Thread: D2 radiator fan on - is this a symptom of doom?

Originally Posted by Trippy

Ah ok, didn't know the diesels were different. I saw it used in the video below (watch at 5:05). Not sure what year his car is but at the start of the video you can see that the headlights are from a D2a.

How To Change Land Rover Thermostat and Coolant - YouTube

The Scangauge uses the OBDII port as well right?

Yes scanguage uses the OBDII port. Year doesn't make any difference to OBDII support on the D2's. OBDII was a requirement for petrol vehicles from 1996 onwards hence the full support on the V8.

cheers
Paul

Bang on Paul. You're right I do have a TD5 (2002)

I may be wrong on this but Thinking about WHY fans remain on really hinges on the temperature of the engine when switched off and the "heat soak" developed.
The switch on a 14CUX petrol is set to trip at 102C and switch off at around 96C.
I expect that the ECU will do the same. If the sensor reports over say 102C then the fans will stay on.
SO IMHO your problem is that the engine is running too hot. Reason?

The most common reason is that the radiator is blocked. Distant second maybe faulty sensor. Another reason for overheating is the head gasket has failed but this should be accompanied by other problems like blowing out the water.
First step is new radiator at about $350. Experience on the forum is that cleaning will not work with an aluminium radiator and it will cost almost as much as a new one anyway.
BUT one thing is for sure it will not get better by itself.
Regard sPhilip A

On the Td5 the fan will run if the temp is 105°C with 10 seconds of switch off. The fan cuts out again when the temp drops below 100°C.

I agree that it's unlikely a head gasket. The engine is only likely to overheat as a result of loss of coolant resulting from a blown head gasket, so if the coolant levels look ok and you haven't been losing coolant that is unlikely be an issue.

As Philip suggests the cooling system is probably the culprit. You mentioned you were broke at the moment I'd suggest checking and testing the thermostat and temp sensor to make sure they are functioning correctly as a starting point.

The thermostat should fully open by 96°C so you can test by placing in boiling water and checking that it is opening fully. RAVE contains a chart of resistances and temperatures for the coolant sensor. You should be able to place the tip of the sensor into boiling water and check that resistance is correct.

A cheap multimeter with k probe would also give you the ability to check the temperature of the head and hoses when you stop after a run and give you an idea of what is going on.

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cheers
Paul

The sensor area will also heat up slightly when you turn the engine off as the viscous fan is not running anymore. I have watched on the Scanguage as the temperature increases by 2-4 degrees for a short time.
Now I have seen that on a warm day or after a "enthusiastic" drive that the temp can be up close to the sensor limit and then when I turn the vehicle off it goes over the limit and sets off the electric fans.

I think this is normal and a good thing.

But to be absolutely sure you need some kind of accurate water temp measurer.

Originally Posted by OffTrack

The engine is only likely to overheat as a result of loss of coolant

The same thing happened to me a few months ago. The fan was running for some time after switching off because the engine wasn't able to cool properly ... it was leaking coolant through the radiator.
Check your coolant levels, top them up with water (to begin with) and do a pressure test on the radiator. If all that checks out then it could be something more sinister.

Good Luck

Craig

walker,

perhaps if you have been working the engine hard that is true but as Wil said in the first post:

Etc but it hasn't been behaving like this until now, and the driving is very mild city driving in cool weather.

which does seem to point to something being amiss.

I know this doesn't help the OP since he has a Diesel, but I received the ELM327 this morning and tested it out on my 1999 D2 V8. It works great! I got it mostly because I was worried about the state of my cooling system but the engine coolant temp sits at 85 degrees when driving and 88 degrees when idling (ambient temp of 25 degrees today). Those are good temps right?