Expert: Vern Bullock - 8/9/2011

Question
QUESTION: I have a 1980 el camino that is overheating when i drive it a 75 mph. whne i slow down it seems to not over heat. I have replaced raditor, water pump, fan clutch, fan blade, antifreeze. what is the normal operating temp

ANSWER: Hi Randy:
Did you replace the thermostat when you replaced the radiator?
Engines get hotter at high speeds, so the thermostat should
remain open all the time. Sounds like this is not happening.

---------- FOLLOW-UP ----------

QUESTION: yes I did replace the thermostat about a week ago, could I have gotten a bad one? what would be a ggod operating temp? thanks

ANSWER: It should operate at between 190 and 225 degrees.
Anything over 250 is too high. You may have the
wrong type of thermostat. Check the temp rating
on the box to make sure it will open and closed when
temps are in the 190 to 225 range.

---------- FOLLOW-UP ----------

QUESTION: Are you saying that the thermostat should open at 190 and close at 225  ??? thanks again

Answer
No. The thermostat should open at the temp. it is
rated to open. If that's 190 degrees, then it will
open at 190. If its 210 degrees, then it will open
at 210. If your engine is designed to over heat at
190 degrees and you have a 210 degrees thermostat,
the car will overheat before the thermostat ever open.

The thermostat is design to open and push anti-freeze through
the engine to cool it down. Once the engine has cooled down
below operating temp, the thermostat closes until the engine
heats up again.

The 1980 El Camino came with both small block V6 and a V8 engine.
3.8 L (229 cu in# Chevrolet V6
3.8 L #231 cu in# Buick V6
4.3 L #262 cu in# Chevrolet V6
4.4 L #267 cu in# Small-Block V8
5.0 L #305 cu in# Small-Block V8
5.7 L #350 cu in# Small-Block V8
5.7 L #350 cu in) Diesel V8

Make sure you have the right thermostat for your engine.