93 Riviera and it gets hot after being driven about 20 miles. It's consistent too?
Given the age of the car I'd suggest a good cooling system flush and replace the thermostat. Be sure to install a 195°F thermostat. HTH. -Jim
And in addition do check your radiator hoses while the engine is running to determine if the hoses are collapsing thus restricting water movement.
In addition to the above suggestions.....are the cooling fans working? The fan on the motor side is the first to turn on...then if you turn on the A/C the one in front of the radiator starts...as the engine warms and the temp gets up to around 230 they both kick on HIGH. You can check the fans by running 12v directly to the connector, they are controlled by relays...they could be bad
Looking for a Used Riviera in your area?
CarGurus has 119 nationwide Riviera listings and the tools to find you a great deal.
Search Buick Riviera Questions
Buick Riviera Experts