My 99 Nissan Almera has been sitting unused for a few months, and I just went out to start getting it up and running again. I noticed that the coolant in the reservoir was a bit low ( but clean looking ) and decided to check if the coolant in the radiator needed topping off. When I opened it I noticed this gunk around the filler neck and on the pressure cap:
And here's a picture of the cap ( I had already started wiping it off before I thought to take a picture ):
The truth is that if I was buying a car and I saw this under the radiator cap I'd assume there was a head gasket problem and not buy it.
I only had to add a tiny amount of coolant to top off the radiator, and I didn't see any evidence of foaming or frothing under the oil fill cap or on the dip stick. After starting the engine I had "white smoke" for a few minutes, but I'm guessing that it was probably just steam as the car's been sitting for a while and probably had quite a bit of water condensation inside.
I was planning on putting new shocks and brakes and going to pay the annual registration, do the annual test, etc.. tomorrow, but if there's a strong chance I may have a blown head gasket then I'll have to rethink all that.