Coolant light in 1990 300 se

Assuming you have no leaks the low coolant light is actually a de facto change coolant light. If it’s been more than two years since you’ve had the coolant flushed and refilled, it is time to do it now. That enough water has evaporated and vented out to the point where the low coolant light is on, it has been in there for a while.

In the mean time just add water to the plastic expansion tank located on the LHD passenger wheel well, it will have a metal pressure cap on top and a coolant line running to the bottom of the radiator. Add enough water for the dash light to go off, no more.

I’d recommend taking the car to a good MB indy for the cooling system flush/refill.

Antifreeze and coolant are the same thing – where I live its ‘coolant.’

Post in the w126 forum from now on.

As I do things like this myself I really have no idea how much it would cost, I would think less than $100 if that much. Since you’re replacing the coolant adding more would be a waste of money; you also need to use MB coolant. Use tap water for now, it will keep the engine cool and not harm anything until you get it to a shop. Just ask for cooling system service which should include a flush, pressure and leak test, and a refill of the proper coolant at the correct mix.

Your 300 SE is a 126 chassis car, posting in that forum will get you more responses as that is where other 126 owners post and read.