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Build a Coolant Level Sensor for 2nd gen S40 & V50 Volvos


Why Build a Coolant Level Sensor?

MadeInJapan builds his own coolant level sensor for his S40 because this common item was not included on 2nd generation S40 and V50 models, oddly. I’ll let him explain:


Well, because our cars don’t have a sensor in the expansion tank (reservoir) to tell you when your coolant is low. This is a huge Volvo over-sight, or is it? Is it just another way to make more money from us? This should be the first defense against losing your coolant and overheating and rendering your Volvo as pretty much toast! Ask the many members on the different forums whose lower radiator hoses broke and immediately shot their engine temps through the ceiling, toasting their aluminum engines.

This makes sense. I have one (standard equipment) in my 1997 Volvo 850. I didn’t know they weren’t in the Volvo P1 cars. Not good. Ok, so this isn’t a good thing… but what does this mean to P1 S40 and V50 owners?

It Almost Got Ugly, Really Ugly

I’ll let MadeInJapan explain further:

I had a close call yesterday. It wasn’t a hose but after getting to work, I looked out my window and saw coolant all over the ground under my car. My expansion tank had cracked and spewed my coolant out. Fortunately for me, that was the extent of my loss! I got some fluid from the local auto parts store and although I looked for a replacement reservoir, I could not find any from our local parts stores so went to the dealer for full retail price. Still, better than a blown engine.

So, I wonder, why is there a windshield washer fluid level sensor but not one for the coolant?
I’m working on a, I hope easy solution, to add a level sensor to our expansion tanks, tie into the wires from the window washer tank so that you will get a warning on your dash if either of these tanks are low. When the message comes up on your dash, at least this way, you know to get out and check your coolant level.

I’ll keep you posted in regards to this. In the meantime, if anyone here has any ideas on this, please let me know. As things are progressing, I’m thinking that this is going to require a placement of a float in the reservoir, hopefully from the top with a locking washer on top so the tank will still hold pressure.

Adding a Coolant Level Sensor!!

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