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Discussion Starter · #1 ·
I set off yesterday on the hottest day of the year 26C. After about 10-15 miles the temperature gauge started to go past normal vertical up to temperature position. After another 5 miles the red temperature warning light came on. I turned around & drove back home. I assumed that the hottest day of the year plus not checking coolant level probably meant I was low on coolant but I check after it had cooled down & there was no coolant missing. I tried driving again & after about 5 miles the red light was on again.

The car is a 2000 V8 4.6L Vogue. The cooling system was worked on last year after the water pump sprang a leak causing loss of coolant. Exhaust gases were entering the coolant so as a last cheap desperate measure Steel Seal was used which fixed any & all leaks & seems to have fixed the head gasket without removing the head. I suspect that the heater matrix is now gunged up with Steel Seal as while the heater still works it's impossible to get the heater output really hot as was possible previously.

I assume that it's the thermostat that has stuck but could it bee anything else? Is there a simple way of checking? Is there a simple way of fixing it? As it happens I have the car booked in to the garage next week as I have had the EAS fault come up a few times recently & it's taking minutes to pump up the suspension after sitting overnight so I can get them to look at the thermostat too.
 

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Steel Seal is water glass (Sodium Silicate) so only solidifies when it reaches combustion temperatures so shouldn't have clogged the heater core, but taking the two hoses off at the bulkhead and reverse flushing it with a hosepipe will probably shift some muck. If the heater core is clogged then chances are the radiator is too so that might be improved with a back flush too although replacement is the only proper option. If the thermostat had failed shut then it wouldn't take 5 miles to get hot, more like 5 minutes, so that is unlikely.

The EAS fault is a leak or leaks combined with a worn out compressor. It shouldn't take minutes to pump up after being left overnight as it shouldn't drop in the first place. Even if you deliberately cause it to drop, it should come back up immediately the engine is started, no more than 10 seconds. My spare P38 hasn't been used for two weeks now and is still sitting at normal height although my everyday one never gets chance to drop as it is used virtually every day.
 

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I do hope you didn't drive it back while the temperature warning light was on!
It does sound like something is clogged, very likely if Steel Seal or similar has been used. Or just through age and wear. If you remove the fan, you can check the temperature of the radiator, it should be considerably warmer at the inlet than at the outlet. Thermostat can be removed (not the easiest of jobs) and tested withh boiling water instead of just replacing.
 

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2002-2005 Range Rover MkIII / L322
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These engines should never be driven if hot, there is every likelihood you will cause problems.

(26 deg C isn't very warm, sounds like a spring or autumn day. 48 deg C is a hot day.)

294552
 

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1995-2002 Range Rover P38A
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That wasn’t today! At least when I went through Emu Plains! :)
 

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Discussion Starter · #6 ·
26C is warm for the UK. I did drive it home with the red light on. The needle on the gauge didn't go off the scale & when I checked the coolant level after it had cooled down no coolant had been lost. My conclusion was that it had only been marginally over temperature.

I already have it booked into my local 4x4 specialist next week to sort out the EAS issue so I will get them to look at the cooling system at the same time. Perhaps it is due a new radiator & heater core? In two weeks it is the 20th anniversary of the car being first registered.
 

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I hope you get away with it... If the red light comes on, you should stop as soon as possible/safe and let the engine cool. It really is the final warning, good practice would be to stop before the needle reaches the red or the light comes on.
The heater core will have nothing to do with the overheating, the only time that can cause overheating is if it leaks bad enough to lose a lot of coolant. But you said the level was fine. Which is strange for a car drive with the engine overheating. Normally the excess heat will cause a rise in pressure and the coolant cap will vent to prevent something else blows under the pressure. Was there any pressure still in the system when you opened the cap?
 

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It is just a possibility but worth a check. Before your mechanic rips everything apart get them to check the true temperature with a IR heat gun. The best place is the steel pipes between the pump and the bulkhead. I recommend this because my 1996 was going red-line on the gauge when I bought it 2 years ago. I was told to check it with an IR gun - the gun said approx 87 degrees in the steel pipes. I got my faultmate re-registered for my new car and it also said that there was no overheating - 91 degrees. Somebnody on here suggested that I clean all the earth points and - voila - no more gauge false readings. I cleaned the 2 earths on the RH guard and also the gauge earth point behind the RH side kink plate.
This is just a possibility - get them to use an IR gun first.
 

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Or plug an OBD reader in and read the coolant temperature. The temperature sensor on a Thor is two sensors in one housing, one feeds the gauge, the other feeds the engine ECU. An OBD reader will show the temperature the engine ECU is seeing.
 

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The EAS issue will be a worn out EAS compressor piston seal. These are essentially a consumable. You get ~4-5 years from one, less if you have air leaks.

No HOT air from the HEVAC, will most likely be stuck/fouled flaps in the airbox. The 'blend motors' don't have the power to move all the crud out of the way at the end of flap travel. There is a way to force the flaps to move to full extend of travel - let me know if you need instructions.

The engine overheating issue, is most likely to be caused by a failed/failing viscous fan drive unit. These are easy to diagnose at startup, as you should get an intense roar from the cooling fan, for up-to a minute or so - if you don't, then the viscous fan unit is bad. Fortunately, these viscous fan drives can easily be fixed (by adding new fluid) - check out this video:
 

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Discussion Starter · #11 ·
The EAS issue will be a worn out EAS compressor piston seal. These are essentially a consumable. You get ~4-5 years from one, less if you have air leaks.

No HOT air from the HEVAC, will most likely be stuck/fouled flaps in the airbox. The 'blend motors' don't have the power to move all the crud out of the way at the end of flap travel. There is a way to force the flaps to move to full extend of travel - let me know if you need instructions.

The engine overheating issue, is most likely to be caused by a failed/failing viscous fan drive unit. These are easy to diagnose at startup, as you should get an intense roar from the cooling fan, for up-to a minute or so - if you don't, then the viscous fan unit is bad. Fortunately, these viscous fan drives can easily be fixed (by adding new fluid) - check out this video:
Thanks for the suggestions. I have owned the car for 10 years & twice during that time have had stuck blend motors that made it impossible to switch the heater off. In one case as I recall the whole dashboard had to be removed to fix the problem. If there is any easier way to unstick blend motors I would love to hear of it.

Last year it had first the rear air springs replaced & later the front. I should have asked the garage to replace the EAS compressor at the same time.

It's in the garage at the moment. It was out for a test run when I called up yesterday evening. When I took the car in they quite rightly pointed out that it wasn't worth looking at the EAS (or recharging the A/C) until the overheating issue was sorted. I will keep this thread updated. Fingers crossed all is well as we are due to go on holiday tomorrow.
 

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The RHS blend and distribution motor are easy to get to if you remove the instrument binnacle. The LHS blend motor can be accessed by removing the glove box.

I find it useful to run the distribution motor through its full range (vents to screen and back) every couple of days to keep things free and moving.
 

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Discussion Starter · #14 · (Edited)
I have the car back & it's mostly OK. Yesterday with some trepidation I drove about 500 miles from Essex to Brittany via Eurotunnel mostly over 70mph & all without a problem.

The overheating appears fixed. The garage tell me they used a heat gun & there were no cold spots on the radiator but the cooling system was over-pressured which they diagnosed as combustion gases entering the cooling system They flushed the system & added two more bottles of Steel Seal. It's now operating at normal pressure & not losing coolant plus the needle on the temperature gauge never rose above normal.

The air conditioning is once again ice cold. I've owned the car for ten years & have needed to recharge a/c almost every year. I had the system serviced by a specialist a/c engineer about 5 years ago. If the price of keeping the a/c running is £40-50 to recharge it every year I'm not complaining.

The heater is still producing very little heat. It's warm OK but it used to be absolutely roasting if you turned it up to max. Not such a big deal at this time of the year of course but it does pint to a problem somewhere. The garage mentioned leaking heater O rings as there was some leaking in the driver footwell.

I'm less happy with the EAS. It still loses height overnight & takes a couple of minutes for the dashboard light to stop flashing. Even stopping briefly eg when refuelling I get the dashboard light flashing for 30 seconds. It also has a tendency to do the little front end dance while stationary with the engine running. They replaced the compressor but couldn't find any leaks so suggested it might be the valve block.

I think that I'm going to take it to another garage when I get back to the UK. Does anyone have recommendations for a specialist in North Essex / South Suffolk?
 

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If it's never been done, the valve block will almost certainly need new O rings. A set of O rings is cheap enough and how to do it yourself is well documented (EAS Valve Block Rebuild Guide | PaulP38A.com). Hopefully you have some sort of diagnostics or an emergency bypass kit with in . If the EAS ECU thinks it takes too long to rise it will go into fault and you'll have no suspension. I've got a Nanocom which lives in the car but also carry a set of these RANGE ROVER P38 EAS AIR SUSPENSION PUMP INFLATION BYPASS VALVES ANR3731 **6mm** | eBay so I can blow up the suspension with a tyre pump if I am stuck hundreds of miles from home. Heater core O rings are another service item about every 15 years so it they haven't been done they should be asap.
 

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Discussion Starter · #16 · (Edited)
I am now travelling with a laptop & lead so that I can use the EAS Unlock software if I encounter an EAS fault. I have a iCarSoft CR Pro that I got to use with my Jaguar S-type. It's supposed to support the Range Rover too but doesn't seem to do anything very useful. It can read & clear a few error codes but nothing regarding the EAS.

I stopped doing DIY car servicing & repairs about 30 years ago. I find for pretty much anything beyond changing a bulb or checking fluids levels that it's better for me to use the time I would have spent working on the car earning money to pay someone with experience to do it for me.😀
 
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