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Thread: 540i running temp

  1. #1
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    540i running temp

    Hi,

    I recently finished my m60b40 swap in my e30 chassis. Everything is working fine and car as you can imagine is a permagrin to drive , especially with my current useless (for freeway speeds ) 3.46 rear end .

    Now, after doing some reading it seems newer engines are running hotter than the older engines , and if I understand it correctly it's for emissions .

    The stock instrument cluster temp gauge in the e30 is obvisouly designed with the m10/m20/m40 engines in mind, so I've used a brand new e30 temp sender that fit right into the rear water accumulator pipe.

    The issue I am having is the temp gauge after the car warms up sits a little higher than middle mark. I am thinking it's due to the running temp of the engine and the e30 sender and gauge not really meant or calibrated for the hotter running m60?

    So, what I would like to confirm is what is the nominal running coolant temperature for 540/m60 stock engine with new cooling system and working fan (clutch fan or electrical ) ?

    My plan is to do the following -
    - get another new sender and plot the temperature vs resistance by placing it in a pot of hot water and measuring the temp with a good calibrated tool
    - measuring the sender resistance on the car once the car is running and at idle , and then based on this data figure out if it's actually running within the optimal range or not ?

    Also, another option is to add a vdo temp gauge and sender and not rely on the cluster gauge to begin with.

    Thoughts ?

    Thanks and Merry Christmas !
    e30 84 340i m6x powered.
    e34 89 535i 5speed - current DD
    e24 89 635csi - maybe a DD?

    e34 93 525i (m50tu) - gone
    e39 540i 6spd m-sport - gone
    e53 x5 4.4l - gone
    e30 89 325i (m20) - gone

  2. #2
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    I have explained that before for E34 and E32: 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 indicatior at 12 o'clock can mean everything between roughly 75-110 degree Celsius depending on the setting of the coding plug in the cluster for a specific motor. Everything in between 75-110 is just 12 o'clock. Plus/ minus 1-2 mm to the right or left (deviation cased by the parts installed). I have tested this with 3 different cluster and installed them into the car within 5 minutes just to see the differences on the temp gauges with actually same temperature.
    The analog signal ist 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.
    That is written and shown here on page 4 of the instrument cluster check control training reference book for E32 and E34 http://www.e38.org/e32/BMW_pdfs/INST_info.pdf
    What is NOT shown in the English version I found in the German version, here a copy of that page showing the temperature diagram curve in picture 14, and there you see the socalled 'tableau' between 75-110 degree Celsius.
    http://photobucket.com/gallery/http:...ml?sort=4&o=18
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
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    Hi,

    I've seen your post , it doesn't really answer my simple question of what is the optimal running coolant temp for properly running m60b40, ignore the cluster / temp gauge as that isn't the single source of truth .

    75-110 is a huge range right ? I am not using an e32/34 cluster , what I am after is the actual coolant temp so i can compare it.

    Thanks
    Last edited by 84318i; 12-24-2017 at 04:23 AM.

  4. #4
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    It does, because what the BMW engineers are saying with this dummied up gauge is that temps up to 110 c are fine. I believe the M60s had 90 c stats so expect at least that.
    Given the hot rodded nature of the swap I'd be installing a mechanical gauge, at least temporarily, to correlate with the cluster's gauge. No need to change the E30 components they are measuring temp and don't care of what.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  5. #5
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    yes. The E32 740 even has a standard thermostat which opens at 95CEL , P/N is 11531702279
    Here for example is mentioned: M60B40:Normal engine operating temperature, °C (F) 95-100 (203-212) http://mywikimotors.com/m60b40/
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  6. #6
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    Thank you, stock m20 thermostat is 88c or 190f so the middle temp gauge mark right around there.

    So if 95-100c (203-212f) is the middle mark for m60 then it makes sense why e30 gauge isn't in the center .

    I'll measure the resistance of the e30 temp gauge sender at 190f to 212f and then post the values .

    I can then substitute that value with a resistor (or set a variable resistor to exactly that value ) and connect that to the pins going to the cluster and see what it shows .

    For fun I'll use that same resistance with my e34 m30 cluster and compare what the temp gauge shows.

    My guess is that the middle mark on the e30 temp gauge isn't where the middle mark of e34 temp gauge is for the same temp. Will be easy to confirm

    This will give me a piece of mind until I get a vdo gauge / sending unit installed (will need to tap the thermostat housing or get one of those radiator hose adapter sleeves to measure the temp of coolant)
    Last edited by 84318i; 12-24-2017 at 11:45 AM.

  7. #7
    moroza's Avatar
    moroza is offline MORΩN ΛABIA BMW CCA Member
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    Agree with Ross - use a good mechanical gauge at least initially.

    Stock US-spec M60 runs at a nominal 95C. Some other-market M60 cars run at 85C, and regardless of shogun's post I can confirm that my stock gauge showed a tick or two lower when I had that t-stat. Incidentally, I picked up about 1mpg switching from the 85C to the 95. For the 85C, I used a stock US-market M70 thermostat.

  8. #8
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    My 1995 540 runs about 1mm right of centre on the gauge and has done so for at least 250k kms.. Runs very well, no issues whatsoever.

  9. #9
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    Quote Originally Posted by moroza View Post
    Agree with Ross - use a good mechanical gauge at least initially.

    Stock US-spec M60 runs at a nominal 95C. Some other-market M60 cars run at 85C, and regardless of shogun's post I can confirm that my stock gauge showed a tick or two lower when I had that t-stat. Incidentally, I picked up about 1mpg switching from the 85C to the 95. For the 85C, I used a stock US-market M70 thermostat.
    Makes sense . Thank you!

  10. #10
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    Hi everyone Im completely new to this forum and not really sure what im doing.

    I have recently bought a offroad race car with the m60b40 engine and am struggling with overheating issues. I have had the engine rebuilt, heads skimmed, new gaskets, lifters, exhaust valves, shells etc.
    I have 16 litres of coolant running through a massive bespoke ali radiator with twin electric 16 inch fans. New water pump but it has no thermostat.

    So my question is about the 2 pipes that go through the valley, one small and larger, is the smaller one just to open the thermostat? As a sort of radiator bypass until the engine heats up?

    Also would there be any problem if i were to weld a plate in the pump between the cool water entering the pump, and the 2 valley pipes to force all hot water from the back of the engine through the radiator?

    thanks

  11. #11
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    Quote Originally Posted by Yellow Peril View Post
    Hi everyone Im completely new to this forum and not really sure what im doing.

    I have recently bought a offroad race car with the m60b40 engine and am struggling with overheating issues. I have had the engine rebuilt, heads skimmed, new gaskets, lifters, exhaust valves, shells etc.
    I have 16 litres of coolant running through a massive bespoke ali radiator with twin electric 16 inch fans. New water pump but it has no thermostat.

    So my question is about the 2 pipes that go through the valley, one small and larger, is the smaller one just to open the thermostat? As a sort of radiator bypass until the engine heats up?

    Also would there be any problem if i were to weld a plate in the pump between the cool water entering the pump, and the 2 valley pipes to force all hot water from the back of the engine through the radiator?

    thanks
    You just broke this forum, if not the car-related internet tonight with this post. I want to buy a ticket to your Island just to see this BMW powered car of yours. Pictures will have to do though - please post some.

    I have had several M6x BMW cars and still I have zero point zero idea about your cooling woes (and am sure the M6x smart guys here will weigh in eventually), but would love some details on how you are managing that motor from a DME/software perspective. Is it in a BMW car?
    Last edited by Henn28; 09-01-2022 at 07:54 PM.
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  12. #12
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    First off… what temp is the engine running at?

  13. #13
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    Hi buddy sorry for the late reply as have been working away.

    Its a 1974 rangerover chassis with a spaceframe cage setup.

    The link below shows the car on youtube

    Yellow Peril racing Hittersleigh 2 day Charity comp May 2022 - YouTube

    - - - Updated - - -

    Its getting up to 120 c and im having to back off mid stage.

    The engine has just been rebuilt by a race engine bloke.

  14. #14
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    That’s fantastic man. Looks like a blast, and what an awesome use for an an M62. I am trying to think of the water flow through the valley pipes on the M62 and keep coming back to the rear manifold. Since there are no other openings for water to/from the heads except on the back at the manifold, I think that manifold both provides cool water to the heads and takes the hot water coming out of the heads. In which case i have got to think that one pipe takes cool water from the pump to the manifold and into the heads, and the other takes hot water out of the heads to the pump so it can go into the radiator, via the thermostat? If so, clearly you can’t block either pipe off then.

    I ask about the DME and how the motor is controlled because BMW engineered a MAP cooling function into the DME where it could melt a wax plug in the thermostat and further increase cooling capacity when things got very hot, heavy loads, etc. I wonder if not having this on your motor, or it not working right is causing problems.
    Last edited by Henn28; 09-12-2022 at 05:53 PM.
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  15. #15
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    Wow that looks fun. Love how you’ve kept the OG shift knob.

    120, as you’ve noted is too hot. Have you validated your readings with a second independent measurement, like an IR thermometer?

    I wouldn’t mess with the crossover pipe between the heads on the back of the engine or the valley pan pipes. It would likely only exacerbate your issues or cause hot spots in one/both of the heads.


    Sent from my iPhone using Tapatalk

  16. #16
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    Silly question, but I assume the water pump is stock? Was it new with the motor rebuild? The impellers can fail in slow motion if not.

    when you get a chance I’d love to hear what power you are getting from the motor and what went into the rebuild to get more hp, if in fact it does make better than the stock 280 ish.
    Current BMW
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