Coolant Level Sensor

[shalmaneser 26]

Background: My old coolant level sensor managed to fail in a particularly spectacular way, when the brown gunk sealant stuff suddenly let go and the sensor popped out of its housing, turning the low level light on and convincing me the HG had gone at the same time.

 

Once I had convinced myself the engine was fine I cut out a piece of plastic and siliconed it into the threaded cap part, which has kind of worked as long as I check the water fairly regularly as some does tend to creep out round the seal when the system is hot.

 

Sooooo what i need is either a blanking plug, and just check the water every week (which I do at the moment) or a cheap source of sensors, which seem hard to come by. Has anyone else had this problem and how have they solved it?!