Chevrolet Repair: Overheating engin at highway speed, highway speed, cotton wood

Question
Mark I own a 1992 Blazer S-10 2wd Five speed. It has about
180,000 miles on it. It smokes but only after it has set for a while
and only at first start up! It runs great but has started
overheating lately at highway speed. I have changed the
thermostat (twice) and flushed the cooling system. The water
pump seems to be working OK. I can watch cooling pass thru
the radiator quiet rapidily. I am not loosing any coolant. The top
hose is hot to touch after warm up.The radiator seems clean and
not stopped up. I do get a little water out the exhaust after the
car sets for several days at first start up. Any Ideas?

Answer
Hello Mike, I would check the front of the radiator for any weeds,leaves or cotton wood. I have seen the front of these plug with stuff that just floats in the air. If it has A/C it is a good place to start. If it is clean, I would have to say that the radiator is plugged in the lower part and not cooling the coolant. It could look good on the top but not flowing on the bottom.

Hope this helps

Mark