Weird possible overheating symptoms
 

Daughter drives the Disco II

says the following has happened twice

the temp gauge slowly creeps up to hot, light comes on. As she tries to safely pull over, the gauge drops back down to normal.

what could cause this?

seems to be creeping up to overheating and then cooling down with the engine running.

How is the coolant level in the coolant reservoir? And does what she reports happen a steady cruising speeds or only in stop and go driving?

Steady speeds. On hwy coming home from college and then to work today.

She's off and doesn't go back to school until Monday. So I am going to drive it around tomorrow with computer connected.

I'll check the levels tomorrow. I just got the "Hey Dad, forgot to tell you earlier"

Truck is cold, coolant low, temp sender is in air pocket, gauge starts reading hot in air pocket: boom! thermostat opens and coolant starts flowing by sender and gauge reads cool. Just a thought. Check coolant level and make sure the system is bled. Then find out why the coolant was low.

Well, it was very low on coolant. Can't seem to see where it went. Filled up, attempted to bleed, don't see fluid leaking anywhere..

Hope its not a blow head gasket.

Cheap pressure test kit from harbor freight works on D2s and LR3s.

You will pressure test the cooling system at the expansion tank. 16 pounds and look for leaks/pressure to drop.

Oh, I though you meant test the cylinders to see if there is a leak down. Do you just pinch the overfill?

There is a cap adator in the kit that screws onto the overflow tank and has a fitting for the pump. Pump up to 16lbs and look for leaks.