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Discussion Starter #1
Just curious, what is the normal operational temp supposed to be?

I just decided to log that in real time with a scanner and I'm getting 220... Is that normal?

Thanks
 

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If anyone is interested I have had my electronic thermostat wired to ground for 3 years to lower engine temp, to help with a head gasket leak that I had. My car is currently in having a new timing chain & tensioners etc so am having the head gaskets done at the same time & when it returns I will be wiring the thermostat to ground again so that it runs at 90 degrees to take the strain off the engine.

You can find out what temp your RR is running at before and after by accessing the info in the hidden screen. please find attached link:-

http://www.roverupgrades.com/Range_Rove ... menus.html

There has been interesting posts regarding cycling heat changes when messing with the thermastat but I really don't think this is an issue as you can't get any more of a cycle from when the car is cold in the morning to it's normal operating temp and back down again which is done reguarly. It is my belief that the extra temp is indeed to help with the emissions CO2 but this is not an issue on my used car and since I did the mod years ago I snoticed no difference in MPG.

Running the car at 90 degrees is far less strain than 110 degrees as designed but saying that the car should be able to run as per design but my car is getting tired 106K on clock and want to help her run as easy as possible for as long as possible. At the end of the day there isn't very many cars which have this electronic thermostat which assists the mechanical one which is in place. These RR are cable of running in all kinds of hot conditions in the Sahara dessert etc and so the cooling capacity is large, I just select to use it to the max for mechanical sympethy. The car still warms up the same because the thermostat is still present and the electronic one (coil in wax) only assists it's action.

The other reason I do this, is because my car runs on LPG which makes the car run a few degrees hotter and believe this can force any issues or weaknesses your engine may have from previous owners cooking of engines.

I hope this info help..................Adam
 

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I'm not so sure this is a good idea. Probably would lead to power and fuel efficiency loss, or other problems. The hotter the head and piston are, the less heat is conducted away from the burning and post-burn gases, the hotter the gases stay, the hotter they stay, the higher the pressure goes/stays, this pressure on the top of the piston is what makes it go. Many modern cars with high compression engines (which say you need premium fuel like our RR) run at 220 - 230 degrees.
 

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2002-2005 Range Rover MkIII / L322
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linuxfreakus said:
I'm not so sure this is a good idea. Probably would lead to power and fuel efficiency loss, or other problems. The hotter the head and piston are, the less heat is conducted away from the burning and post-burn gases, the hotter the gases stay, the hotter they stay, the higher the pressure goes/stays, this pressure on the top of the piston is what makes it go. Many modern cars with high compression engines (which say you need premium fuel like our RR) run at 220 - 230 degrees.
I agree, this will also lead to slight overfuelling, which in turn will shorten the life of the cats (x4) You'd be much better just making sure your cooling system is in A1 condition.

Just my opinion of course.

Dan
 

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I hear the concerns, but one thought is that when over fueling occurs (which I would guess will be a very slight amount of over fueling) and the 02 sensors read an increase in emissions, then the ECU should be able to trim BACK the fuel delivery through injector pulse shortening to make the emissions readings happy again!

I think this higher heat generation setup is to maximize fuel economy, perhaps at the cost of engine longevity. This fuel economy maximizaiton is probably driven by CAFE requirements and LR was trying to eeek out the last bit of economy. It's interesting to note that the BMW 540i and 740i of this vintage do NOT have this pre-heated thermostat. I would surmise it's because those cars are 1000lbs less than a Range Rover and didn't suffer the weight penalty reduction in MPG.

Thoughts?
 

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Yeah, probably true... similar to the argument we had a while back regarding effects of CAI if you are only doing normal driving. I still don't recommend messing with the designed temperature though.
 

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i checked my 06 ML500 this weekend and it settles in right at 90C even in the Florida heat... thats quite a bit cooler than the 117C the 4.4 is running at...

I guess i just have to assume BMW knows more than me... I guess i have always been under the illusion heat kills motors and gear boxes :(
 

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Discussion Starter #13
I'd agree the higher temp is probably beneficial to the motor in terms with how it's designed to run (5 series BMW) but in a range rover, the temp it runs at is more than the cooling system can deal with IMO. Low t-stat might be the lesser of the two evils. I'm sure we can all agree the cooling system in the range rover is doomed right out of the gate. Every bmw quick disconnect is a time bomb, the res is know for exploding, the rad will fail at some point, trans coolers fail with trans overheat message, the list goes on and on. I plan on tripping the t-stat to open next time I'm under the hood.

Too bad this isn't a mustang, lol... I run a cooler stat on my mustang, but it's easy to get into the fuel tables, change timing, etc etc. I wouldn't know where to begin on the RR, but it does seem like it should run cooler.
 

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I am a little confused by this statement as i want to do this mod:

Put it all back together, the only way you can now check how hot your engine is running, is by sticking it on the diagnostic machine
What does this mean specifically? Will the temperature gauge go up indicating a pending overheat and can one still read the coolant temp from the hidden menu or does doing this mod remove the ability to read the temp from the hidden menu?

Thanks - great info.

JH
 

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At the time of writing the origonal post over on www.landyzone.co.uk, I didn't have access to the hidden menu. Which I only found the hidden menu a few months ago.

So as a test if you access your menu now, before the modification, you should notice a temp around 104 degrees normal running, not in traffic. You will not notice any difference on the dashboard temp guage as this is not accurate at all.

Then carry out the Mod, run the car up (take it for a drive) and access the hidden menu and you will prob get a temp of around 90 - 94 degrees.

So doing this mod doesn't effect the hidden access menu, you are just using this menu to confirm the effect of the mod.

......................Adam
 

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soo... I did this mod and the engine temp did not change at all. I cut and grounded the brown/white wire FROM the thermostat. Left the side that runs to the ecu as open - just put an end cap on it. Verified i get 12v dc when key is on at the plug as well as multimetered the ground. I do have pics, but i want to be sure i have done this properly first before i post.

My question is - does this mean that my thermostat is bad? Or did i wire it up wrong? I see +12v at the plug with power on - placing - on the brown white and + on the blue wire.

I have been told 2 stories on what the wires that run into the thermostat on these do:

1 - it is just used to read the temperature at the thermostat.
2 - it is a "heating element" made to heat the thermostat area so it opens faster.

I find both of these to be a little silly... I would assume it is:

3 - some sort of tension control on the thermostat so it opens some or all the way.

Any help on this one? Did i wire it wrong or do i need a new thermostat?

JH
 

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2002-2005 Range Rover MkIII / L322
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jhepworth said:
I have been told 2 stories on what the wires that run into the thermostat on these do:

1 - it is just used to read the temperature at the thermostat.
2 - it is a "heating element" made to heat the thermostat area so it opens faster.

I find both of these to be a little silly... I would assume it is:

3 - some sort of tension control on the thermostat so it opens some or all the way.

Any help on this one? Did i wire it wrong or do i need a new thermostat?

JH
The heater is there to force the thermostat open in anticipation of high heat demands, removing this will mean that the engine coolant will already be super heated. IE, when you floor it going up a hill whilst towing the heater will come on and force the 'stat fully open so you get maximum cooling effect. Rather than just waiting for 110C coolant to reach the 'stat.

OR it will mean that the heating element is running 100% of the time which will eventually cause it to burn out I would have thought?

Info from the WSM for clarification:

The die-cast coolant pump, driven by an ancillary drive belt, is fitted to the timing case cover. It contains the dual
coolant temperature sensor and the electrically heated 'map controlled' thermostat controlled by the engine
management system.

The map controlled thermostat incorporates a heating element inside a conventional expanding wax thermostat core which enables the engine management system to 'power' the thermostat open when the engine is under full load and/ or high output conditions. This provides sufficient cooling reserve through anticipation of the thermal load whilst allowing the engine to run at higher operating temperatures under part load conditions.

For further information refer to the Engine management system—V8 section of this workbook.
 

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Personally I really wouldnt risk messing with the cooling system, especially something as important as the thermostat considering it is linked with the ECM. If it was the Rover V8 already pushed to its limits then that's one thing, but the over engineered BMW V8 with no history of overheating?

Save yourself time and effort and do reglular coolant, oil and trans' oil changes if you want to save yourself big bucks.

My 2 pence of course :)

More Info:

Electrically Heated Thermostat

The electrically heated thermostat is used to regulate the engine coolant temperature. The thermostat regulates the coolant temperature depending upon engine load and vehicle speed. This allows the engine coolant temperature to be raised when the engine is operating at part load. Raising the coolant temperature while the engine is at part load has a beneficial effect on fuel consumption and emissions.
If a conventional thermostat with higher constant operating temperature is used, poor response when accelerating and in traffic could result.

The thermostat is controlled by the ECM is response to engine load against a 'map' stored within the ECM.

The map is based upon the following inputs:

  • Engine load
    Engine speed
    Vehicle speed
    Intake air temperature
    Coolant temperature.
The thermostat unit is a one piece construction comprising the thermostat, thermostat housing and heater element. The housing is of a die-cast aluminium. The electrical connection for the heater element is housed in the body. The heater element is an expanding (wax) element.

The thermostat is set to open when the coolant temperature reaches 10?C at the thermostat. Once the coolant has passed through the engine its temperature is approximately 11?C at the engine temperature sensor. If the ECM starts to regulate the system the ECM supplies an earth path for the heater element in the thermostat. This causes the element to expand and increase the opening dimension of the thermostat.

The warmer the element the sooner the thermostat opens and the lower the resulting coolant temperature is. The thermostat regulates the coolant temperature in the range 8?C to 10?C. The expanding element in the thermostat is heated to a higher temperature than the surrounding coolant to generate the correct opening aperture. Should the coolant temperature exceed 11?C the electrically heated thermostat is activated independently of the prevailing engine parameters.

Should the heated thermostat fail, (fault codes will be stored in the ECM) the EMS will ensure the safe operation of the engine and the thermostat will operate as a conventional unit.
 

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Discussion Starter #20
I actually did this mod, and returned it to stock... I was pulling some air/fuel via wideband and it runs incredibly rich like this, I guess the engine really is designed to be efficient at the higher temps. I suppose if you could get into the fuel tables/ecu you could retard timing or pull fuel back, but I'm not opening that can of worms.
 
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