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Thread: M60B40 740iL - what is considered normal running engine temperature?

  1. #1
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    M60B40 740iL - what is considered normal running engine temperature?

    My 740iL has recently had a bit of work done on its engine cooling system. Both the radiator and the auxiliary coolant pump in the heater circuit have been replaced. Both failed due to do brittle plastic fittings snapping off under the pressure of the system. Whilst all is good again now and the car is running fine, I have noticed the engine is now running cooler on the temperature gauge than it ever did before this work. Before the radiator + pump replacement, the temperature gauge in normal running conditions would sit at the midpoint exactly of the gauge at it's lowest point and rise to possibly 1mm higher than the midpoint at the highest.

    Now since the new parts have been fitted, the needle almost never reaches the midpoint of the gauge. It sits between 1mm below the midpoint at its highest and with a full needle width gap between the midpoint on the low side at its coolest on a long run with no traffic. Despite this seemingly cooler running, it does not seem to be affecting fuel consumption. Consumption on a recent long country trip averaged 11.7 l/100 and got down as low as 10.9 l/100 at one stage just before having to slow down for traffic coming into a township area. Around town in constant stop/start traffic, 13.5 l/100 is more normal. This equates to what the consumption was before the new parts were installed.

    My question is what's considered normal to see on the dashboard temperature gauge for these cars?

  2. #2
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    Original: 85C-90
    Nikasil Relief Package: 95-100

    Messes with guage a bit, not the most accurate. On our V12 with the 85C it's a needle width or two to the right, some have it dead center or a little left.
    Last edited by XAlt; 08-09-2017 at 04:57 PM.

  3. #3
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    There were in the past a lot of discussions what is right or wrong when the temperature gauge on the cluster temp indicator is right or left of the 12 o' clock mark.
    The fact is: Temperature indication on the BMW is not linear, they call it 'tableau', basically the indicator at 12 o'clock can mean everything between roughly 75-110 degree Celsius. Everything in between 75-110 is just 12 o'clock. Plus/ minus 1-2 mm to the right or left (deviation caused by the parts installed).
    The analog signal is processed in the instrument cluster and compared with data in the coding plug. A corresponding signal is sent to the instrument. Five temperature support values are stored in the coding plug. Exceeding the temperature limit stored in the coding plug will additionally send corresponding warning information to the check control and display it there.
    I once made a test with 3 different clusters within 5 minutes on my car, just to see the differences, it varied before/mid/after 12 ' clock

    That is written and shown here on page 4 of the instrument cluster check control training reference book http://www.e38.org/e32/BMW_pdfs/INST_info.pdf
    What is NOT shown in the English version I found in the German version.

    Temperatures in F and C http://www.nmia.com/~dgnrg/tempgage.htm
    Shogun tricks and tips for the E32 series are HERE!

  4. #4
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    Thanks for that. I'm not sure what the Nikasil Relief Package was, but my car still has its original Nikasil lined cylinder bore engine intact. It was never affected by the dissolving cylinder liners brought on by the Sulphur-rich Venezuelan oil imports down here in Australia, and now having done 230,000kms on the clock it's never likely to either. By 12 you mean you have the M70 engine?

    So it sounds as if 12 o'clock or a whisker above is normal to see on the gauge and mine now always comfortably below 12 o'clock by varying degrees, is too cold. I guess I'll get the thermostat changed out at the next oil service in that case.

  5. #5
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    Yes. 95C stats were added to run it hotter and decrease liner wear on Nikasil cars.

    It kept getting hotter and hotter, even on Alusil cars, the M62TU and M73N runs at 105-110C pretty consistently .
    Last edited by XAlt; 08-08-2017 at 11:28 PM.

  6. #6
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    Quote Originally Posted by shogun View Post
    The fact is: Temperature indication on the BMW is not linear, they call it 'tableau', basically the indicator at 12 o'clock can mean everything between roughly 75-110 degree Celsius.
    I read this diagram as meaning everything at 12 o'clock on the gauge can mean anything between 75°C and 95°C according to the tolerance given on page 8 of the instrument cluster training manual you linked to.

    Temp gauge.gif

    Using this pictogram, I would estimate my car is running nominally at 80°C at the low end, up to approximately 83°C at the high end. +/- the 10°C either side tolerance of course. I don't think this is anything dreadfully urgent that demands a thermostat replacement straight away, however I will probably add it to the works at the next oil change.

  7. #7
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    Quote Originally Posted by XAlt View Post
    Yes. 95C stats were added to run it hotter and decrease liner wear on Nikasil cars.
    Do you know what temp the OE thermostats were for the original Nikasil engines? That's what I need given that's still my engine and it's long past the point now of being vulnerable to the Nikasil liner wear issue. As I have been told, if the Nikasil engines made it to 100,000km milage without failing, then they never would thereafter. Something to do with the natural aging of the material inside the engine that occurs through repeated heat cycling making them immune from further chemical attack from the sulphur content in the fuel. Were the original thermostats 88°C or 91°C??

    Quote Originally Posted by XAlt View Post
    It kept getting hotter and hotter, even on Alusil cars, the M62TU and M73N runs at 105-110C pretty consistently .
    Yikes. Just one tiny little leak and instant vapourisation!

  8. #8
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    Your country version Australia aka hot climate version has t-stat 11 53 1 729 720 85CEL , see ETK, some 95CEL http://bmwfans.info/parts-catalog/E3...mp_thermostat/
    both o.k.

    By 12 you mean you have the M70 engine?>>>no, 12 o'clock shown on the gauge.
    No problem with your car.
    Shogun tricks and tips for the E32 series are HERE!

  9. #9
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    Quote Originally Posted by shogun View Post
    Your country version Australia aka hot climate version has t-stat 11 53 1 729 720 85CEL
    I would have said my car is more likely to need thermostat number 11 53 1 702 279 95CEL. It is Australian delivered and it has catalytic converters. In which case, with my needle indicating only 83°C at best and taking into account tolerances, only a possible 93°C at the hottest, then perhaps it is running running fractionally too cold. Something could easily have snapped off the broken shards of plastic fittings from either the auxiliary pump housing or the radiator nipple and become lodged in the thermostat stopping it from closing properly.

    For vehicles with
    National version Australia Yes L810A
    Or
    Gulf version Yes L822A
    And
    Catalytic converter
    Last edited by Legoman; 08-09-2017 at 12:33 AM.

  10. #10
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    85C stats were useful in the case of the M60 because.

    A. Faster heat into the cabin on a cold German winter.
    B. 2bar cap does its job and raises the boiling point, idiot proofing
    C. A compromise between power, wear and emissions

    75C stats exist for the M70 for super cold climates and drop into the V8.

    97314d1386886667-engine-temps-vs-wear-cylwallwearvstemp_640x480.jpg
    Last edited by XAlt; 08-09-2017 at 05:13 PM.

  11. #11
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    Quote Originally Posted by XAlt View Post
    85C stats were useful in the case of the M60 because.

    A. Faster heat into the cabin on a cold German winter.
    This is counter-intuitive logic is it not? I get that the lower the thermostat temperature, the quicker it opens and therefore the coolant circulating, but the M60 has the auxiliary coolant motor/pump mounted to the firewall near the front left suspension strut which is specifically tasked with pumping water around the heater circuit independently of the main water pump with the thermostat. Surely this would make any difference in the time taken to heat the cabin negligible at best? I'm afraid I can't test this theory for myself because I live where heating the cabin is never necessary at any time of the year, so the heater circuit for me is entirely redundant anyway.

  12. #12
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    Quote Originally Posted by Legoman View Post
    This is counter-intuitive logic is it not? I get that the lower the thermostat temperature, the quicker it opens and therefore the coolant circulating, but the M60 has the auxiliary coolant motor/pump mounted to the firewall near the front left suspension strut which is specifically tasked with pumping water around the heater circuit independently of the main water pump with the thermostat. Surely this would make any difference in the time taken to heat the cabin negligible at best? I'm afraid I can't test this theory for myself because I live where heating the cabin is never necessary at any time of the year, so the heater circuit for me is entirely redundant anyway.
    Aux water pump doesn't do all the work, you can bypass it and still get decent heat.

  13. #13
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    the aux water pump is just a comfort item to feed always a constant flow of hot coolant to the heater core, 950 l/h. And the aux pump does not always run, it only switches on when the heater is switched on and a certain temperature of the coolant is reached. (about 35 degree C).
    Without aux water pump it will heat less when engine runs in idle or low RPM, because now the main water pump supplies coolant (warm) to the heater core depending on the engine RPM, as the water pump is belt driven and the aux water pump is electric driven = idenpendant from the engine RPM.
    Aux water pump is also required when the car has a parked heating system, which was available as optional item.
    Shogun tricks and tips for the E32 series are HERE!

  14. #14
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    Just to quickly add... Shogun was right and I was wrong. My Australian-delivered 740iL with catalytic converters does indeed require the 85°C thermostat and not the 95°C I thought it did. I was reading the parts diagram wrong and am now convinced that yes, it should have the earlier opening temp one. This means my car must be running quite cold all the time now as my needle never makes it to mid-way anymore and quite often by more than 2 needle widths below the mid-line on the gauge. It must be running at no more than 80°C or perhaps even less.

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