Thread: coolant level and oil pressure alarms - TD5s

Originally Posted by feraldisco

Hi - these clearly seem like good ideas on a TD5 in particular. Presumably you want the coolant alarm to be placed as high as possible - where's the best place to insert this on a 99 TD5 Disco?

Is anyone aware of a readily available oil pressure alarm?

There are several 'theories' on the location of sensors.

There is one view that a sensor fitted in the top hose at the point where it goes into the radiator is best, but as pointed out by others - if the water level begins to drop - water will still be pumped through the top hose even when the water level is dropping, and - again theoretically the water could drop to a very low level - before water would cease reaching the pump and not be pumping water.

I would tend to concur with that view.

The other veiw is a sensor in the expansion/buffer/header/overflow tank - where it measures the level of water in the sytem by a float switch -

This in my opinion is the better way of doing things.

Many use float switches - with make contacts on fluid drop - I would prefer to have a float switch mounted upside down to break contact on water drop - then if the switch fails - there is a failsafe

The best of both worlds in my view is to fit a sensor (passive - just a thermal probe - less to fail or break) in the expansion/buffer/header/overflow tank (whatever anyone wants to call it)

Just my opinion though

To fit a pressure alarm would be fairly easy - if you have an access port to fit a sensor/switch - I guess you could put a tee in where the original oil pressure switch/sensor is located.

The switch would need to be set at a 'safety zone' set point - so it alarms when the pressure drops to below a 'known' safe level.

If either of these alarms are used - you might also want to consider a delay timer - especially if you have audible alarms - as I am sure that every time you switch the ignition on (more so with oil pressure) the buzzer would sound until the engine is running and oil pressure up to 'norm'


Again just my opinion

Originally Posted by ladas

Many use float switches - with make contacts on fluid drop - I would prefer to have a float switch mounted upside down to break contact on water drop - then if the switch fails - there is a failsafe

The float switch used here is normally closed, and opens when the level drops:

http://www.aulro.com/afvb/showthread.php't=39325


Paul