Discovery 1 Overheating

[roverdevin]

Hey everyone...I have a troubling development with my discovery, and wondering if anyone can help...

Car:1998 Discovery 4.0L auto.

Symptoms:

Last 2 years...No cooling system problems at all...ran steady at operating temp with little fluctuation.

Last few weeks...I have been noticing the electric fans have been running on after I shut down the car, up to a few minutes even though the temp gauge is reading normal. It seemed to run on after shutting down regardless of how hot the air temperature was, or how hard/long the car was driven.

Today...Electric fans are not operating at all, even when running at temperature...and the car has begun overheating. It will run normally for a few minutes, but soon overheats quite quickly. I jumpered the electric fans directly to the battery, but this doesn't seem to help. The viscous fan seems to be turning, but I'm not sure how to check for proper function. It doesn't seem to be a qauge issue, as it is definitely running hot!

Also, a few quick questions....do the elec. fans run all the time when the engine is on, or are they intermittent depending on temperature? Does the engine usually run hot without these elec. fans, or am I looking at a blockage or an airlock? Any hints on diagnosing the water pump, or do these pumps fail often?

Thanks for any help! I'm getting a bit frustrated...I got this one because I needed a more "reliable" Land Rover!

Devin

[Rob]

Hi Devin

www.rangerovers.net has good information about rover V8s and cooling problems.

Regards, Rob

[PaulC]

Hi Devin
1-The electric fans don’t operate continuously, the electric fans are thermostatically controlled.

2- If your radiator is in good shape and none of the shrouds are missing or dislodged, I would first look at the fan’s viscous clutch.

Especially if you have jumped the electric fans and still had overheat condition, due to the fact that primary cooling is provided by the engine driven fan.

[chilliwack]

Is the top hose warming up?

Don't forget to check the thermostat before getting carried away on complex things

Cheers, Roger

[roverdevin]

Roger,

The top hose starts off empty (thermostat closed) then fills/warms up after operating temperature is reached, and gets very hot, which leads me to suspect that the thermostat is ok...unless it has partially failed, and is not opening enough? I will have the rad checked/flushed this week, but is there a simple check for the viscous fan coupling? It is spinning, but I'm beginning to think that could just be turning without locking up...

Any ideas on why the auxillary fans have stopped working? perhaps the temp/fan switch has failed?

Thanks everyone for your help,

Dev.

[roverdevin]

A bit of a development,


After reading the link that Rob sent me, i learned that Range Rovers can leak coolant from the heater into the passenger footwell. I have recently noticed dampness in my Disco passenger footwell...and I was down about a little less than a litre of coolant. I topped up the coolant and was fine for the drive from Vancouver to Squamish and around Squamish as well. I will have to investigate the stuff in the footwell. I just assumed is was rain leaking in.

The auxilliary fans seem to be working again...without jumpering. How often are these supposed to run? are they a "most of the time " or only under extreme work sort of deal? Mine are still running on after shutting down the car, even after a fairly short drive.

Dev.

[John]

As with any mechanical problem it is always a good idea to check the basics first. Checking coolant level is a good first step to diagnosing an overheating condition. I believe that the electric fans primary function is to provide cooling for the A/C condenser and as such they should be running anytime that you have the A/C turned on. As a secondary function they provide additional cooling when the engine powered viscous fan does not keep the coolant temperature below a specified temperature.

[roverdevin]

Well, I've had it in for a pressure test there doesn't seem to be any coolant leaking. I certainly don't lose much. I think I have narrowed it down to radiator flow or viscous fan.

Can anyone tell me how to test the fan? It spins freely when cold....and HOT! Does this indicate failure? (i.e should that be locked up when the engine is warm, or is spinning with my hand after a long drive not useful?)

It never overheats when driving around Squamish...there's just no traffic. Long drives are fine...it's when I hit Vancouver traffic that it gets going, and once hot, its hard to keep the temp down. Driving in low range with the heaters on full and keeping moving helps.

Thanks for any advice.

Devin

[DaveB]

I would take it by Don's or Alistair's shop in North Van next time you're there. It does sound like your fan may not be doing it's job, but they work on them every day so they'd know a lot more about it.

cheers, Dave