I have a 98 Disco I and have replaced the water pump and fan clutch in an attempt to fix an overheating problem. Although there were some issues that these new parts corrected, I now have the gauge stating the the land rover is running hot after 15-20 minutes of driving, but the shop where I have been taking it to has done a compression test as well as many other tests, and they have determined that although it states an overheating state, it is not actually running hot!


Must be an electrical problem but can anyone tell me where to start on this? I have already tried cleaning the contacts on the gauges with no success.

 

Have you tried hooking it to a live data scanner to get actual temp readings? If the live data temp is in proper range then I would guess its a faulty gauge sensor or faulty gauge.

 

D1 has two heat sensors located on the driver's side of the thermostat housing where upper hose attaches. They are vertical stubs, one sensor has two wires - it drives the ECU for the live data. The other is a single wire unit. That drives the guage. When engine is "cold" in the morning before cranking, and key is on, does guage rise up to some reading? Normally it would not, unless you had a skinned wire, ground, etc, You can remove the wire from the single wire sensor once truck is warmed up. The sensor itself is a brass rod that is threaded. It can be screwed out with minimal loss of coolant when cold. Sometimes they build up scale and read lower than normal and can be cleaned with a wire brush, but false overheat indication you would want to change it.

Another way to double check sensor vs reality is to use an IR thermometer, point it at several spots, like the sensor mount, the thermostat housing, the radiator just around the corner from the top hose inlet, etc. But those will NOT be as accurate as the scan data from the second sensor two inches away from the guage sensor.

Check belt route. You will find a link to it in our tech section for D1. If WP was changed, belt could be wrong. Why Rover does not spend 25 cents for a sticker to go on the top of the radiator with diagram is unknown. I am tempted to print one out and tape it there covered with clear shipping tape. See http://api.viglink.com/api/click?for...13149642031281 for belt route diagram.


Check fan blade on correctly, cupped side toward engine.

The radiator being plugged up can make you run hot, and it can cool off the air going to the viscous fan clutch, keeping it from fully engaging and making things worse at slow speeds. If you are still overheating at roadway speeds, look at radiator, trash between radiator and condenser, fan blade on backwards (cupped side goes toward engine block). If no coolant loss, pressure test OK, no Tick, perhaps the dreaded slipped liner has not happened. If overheating at low speeds or idle, look at radiator, trash in front of radiator, electric cooling fans for AC going in correct direction (test by switch on ignition, but don't crank. Turn on AC, which makes electric fans come on. Hold wimpy plastic bag near grille - it should pull toward truck, not blow outward - a PO wired mine backwards!).

Many owners have the radiator flushed and rodded out at indy radiator shops, if you carry it in the price seems to run $50 - $75, if it is not falling apart. This removes a great deal of the calcium buildup that happens from using hard water, instead of distilled water. Well water is the worst.

There is a coolant additive you can buy at most parts stores called wetter water, and it will drop temps several degrees, sometime up to 20. It does work, and racers use it because they can't use antifreeze at the track (too slippery after a crash or leak).