Hi.

I replaced the monovalve in my 89 420SEL (112K on it) this weekend and I took it out for a short drive afterwards.
The next day I noticed the car had leaked coolant (it did eventually stop because most of the puddle had evaporated).
So it appears that I did something wrong in the replacement. Would anyone be able to tell me how to be certain to be sure the valve is replaced & seated properly?

TIA,
Clay