I was out for a drive today and noticed my rover overheating while waiting in the drive through, I turned it off for a while and hit the highway to go home.

It was over heating on the highway. So I got off let it sit and took some normal roads, no over heating. Went back on the highway, and it over heated again. Got off and it went back to normal.

I replaced the thermostat a few months ago along with the cap of the over flow tank and flushed the system out.

I'm trying to figure out what this issue is so I can get it fixed ASAP. Any ideas?

 

Fan clutch

 

I have never heard of that. How can I check it?

 

Def a air flow problem, fan clutch is where I would start.
If it overheated in the drive thru and you were only on the highway for a short time and the heat did not have enough time to dissipate it could overheat again.
Spin the clutch first thing in the morning, does it spin easy?
How about after the engine is fully warmed up?
If yes replace it.

 

Air flow problem or water pump not pumping (ie belt slipping)

 

Is the fan clutch easy to access and replace? Seems likely that this could be an issue.

 

I know you said you replaced the t stat already. however I was getting really hot only on the highway. as long as I was stop and go it would push enough water through the stuck stat to keep the engine cool as soon as I got on the highway it would run warm again, never over heat, but run hot. I would at least pull it off and check it. it wouldn't be unheard of to have one go bad.

if your running warm on the highway wouldn't the fan clutch irrelevant? wouldn't it either be the water pump, radiator or stat? if it were the fan clutch it would only run warm in a drive up or at idle. my money is on poor water circulation... stuck stat or partially clogged radiator.. the high rpms of stop and go keeps the water moving more.

when you say it is over heating do you have an UG or do you used the idiot stick on the dash? when mine was getting warm on the highway, I could put it in neutral and rev up the rpms and watch the temp drop on my UG... just my two cents..

 

Could be more than one thing. Fan clutch is easy to replace. Spin fan when cold, and release. Should feel like peanut butter inside, stop when released in a part of one revolution. When warmed up, repeat. Should still stop in under 1 revolution. One that freewheels won't do enough cooling at low speed.

At freeway speed running warm, goes away at lower speed. At freeway speed engine is working harder, fan is of little importance becasue of air flow. But if radiator is low on coolant and/or coolant passages are partially blocked, radiator can't dispose of heat quickly enough. A blocked radiator normally shows up as cooler on the bottom rows of fins than the top. Radiator flush does not do much for the system, the aluminum radiator has very small passages.

The Ultra Gauge or a scanner tell you exactly what the temp is. The factory temp gauge sits at 50% until overheating starts. Don't wait for it to rise all the way and think you are OK.

A new thermostat can be blocked with trash and cause overheating. A water pump can be on the way out and not pumping enough. A serpantine belt can be glazed or coated with something allowing it to slip and not turn pump properly.

 

This is definitly not fun.

When I woke up this morning, I got about a block and the red light came on above the temperature gauge, but the temperature gauge was at the bottom in the cold zone. The rover had only been on for about 2 minutes.

I came to a stop sign and the light went a way and the gauge moved up not even to the middle yet. After that the light never came on and the gauge never went above half for the rest of my 5km trip.

 

is your system full of coolant and proper bleed? I find it hard to believe that even a Disco II could over heat in 2-minutes from cold.