In the mornings, engine heats up to normal operating temp (210 deg. ) then floats from 210 to near redline then back to 210 deg. on highway driving. This cycle takes about 1 minute.

When I exit and come to the red light, the temp sometimes climbs to near redline then doesnt drop tuntil I start rolling, other times it stays at 210 deg. ?????

My question is/are would a clogged radiator or defective fan cluth combination cause this symptom?

Water pump changed in March 2013, thermostat changed in August 2013.

1996 XJ 217,000 Daily driver.

 

Fan clutch would be my guess

 

Could be fan clutch, could be radiator, could be that you got a bad thermostat right out of the box, could be your radiator cap isn't holding pressure, could be that your electric fan isn't turning on, could be that you have a blockage somewhere and you need a good flushing, could be that your fan shrouds aren't in place.

Point is it could be a lot of things that are covered here daily that you need to do a good searching for.

 

Sounds like a bad fan clutch, but don't overlook you electric fan also. Radiators do go bad, but those will usually show symptoms, like a leak. Usually, but not always. Also make sure your coolant/water mixture is correct. Too much coolant will cause overheating. Sometime as people replace components, they don't realize they're mixing their coolant incorrectly.