
Amazon USA: amzn.to/2GAtIXJ
Rubber disposible gloves are also useful, here's the links for
eBay USA: ebay.us/GGqmTJ
eBay UK: ebay.us/cE1BHK
Amazon UK: amzn.to/3aikbl8
Amazon USA: amzn.to/3cdwjpD
Amazon Canada: amzn.to/2Q0VHZm
Amazon Australia: amzn.to/2QlUawX
The video is about my personal opinion and experience and contains no paid for product placements. No responsibility is accepted for any perceived recommendation for or against a product or feature nor any consequential damage or harm since this video is just my personal experience. You accept by watching this video that you accept any responsibility for any subsequent actions or decisions that you take.
Note on copyright / licensing: This video was created using Apple iMovie and content is fully licensed. Additional music (no copyright songs) from the following source:
AndyM -Oasis [Faded NCS Release] youtube.com/watch?v=1C-EjJHn6SY
So we all know how important it is not to run out of engine coolant water (hopefully!). Also it's not unusual for some engines to use a little bit of water. Modern cars all have a water level warning system, but not a lot of older cars.
Here we fit a warning buzzer to an old LANDROVER Freelander 1, but a similar approach could be used with any car with the same parts.
Due to the water sloshing around in the tank, it is easy for the float switch that is used to give a false alarm if just wired direct to a buzzer.
So three different opproaches are presented for stopping annoying false alarms. The final solution I used on this Freelander was the last little circuit shown at time. 22:25. This circuit, while still being quite simple, filters out false alarms, but it also allows for continuous monitoring of the water level and will set off the warning beeper if the water level falls at any time while driving. The water has to be constantly low for more than 9 seconds.
For other cars with a squarer shaped coolant tank, which allows for a more horizontal position of the float switch, it may be the case that false alarms are never or rarely triggered by water sloshing around. If that's the case then you could connect the float switch straight to a warning beeper / buzzer or a light or even a speaking little microcomputer like the BBC microbit as shown in the video.
I have now changed the code in the BBC microbit shown in the video so that false alarms are filtered out by the software. If there's sufficient interest in this I'll provide more details later. It really is very easy to program those BBC microbit boards so don't think you can't do it.
I looked at fitting the same sensor on my mg zs, but the water level wasn't deep enough and the tank seam was in the way, so I couldn't use this sensor. When I come up with another solution I'll post that video as well.
Now here are some buying links:
For the float switch (beware of other switches that are only specified to work up to 85 centigrade):
On ebay UK: ebay.us/4ynogr
Others (more expensive) Amazon UK: amzn.to/2qdmB1Z
Beeper on Amazon UK: amzn.to/2qQGP0r
The capacitor 470uF 25v for the simple false alarm filtering on Amazon uk: amzn.to/2qQFXbZ
For building the better five part circuit shown at 22m 55sec these are the bits from Amazon UK:
Capacitor 2200uF 16v (or 18v or 25v is also ok): amzn.to/2qdgkUc
The 1k ohm resistor: amzn.to/2qQqhWm
The 3.9k ohm resistor: amzn.to/2qXs7mH
The 1N4007 diode: amzn.to/2qXOY3z
The zener diode, get the 5.6V version, on eBay uk:
rover.ebay.com/rover/1/710-53481-19255-0/1?icep_ff3=9&pub=5575193927&toolid=10001&campid=5337910930&customid=&icep_uq=bzy88+series+zener+diodes&icep_sellerId=&icep_ex_kw=&icep_sortBy=12&icep_catId=&icep_minPrice=&icep_maxPrice=&ipn=psmain&icep_vectorid=229508&kwid=902099&mtid=824&kw=lg
To request details on the microbit and program put in a comment on the video. If sufficient interest I'll get the details together, maybe in another video.
Subscribe to the channel for similar DIY, fixing stuff, car bits and tech reviews here:
youtube.com/subscribe_widget?p=comeinhandynow
Note, if you want to be notified of new videos click on the bell symbol on my home page.
See other videos on my channel here:
youtube.com/user/comeinhandynow
If anyone wants to show appreciation for any money savings, or just help support the channel and future videos then you now can. Use this link: paypal.me/comeinhandy
OR you can support me by using the Amazon and Ebay links to buy other stuff that you would usually buy, it will not cost you anything more, but will help this channel. e.g. Generally useful stuff:
Face mask:
Amazon UK: amzn.to/2GHE9d6
Similar ones on Amazon USA: amzn.to/2IHmip1
Eye goggles: Amazon UK: amzn.to/2IUSqos
Amazon USA: amzn.to/2GAtIXJ
Rubber disposible gloves are also useful, here's the links for
eBay USA: ebay.us/GGqmTJ
eBay UK: ebay.us/cE1BHK
Amazon UK: amzn.to/3aikbl8
Amazon USA: amzn.to/3cdwjpD
Amazon Canada: amzn.to/2Q0VHZm
Amazon Australia: amzn.to/2QlUawX
The video is about my personal opinion and experience and contains no paid for product placements. No responsibility is accepted for any perceived recommendation for or against a product or feature nor any consequential damage or harm since this video is just my personal experience. You accept by watching this video that you accept any responsibility for any subsequent actions or decisions that you take.
Note on copyright / licensing: This video was created using Apple iMovie and content is fully licensed. Additional music (no copyright songs) from the following source:
AndyM -Oasis [Faded NCS Release] youtube.com/watch?v=1C-EjJHn6SY
