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Discussion Starter #1
Is there a lower temperature thermostat available for the L322? I'm driving around in my 2004 with 80k on the clock just waiting for a hose or the expansion tank to blow. I cannot believe I need a 105C (221F) thermostat and a 1.5 Bar (22 PSI) pressure cap. Would really like to reduce the cooling system pressure to get some strain off the plastic and rubber, and reduce the temperature to get some load off the trans cooler.
 

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Hi billger & welcome to the forum.

The 'standard' thermostat opens at 85 deg. C. on the M62 engine (& the TD6, for that matter).

I just wondered where your 105 deg. C comes from?

Phil
 

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Ahhh, I'm with you now. 105 deg. C. is achieved using the electric heating element in the thermostat to raise the engine part-load efficiency.

Phil
 

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Discussion Starter #4
Thanks for the welcome.

"Part load efficiency" or temperature to achieve some imposed emission standard. In any case, I would like to get the normal operating temp down to the 190 deg F range. Does Land Rover use the same stats' in Europe?

Thanks,
Bill
 

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There's only one part number listed on Microcat so European/ROW models must have the same spec. as NAS, I guess.

The waxstat element is supposed to open at 85 deg. C if 'unassisted' by the heating element. I wonder what would happen if you just disconnected the wire to the heating element?

Phil
 

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Discussion Starter #6
I don't understand the workings of the heated element thermostat, but you may have my solution. I do know it provides over-temperature protection if you are under heavy load and would assume it opens fully to do it's thing. But does it energize or de-energize to open fully open?

Having my engine running at 85C all the time would make my day.

Bill
 

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If it is using a heating element to raise the temp to 105 C wouldn't the element be fooling the thermostat into thinking the coolant temp is higher than it actually is, then causing it to open sooner?
 

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Yep, you're right. I got that the wrong way around :oops: ...sorry. Heating the element above the water temperature will cause the thermostat to open more and reduce the water temperature. Don't pull the wire off !!!

I still don't understand what the 85 deg. C temperature specified in the manual is referring to?

Phil
 

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Discussion Starter #9
Great stuff - Thanks! Understand now. Solution is clip the line going to the ECU and ground it as the other wire must be ignition hot. Doesn't look like it will throw a check engine fault and the ECU can store all the codes it wants as far as I'm concerned. Will give it a try and let you know how I make out.

Really appreciate your help Folks,

Bill
 

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I see what you mean if the thermostat is 85 C then it shouldn't need a heater to make it open more to lower the temp further. Unless the cooling system isn't designed to handle Range Rover.

Its seems to me that the computer is using some complicated algorithms to determine when it needs to use the heated element to make the engine work at its optimum level based on that condition.

Probably something they have made a lot more complicated then really needs to be, but then again it might be an awesome feature. :think:

So your plans are to ground the heating element to make it heat all the time? It might burn out if it runs all the time or get the thermostat to hot causing it to always be open. Let us know how it goes.
 

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Discussion Starter #11
My guess is BMW did this to get that last tenth of a percent out of the emissions. Don’t think it will burn out as the water should dissipate the heat. If it does – oh well, have a spare thermostat assembly and it’s reasonable easy to change. The cooler motor will be easier on my tired cooling system and will certainly be less prone to detonation. I think it’s worth a try.
 

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Could I ask you to post an update in about three months. It would be interesting to know the effect. Also, if you could monitor your fuel consumption during this time for comparison that would be interesting too.

Good luck,
 

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Discussion Starter #13
Plan to do that exactly - stay tuned. Will monitor milage for both mid-range and premium fuel.

Bill
 

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Got into this post late, but I thought I would still add two cents.

During my mechanic days I was taught at a factory school that fooling a thermostat is always a bad idea. Beyond emissions, economy and efficiency, the thermostat is also attempting to manage thermal expansion and contraction of the block and all associated components (head, intake manifold if it contains coolant, etc.). Think of it like this, if the vehicle is level and under a constant load the cooling system finds an equilibrium with the heat generated by combustion and the thermostat selected level of cooling. Now introduce an increased load (going up-hill) and the engine temp will increase, the thermostat measures this and opens further to provide additional circulation and thereby cooling, in theory, the engine temperature should remain relatively constant. Now, remove the load, go downhill, the engine temperature will decrease and the thermostat will close or move toward closure to reduce circulation, to try to still keep the engine at a relatively constant temp. Without a thermostat, when all of this load/un-load was going on the engine block (and other components) would have been expanding and contracting a lot, to the point that eventually—and eventually is either sooner or later—the block will most likely crack, a head gasket will leak due to warpage, or, even, premature cylinder wall wear due to the cylinders changing shape, frequently. Lastly, the heater is expecting coolant to be within a relatively narrow temperature range, you would be surprised at how quickly cool or very cool air can be distributed on a cold day from a heater that is using coolant the has cooled significantly during a long downhill coast.

Fooling the thermostat to be open, or further open than it should be is the same as, or virtually the same as, removing it.
 

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Sroeb,

Whilst I agree with the general thought that thermally cycling an engine is more likely to induce thermal stresses on the engine, I dont think that what the original OP is aiming to achieve will have the effect of cycling the engine more as you outline in your post by the assumption that he's simply removing the stat. He's not looking to remove it, just push its opening value downwards from 105° to 85° . In fact, I reckon the electronically controlled stat which the M62 ( BMW model # ) engine has will cycle the engine more than it needs to.

The normal stat in the engine is an 105° stat and works in the same way an 85° stat will. Reach 105° and it'll open and maintain 105°. This was stuck in there to generally keep the engine at a high temp when under partial load conditions to improve emissions and consumption. BMW realise that under high load conditions, that this is too high a temp, and so added an additional booster to the stat to force it open more and make it behave like an 85° stat. When the engine thinks its under high load, it'll force open the stat and push the temperature down to a lower range. In some aspects, its good in theory, but practically, I think its pushing the boundaries a little - especially as time ticks on with engines. A quick scout around the web seems to indicate that temps around the 110° mark are considered overheat conditions.

I tow a reasonable amount, but i dont accelerate hard, or maintain high speed when towing. I've always thought when I finish the journey that the engine bay seems notably hotter than previous landrovers I've had. It really really feels like the engine has been cooking and running very hot. I never really thought I could do much of it until today when I've been replacing the alternator and removing the water pump.

If i'm towing for reasonable time frames, and at moderate loads ... is the engine thinking its in a high load range or does it think its in a partial load state ??

  • If its in high load, then it'll be trying to keep the engine down towards 85° ... a good thing
  • If its thinking its in the partial load range, then it'll be sitting up at 105° ... thats a high running temp for towing in my books. Especially when an overheat at 110° could be the case ... it wouldn't take much to push up into that.
  • If i'm in the balance between the two, then i'll i'll be changing between partial load / full load states. If so, then I'll be cycling between 85° and 105° back and forward throughout the trip ... thermal cycling springs to mind.
So i'm like the original poster ... how can I bring the temp downwards to the usual 85° ? and let the engine have some buffered temperature range which it can run in ... That way I wouldn't mind if I knew it was always running at 85° but had to put the foot down, and the temp's rose a little, I would still be in the original operating range of the engine.


*** sigh *** so much more complicated than it really needs to be. :think:
 

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Just thinking out loud here, but wondering if the T-Stat for a BMW 540i Sport is any different than the one we have in the MK3? A lower temp perhaps? I'll check with my sources.

Thanks!
 

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From what I've read:
Characteristic map thermostat
The thermostat is integrated in the housing of the water pump.
As on the M60, a conventional thermostat with integrated vent valve is installed on the E31 with M62 engine. This thermostat
opens at 85 o C.
A new characteristic map-controlled thermostat is used on the vehicle series E38 and E39 with M62 engine.
So which one is the E51 ... 5 series? ( edit ... apparently an 8 series ? )

Now ... just need to figure out if the ECU would throw a wobbler if the stat was a lower temp. I dont see why it should, the stat would be running the engine temp within the range it thinks is normal ( unless it expects to run up to 105° all the time )
 

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Hi Fisha,

This is a good spirited debate…

My comments about thermal damage to the engine are based upon the Wed Jul 22, 2009 11:00 am, post to ground the heater element wire and thereby energize the heater element permanently; from what I am reading the intent being to open the thermostat further or fully (most likely further) to achieve an 85 degree running temp. With all due respect, I stand by my original posting that this will allow some level of thermal shocking of, particularly, the engine block and is akin to a failed (open) thermostat that is not reacting and sensing the actual coolant temp.

Artificially creating the illusion of a hotter engine (ground the wire) is not shifting the effective range of the thermostats sensitivity but instead narrowing its sensitivity, if, it is sensing high coolant temperatures all the time… or sensing a higher temperature (margin) than that which actually exists. The thermal shocking will occur during periods of low-load when, for example, the vehicle is coasting down a grade when the thermostat would normally close or move toward closure. Instead, if I am understanding the operation of this thermostat correctly and applying this plan as described, the thermostat will remain open or more open than it should during this period of increased cooling which will result in a thermal change to the block… a shock. Steel, cast-iron, even aluminum does not like to willingly change shape and size without complaint, particularly when these castings have varying thicknesses and distances from the source of heating and cooling. One of the principal purposes of the thermostat is to try to keep the engine the same size during all loading situations.

High engine temps also contribute to high(er) combustion temps and the reduction of Oxides of Nitrogen and hydrocarbons. Lowering engine temp can lead to plug fouling, misfire, and all of the things that Rover owners, or any owners, dislike when dash lights turn on and ECU’s (or OBD) start to complain.

At the end of the day, I understand perfectly how the original poster feels about having an engine running that hot and under that much pressure… 22 PSI is a lot, and so is the temp. I suppose that the engineers who designed this heated thermostat were doing their best to have a hot engine run hot, and when it tried to get hotter, gave it an escape route by making the thermostat suddenly think it was getting even hotter and thereby provided (additional?) cooling.

For all of the technical reasons for high temp and high pressure, the danger is in a ruptured hose (as the original poster mentions) or blown-out “freeze-plug”. 105C = 221F, 10 degrees above boiling, so steam comes out. 22 PSI increases the boiling point by 66F, so we are now potentially talking 287F for a fully stuck closed thermostat, and hose that ruptures as a result of max pressure and temp, that is high-pressure, deadly temp steam. Drive it up a mountain to a lower atmospheric pressure and things get even hotter (lower boiling point) and higher pressure in the event of a rupture (extraordinarily vigorous discharge)… Maybe this engine is really a steam engine in disguise?

… And then of course there is the whole discussion about heating element longevity when the heating element is permanently heating, when it may have been designed to be intermittently activated…

All the best.
 

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I agree with the idea of fooling the existing system to force open the thermostat is not a good idea, as you are relying on the principle cooling to be done by the section of the stat which is only meant for the additional cooling facility.

I just think that there are times / situations / uses where if you could replace the stat with a lower temperature one, then it may suit the user of the vehicle better. A complete replacement of the existing stat to a lower temp one would mean that the new stat would keep the engine running at a constant, lower temp. It wouldn't necessarily be shocking the system, it would be working just like any other generic stat, opening an closing in line with maintaining its lower temp and keeping the block at a constant lower temp.

Nowadays, the engine management and fuel delivery is way better than years gone by and running at a slightly lower temp I dont think is really going to lead to that much fouling or mis-firing compared to the old style lucas " dump the fuel in, hope it burns" affair.



I went into the BMW garage yesterday, and after buying some coolant for the RR ( cause its waaay cheaper there than the LR dealer ) , I pestered the poor lad to go through the parts system looking at the e31 ( 8-series ) 4.4 V8 thermostat.

Basically, according to the pictures ... it looks like the 8-series has a normal generic stat ( which I assume opens at 85 degC as per the documentation ) without the over-boosting open feature of the 105degC stat. It also has a slightly different housing cover which doesn't have the plug for the heating element moulded into it - but it looked like it would have just bolted on as normal. Lastly, according to the system, the stat is compatable with the 8-series, the 5-series and 7 series models.

However, ( aint that always the case ), I then asked the prices.

The housing cover was about £21 ... which seemed ok. The stat was about £70 .... :shock: ouch. If it had been about 10 quid ( loike any other generic stat (, then I would have ordered them then and there to try out. But at those prices I held off.

I do still think this is an achievable feat .... and one which if you can find the correct parts, should just be a case of unplugging the hose to the stat housing, unbolting the housing and stat and replacing if with a lower temp stat and housing, plugging the hose back on, job done.
 

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Wait ... theres more .... Dont ya just love a good debate !!!

I went looking around for the 8-series bits and came across a good site with all the pictures and part numbers, here is what I am talking about from the 8-series .... see how the stat and its housing ( parts 6 and 7 ) dont seem to have the bit for the electronic heater doodah.



and compare it with a later model picture from a 7-series which DOES have the characteristic control on the stat ....




if you look at this page .... 8-Series Parts - Water Pump

and scroll down the page,it would appear that for the thermostat itself ( part number 7 ), there are a variety of different ones .... and going by the part numbers of 85C... and 95C... that there are different temp ones.


Now the question is ... are they cross compatable .... well I think they are.

The 8 series page: 8-Series Parts - Water Pump

The 7 series page: 7-Series Parts - Water Pump

shows that the sealing o-ring on both versions is:

Gasket ring
Part Number: 11 51 1 705 408
Detail: 4,0X76,5MM

Which to me implies that if the seal is the same diameter, then the thermostat will be the same diameter too ... and so should fit.

I imagine that the hose connection on each of the housings are going to be the same ... so I imagine it'll just clip on. ;)


Last minute edit:

Found a stat for £20 .... here
 
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