Alright Gents,

I have a 97' Disco 141K miles, that like everyone else, has overheating issues. Being a good disco owner, I've done a ton of reading and quite a bit of work on her but I still can't quite get my temps under control.

Some relevant bits I've replaced/tested:

• Upper and lower radiator hoses
• Water pump and front seal
• Viscous fan clutch
• Radiator - swapped with a nissens
• Heater hoses
• Water jacket on the throttle body heater thing
• Expansion tank cap
• Tested aux fans and even hardwired them to an extra switch for increased cooling without AC on
• Did a head gasket color change test, it was normal.
• Pressure tested the coolant system, it holds.
• Verified belt routing and swapped some bad bearings
• Running a 60% water, 40% coolant combo with a bottle of wetter water
• Changed the T-stat to a high flow 180 degree

And after all of that, I still am getting up to the 215-228 range after a 20 mile freeway drive in 40-70 mph traffic without the AC (if i hit 228, I pull over and wait for it to cool). I monitor temps with an OBD bluetooth adapter and the Torque app on my phone. I live in Utah, so the summer gets hot, but not like Arizona hot. The disco is running fairly rich, like LTFT -19, but I'm not sure if that is connected.

Any brilliant ideas from you Land Rover wizards? I'm officially out of good ones. The only options I have left are silly things like the coolant channels in my engine block are partially clogged..... Or there is a squirrel nest that is super insulating my engine (I don't have a squirrel problem).

Help?

 

That's a lot you did to try and combat the overheating.
I'm thinking simple for a D2 even thought yours is a D1 like check the fan? Check for broken/missing blades? Installed backwards/wires crossed? blowing air vs.drawing in air across radiator coils..

 

Is there no loss of coolant? Forgive my naivete, does the D1 have a vent tube from the top of the radiator to the overflow bottle, and if so, does coolant circulate?

 

What fuel temp are you seeing?

Could be a bad t-stat. It happens sometimes.

As you wrote, you have done a lot of the normally prescribed fixes, so some 'silly' questions need to be asked.

Not to insult you, but did you install the t-stat correctly? Spring side of the t-stat toward the block.

 

 

yup could be the stat, try pulling it and testing, and making sure the loop is bled fully

 

Thanks for the replies guys! Coolant is circulating, the D1 has a line that goes from the top corner of the rad to the expansion tank, I can tell that coolant is flowing. Not to mention, when I refilled the rad, I had the fill cap off and was running the engine (to heat it up and burp the system) and I could clearly see flow that was responding to RPM. I double checked the T stat today, and it is oriented correctly. I suppose the T stat could still be faulty though.

The fan blades are all unbroken and the fan is oriented the right way to move air through the rad.

How does one go about diagnosing/ fixing blocked coolant passages?

 

Also, ahab. No loss of coolant.

and Vanbadri, could it still be a head gasket problem even if I had a negative exhaust-gas-in-the-coolant test?

 

WaltNYC, I'm not seeing fuel temp on my list of sensors on my app. Im not sure if that means that my app isn't interpreting the data or if the sensor is bad. Any idea if there is a CEL that comes on if the sensor is bad?

 

Is your fan shroud present and intact?
When you apply throttle, do you hear a sound like water rushing behind your dash? (thinking maybe you have a nasty air pocket that won't go away)

Could it be that your temp sensor is faulty? Or wired incorrectly? (again, stupid questions but that is where we are).

Any chance you or someone around you has an IR thermometer with which you can verify the temps?