I continue to get erratic readings on my Temp gauge of my 88 240 gl. Perhaps someone can be of help.

The description of the problem is as follows. Car warms to operating temp and engine is NOT overheating. Gauge shows normal at first, then within five minutes (or thereabouts), temp reading rises to the RED ZONE. It will stay there sometimes for 10 minutes, sometime longer. Always drops to normal reading, and never is actually running hot.

As my car has many miles on it (240,000). I figured replace the cooling system part by part. Thus, I have replaced the radiator, fresh antifreeze, fan clutch, fan shroud, the temp sending unit, thermostat ([twice] 180 degree & 160 degree).

Gosh, I hope there is someone who may have a clue, as you can read, I don't, except to keep replacing parts.

Thanking all in advance who may offer help. regards T Ray