Help - V8 overheating on the sand!

[Tyresqueal]

Hi All,

Every time I take to the beach, my D1 V8 starts to overheat – not good as a 10 minute drive turns into a 2 hour start/stop/cool drama. I have now stopped going onto the beach and have started to do some diagnostic work.

At first I thought that the thermo fan wasn’t working, but it seems to be spinning fine and trying to stop it with a large screwdriver doesn’t work – ouch!

Next, I checked the two electric fans and this has left me seriously puzzled. The near/passenger side fan seems to come on when I first start the engine from cold, but then stops soon after – it also looks like it isn’t spinning at full speed. The off/driver side fan doesn’t come on at all.

I read in another thread that the switch on the thermostat housing controls these fans and that bridging the switch should turn on the electric fans – not in my disco.

I then decided to check each fan with a direct live/earth wiring from the battery and neither fan rotated – I read that the direction of rotation depends upon the polarity, so wasn’t too concerned with which way round my connections were – will try different combinations tonight.

Please, please help as I’m now going mad – how can one fan work when cold and then neither fan work when connected to a direct power feed????

I should also probably mention that my A/C doesn’t work either, so could this be a contributing factor to their lack of movement when the engine gets too hot.

If anyone can educate me on how these fans operate and how I can test them etc. then please share before I light a rag in the fuel filler neck and run away!

[V8Landy]

I'm pretty sure that the thermos are for the air con only unless been altered sounds like one motor might be Knackered as the other one works(May be on a thermo stat to come on at a higher temp).Check your thermostat is opening as this will cause it to over heat but should do so in traffic not just on the beach.Radiator could need a clean or maybe(i hope not)your headgasket is going or a minor crack or something opens up under heavy loads.As always check the simple things first(water level)and go from there.hope this helps someone will have a better idea than me but it's a start.Cheers Brett

[RonMcGr]

Wrong way to check the fan hub :eek:

When you start the vehicle that fan should normally roar for a minute or so then stop.
When the vehicle temperature gets to half way up the dial, that fan should be making a load roar and sucking air through the radiator.

If it is not doing this, it's stuffed.

The twin electrics work with the air-condioner to cool the condensor.


Ron M

[Utemad]

I don't know what your particular problem is but the aircon fans also come on when your engine temp gets too hot. They will even stay on for a certain period of time after the engine is switched off if required.

The RAVE cd explains how it works.

That is for the update D1 anyway. What year is yours?

[streaky]

As others as said...the twin fans up front are for the a/c condensor.

If sand driving is causing the over heating problem than you are probably not getting enought flow through the radiator. Sand driving puts more strain on the engine than any other form of off roading...it literally saps the power out of the engine and you're oblidged to plant the right foot even more.

Get the rad flushed, replaced or re-cored. Use water wetter if you can find some.

Make sure that the fan shroud is correctly fitted...no big gaps down the sides etc.

Check the top and bottom hoses arn't collapsing under load also. If the thermostate is working them leave it in. Others have mentioned how to check the viscous fan...thats good advice.
Does the engine start pinking when under load? Thats also a contributor to over heating...not severe but it's worth getting the timing spot on.

I'd put my money on it being a radiator flow issue. Sand driving is what we do every weekend and I've learn't quite a bit on how to prepare my V8's for it.

Further down the road of investigation you may want to drop the water pump off. Corroded water galleries around the impellar can cause cavitation and poor circulation issues.

Good luck.

[Utemad]

Do you let your tyres down or flog it mercilessly at highway pressures?

Just a thought.

[PhilipA]

KISS
First thing to do is have the radiator dismantled and cleaned ( do not think that filling it with caustic soda or many other fixes will work. They will not) . Odds are you will have to replace the core for about $600 so be prepared.
If that doesn't fix it then you look deeper, but cross that bridge when you come to it.
Re the aircon fans. At first start up while the viscous is roaring, it is pulling a lot of air and may turn the aircon fans. The aircon fans move all the time at highway speed even if off , its just that you don't notice because if you are close enough to see , you will soon be run over.
Regards Philip A

[RonMcGr]

The aircon fans move all the time at highway speed even if off , its just that you don't notice because if you are close enough to see , you will soon be run over.
Regards Philip A

LOL :D
Bit like aircraft cruising in the sky, that beater turns the motor over even when it's switched off!

[rovercare]

The front thermo's switch on the thermostat housing only operates at 100*C and is only back up, will also operate with ignition off at these temps

Your method to check the fan hub is crud, you can use your hand or simply check straight after you've switched off, "listening for a roar" isn't accurate;)

I'd do as PhillipA suggests first:)

[Tyresqueal]

Thanks for all the feedback and can add some additional info.

The thermo fan constantly roars, so suspect it is okay and this is probably what is turning the rogue electric fan. The engine temp doesn't budge even a millimetre on the guage when left on idle - so this would also indicate to me that the thermo coupling is okay.

There seems to be a contradictory view on the electric fans though. I was under the impression that these were primarily for the a/c, but are also supposed to cut in when the engine reaches about 95 degrees - as a secondary cooling support. My fans don't come on at all - even when the engine temp guage was up in the red and also when I bridged the switch. Any suggestions on testing these?

It's a late '94 build and '95 registered model.

I ALWAYS drop my tyre pressures to 16psi for sand work.

Given the advice provided, I guess that it's probably radiator flow that's causing the issue then. I'll also have a look at the water pump and pop in a new thermostat whilst I've got the system drained.

[RonMcGr]

Thanks for all the feedback and can add some additional info.

The thermo fan constantly roars, so suspect it is okay and this is probably what is turning the rogue electric fan. The engine temp doesn't budge even a millimetre on the guage when left on idle - so this would also indicate to me that the thermo coupling is okay.

There seems to be a contradictory view on the electric fans though. I was under the impression that these were primarily for the a/c, but are also supposed to cut in when the engine reaches about 95 degrees - as a secondary cooling support. My fans don't come on at all - even when the engine temp guage was up in the red and also when I bridged the switch. Any suggestions on testing these?

It's a late '94 build and '95 registered model.

I ALWAYS drop my tyre pressures to 16psi for sand work.

Given the advice provided, I guess that it's probably radiator flow that's causing the issue then. I'll also have a look at the water pump and pop in a new thermostat whilst I've got the system drained.

In that case, definitely Radiator.

Do what PhilipA says and get it professionally cleaned.

Ron M

[maggsie]

I have just gone through the same exercise, my County was getting rather warm while sand driving. I had the radiator cleaned and 10% of the core had to be blocked off due to its poor condition.It still wasn't satisfactory so I bought a complete new radiator from Rovacraft and put Davies Craig thermo switch on my electric fans and the problem is solved. Rovacraft normally sell the new radiators for @ $350.00, a lot cheaper than the $480.00 I was quoted for just a core.

Regards
Maggsie

[PhilipA]

It sounds like you may also have an issue with the fans or the fan circuit.

First place a multimeter on the power side of the fan switch . You should have 12V. If you have 12v , then bridge the switch. If the fans do not work you need new fans or the earth from the fans is crook. If the fans work by bridging the switch the switch is crook.

If no 12v then work back through the relay and fuse to find the open circuit.
Without looking at the circuit, there must be 2 power feeds, one through the thermo switch for overheat and one through the aircon switch. Try the overheat circuit first as it will tell you whether its fans or power.
OK I looked at the circuit. there are two separate relays, the aircon/heating relay, and a specific relay for the fans. the fans share earth with the compressor clutch, so if the clutch works then the fans earth should be OK , but check anyway.
To check the fans you can also just hot wire them from the battery with a length of wire.
Regard s Philip A

[stevejo43]

Get yourself some of those Staun deflators. They work a treat and preset them at 11 - 12 psi. and watch your 4wd laugh at that soft sand. It probably is a good idea to get your core rodded out i have had a few cars with this prob and all overheat past 100 kmh too. But do try 12 psi on the sand. I have found it makes a lot of difference to the 15 - 16 psi that my friends told me they used and a lot less hard work on the engine too

[Tyresqueal]

It sounds like you may also have an issue with the fans or the fan circuit.

First place a multimeter on the power side of the fan switch . You should have 12V. If you have 12v , then bridge the switch. If the fans do not work you need new fans or the earth from the fans is crook. If the fans work by bridging the switch the switch is crook.

If no 12v then work back through the relay and fuse to find the open circuit.
Without looking at the circuit, there must be 2 power feeds, one through the thermo switch for overheat and one through the aircon switch. Try the overheat circuit first as it will tell you whether its fans or power.
OK I looked at the circuit. there are two separate relays, the aircon/heating relay, and a specific relay for the fans. the fans share earth with the compressor clutch, so if the clutch works then the fans earth should be OK , but check anyway.
To check the fans you can also just hot wire them from the battery with a length of wire.
Regard s Philip A

Thanks Philip - I'll check the overheat circuit 1st as I know the aircon is crook. Think I'll get on and order a Rave CD for this as the Haynes manual isn't so clever with wiring diagrams.

I did try a hot wire from the battery (+ve and -ve wires) and neither fan worked, so it looks like several issues which is why I've been pulling my hair out. It's nice to know that I'm on the right track though.

[Tyresqueal]

I have just gone through the same exercise, my County was getting rather warm while sand driving. I had the radiator cleaned and 10% of the core had to be blocked off due to its poor condition.It still wasn't satisfactory so I bought a complete new radiator from Rovacraft and put Davies Craig thermo switch on my electric fans and the problem is solved. Rovacraft normally sell the new radiators for @ $350.00, a lot cheaper than the $480.00 I was quoted for just a core.

Regards
Maggsie

Thanks Maggsie, this sounds like the best option - cheap and you can't beat a new item. I'll give Rovacraft a bell.

[Tyresqueal]

Get yourself some of those Staun deflators. They work a treat and preset them at 11 - 12 psi. and watch your 4wd laugh at that soft sand. It probably is a good idea to get your core rodded out i have had a few cars with this prob and all overheat past 100 kmh too. But do try 12 psi on the sand. I have found it makes a lot of difference to the 15 - 16 psi that my friends told me they used and a lot less hard work on the engine too

Will give this a try, but was always worried that I'd break the bead at such low pressures without locks fitted. Will take you at your word and hunt you down if I blow it :D

[foz.in.oz]

Please be cautious if you do drop your tyre pressures as low as 12 psi. There are issues associated with lowered tyre pressures other than bead breakage. If you lower your pressures you must restrict your top speed possibly to as low as 40kmh max as under inflated tyres generate shed loads of heat and can break down/self destruct with catastrophic results. Land Rover recommend a minimum of 16psi and also recommend restricted top speed. Don't trade off safety for flotation:)

[100I]

I'm with Foz.
I usually run about 18-20 on the beach and dry sand tracks and have never had an issue (and I am a strong advocate of low pressures as soon as leaving the tar), 16 would be ok, but Í've never found anything in Qld that needed it. The dry dunes of places like Stockton may be very different though.
I've been to 8 in Suzukis but they are a far far lighter car.

[Tombie]

I'm with Foz.
I usually run about 18-20 on the beach and dry sand tracks and have never had an issue (and I am a strong advocate of low pressures as soon as leaving the tar), 16 would be ok, but Í've never found anything in Qld that needed it. The dry dunes of places like Stockton may be very different though.
I've been to 8 in Suzukis but they are a far far lighter car.

I agree....

In 20 years of driving I've only once needed to drop below 16psi...

And that was in powder.....

12 is too low for %99.9 of all offroading exceptions being Simex tyres etc...

[Aaron IIA]

Last time I went to the sand I got hold of some "new" second hand 31x11.50x15 tyres to fit to my SIIA diesel. As you may know, these engines do not produce bucket loads of power, so I needed maximum flotation. I let the tyres right down, then inflated them just enough to get the buckle out. It turned out this was about 5~6 PSI, and provided a vast improvement of the drivability in the soft sand. I am not reccomending this for everybody, but it did help a lot in my case. I did not get above 20mph at any stage, and as the tyres were second hand, their longevity was not my main concern. No damage was evident to the tyres At the end of the day, I fitted my standard 7.50x16 to drive home.
Aaron.

[V8Landy]

I did try a hot wire from the battery (+ve and -ve wires) and neither fan worked, so it looks like several issues which is why I've been pulling my hair out. It's nice to know that I'm on the right track though.[/quote]

If your thermos arnt working pull them off and get a motor out and go to the wreckers to see if you can find some thermo fans with the same shape & pattern screw holes.Test they turn the right way.Heaps cheaper than buying knew.I was qouted $600 to $700 and fixed them for about $30.Cheers Brett
P.s Alternatively i have a set from a 92 disco you could buy:D:D:D

[stevejo43]

Have never popped a bead yet. My friend did ask could he try the staun deflators on his heavier 80 series Landcruiser, he also never popped a bead and neither of us had bead locks either. Staun make bead locks for the purposes of going under 10 psi on sand however, I'm not sure about the heat factor on the tyres and whether this product would prevent that or not. We drove the length of Stockton beach and back to Lavis Lane. (a part of Stockton beach entry that no one seems to like because of soft choppy sand) Both vehicles did it easy and experienced no dramas. I do average about 40-50 k's, Go to Stockton often and don't drive close to the water although my friend does. I think the slope factor there might have potential to perhaps bring you unstuck in some way (soft sand unexpectedly at high speed or bead pop there would probably be disasterous) I'd probably say though if you're in the habit of driving close to the water and say over 50-60k's maybe better to stay with 15-16psi