Hello, wondering if anyone else has also experienced their disco overheating only when driving in stop/start traffic conditions. I live kind of inner city so I'm always sitting in traffic before hitting the highway. In traffic it starts to climb all the way up to red on the thermostat and can physically feel it getting hotter but as soon as i get to the highway it starts descending and cooling down. Why might this be? Radiator fan seems fine, A/C works great, coolant level is fine with no signs of air or bubbling in the system. Any help would be greatly appreciated.

 

Mine was doing this and it was a combination of the water pump was on its way out, and the fan clutch wasn't engaging properly. When you're driving at highway speeds air is forced over the radiator and over the engine itself effectively helping to air cool it but the second you stop and its entirely reliant on the fan/pump it takes a harsh dive. I would make a solid effort to diagnose these two areas before continuing to drive as overheating is a big no no on these rigs. My fan clutch was passing the hand turning tests but when I pulled it out almost all of the "gel" Inside it was leaked out onto the outside. Replacing it first helped with my overheating some but didn't fully nix the problem until I pulled the water pump. Neither are particularly hard jobs. I go pretty much all the procedures to do both from reading several older forums. This website has tons of knowledge wrapped up in it. As I always say I'm sure someone far more experienced than I will chime in soon! It's a great resource! Happy trails!

 

I also live in a city, and am familiar with the issue. When I had my same issue, it was that the electric fans on the front grill condenser intake were not operating. Apparently a 98 D1 has two sets of fans that work to push air past the radiator, they’re basically always on when the vehicle is. Once the electric fan unit was replaced, I was back to normal.

Here is another post the better details the issues: https://landroverforums.com/forum/discovery-i-39/d1-condenser-fan-motors-replacement-43633/

 

You've got a few things to check:

• Radiator: even if it looks good, it doesn't mean its running efficiently. I thought mine looked great until I pulled it and found several hidden wasp nests on the side facing the condenser fans, along with tons of leaves on the bottom 1/4. I would evaluate both sides carefully.
• Water Pump: this has been covered above. Relatively easily to swap. I have a Flowcooler and happy with it, but can't say that it's much better than an OEM unit.
• Condenser Fans: these actually only turn on when your AC is on or when your coolant hits a certain temperature - they're not always on. Simple test: turn on the AC and check to see if both are moving.
• Fan Clutch: when you move the fan, does it move freely when cold or does it have a lot of friction? If it moves freely, you need to replace it.
• Thermostat: while likely not the issue here, i'd inspect / replace if you're going to dive into the cooling system. Its simple to do and sold T-stats can stick.

 

Liam, your symptoms are typical of a fan clutch failure. If the goo has leaked out, they don't work anymore to engage the fan when slow or no vehicle speed. There are threads about what model other folks like on the forum.

 

The fan clutch also has a thermostatically operated lock up - once the bi-metal spring on the front gets hot enough, it should expand and cause the internal clutch to engage, speeding up the fan. Make sure the fan clutch is clean... but it sounds like it's dead.

 

My electric fans weren't engaging so I just wired them to a separate switch, when it is hot and I see the temp going up on my obd2 display, I flick the switch and keeps the temp from going too high.

I do need to have the rad cleaned, or the main fan as well, but it keeps it cool until I have time.

No need to worry where I am in the winter as I can't get it to warm up past 160,.I need to check thermostat too.