My 96 disco overheated today, and also seemed to have lost a little fluid. I checked for leaks, no dice, but I may have missed something. I also noticed that the large hose running to the top of the radiator wasn't pressurizing...... Any thoughts?

 

I realize its a bit vague, but I'm not sure where to to start let alone diagnose. Also I heard the fan running after I had turned the engine off........

 

1. Fan running is OK, it is designed to do that if engine is above a certain temp.

2. First we shall define "overheating". That would be above 50% on the gauge. To be sure of temps you need to use a scanner or ultra gauge plugged into the OBDII port.

3. You are far enough south that a 180F stat would work well, about $10 plus gasket. My D1 runs 178 - 183, maybe up to 187 at 70.

4. Coolant had to go somewhere.

External leak on to ground or burned off by engine parts while underway. Borrow pressure tester from parts store and pump up coolant to 15 PSI and let sit for an hour. Check for leaks.

External thru overflow for coolant container. Cap is supposed to hold until about 18 psi, could be bad. You can wrap paper towel around cap and end of any drain off hose to see if it gets wet with normal driving. Cap not too expensive.

Internal to oil - oil will look like milkshake, and increase on the dip stick. That is not normal for a Rover, usually they have no problem dropping the oil level on the dipstick.

Internal to cylinders - usually makes white smoke out the exhaust. Makes sound like bubbles running thru pipes under dash. That sound can be from air (leak) or exhaust gas (head gasket or cracked block). There is a $50 ish chemical test that chnages color when coolant has the exhaust gas in it. Kit does like 16 tests.

When coolant gets low, below the line in the pix, bad things happen. Heat stops. Coolant sensor and thermostat are exposed to steam, not hot water, so they don't respond as fast.

5. If radiator is gunked up with calcium, the fins on bottom will be more than 10F cooler than fins at top. This is a horizontal row radiator, and an old one could have calcium buildup. $600 radaitor - but you can find indy shops that will unsolder a side tank (brass and copper) and rod out the calcium, about $75 carry in near me. here is also an aluminum with plastic tanks aftermarket one that is on fleabay for about $235.

6. Hope your serpantine belt is correctly routed. Fan clutch should be checked, should feel stiff to turn when cold. When warmed up should be less stiff, but not freewheel.

What I am pointing out is that there are many causes of overheating, you need to resolve it quickly before any more damage.

 

ill make sure to start at the top and work my way through the list. The weird thing is, it happened randomly, and it seemed the fluid had broke. I let it cool, topped the resevoir off and it ran fine afterwards. Not sure if that narrows it down.

 

took it to advanced, error code p0125, it didnt overheat during the trip. ive looked on here and it seems it is either the ect sensor or t-stat. if its the sensor would the beast overheat?

 

No, the D1 uses two sensors, one for gauge (what you see) and one for computer (which you can see with a scanner). The gauge is not real precise, you may want to get a scanner reading of coolant temp. Yes, the sensor can be marginal or bad, and the conector or wires can have problems with grounding. You can clean up the cable conector, and some have even removed sensor and cleaned off the business end of it. They are not too expensive.

Put in a 180 F thermostat. About $10 plus gasket.