You made the right call.
While you have the radiator out, check the hoses closely -- especially the lower hose. With the engine running at fairly high RPM's (i.e. on the highway) the suction on the lower hose is significant enough to cause it to collapse if it is weak or if the spring is missing. Sometimes the hoses start to separate on the inside, creating a restriction. If you have any doubts, just replace the hose(s) while you're there.
This can create a situation where coolant flow is lessened under the very conditions where the engine is creating the most heat. The result is overheating while cruising.
When you slow down (i.e. get off the highway) and the engine is running at lower RPM's, the pressure in the system becomes more equalized, expanding the offending hose, and the engine cools itself back down.
Wayne.
While you have the radiator out, check the hoses closely -- especially the lower hose. With the engine running at fairly high RPM's (i.e. on the highway) the suction on the lower hose is significant enough to cause it to collapse if it is weak or if the spring is missing. Sometimes the hoses start to separate on the inside, creating a restriction. If you have any doubts, just replace the hose(s) while you're there.
This can create a situation where coolant flow is lessened under the very conditions where the engine is creating the most heat. The result is overheating while cruising.
When you slow down (i.e. get off the highway) and the engine is running at lower RPM's, the pressure in the system becomes more equalized, expanding the offending hose, and the engine cools itself back down.
Wayne.