M60 running temperature

[Jean]

Hi,

I am going to say right off the bat that I may be overthinking this, but figured this would be helpful to know for others doing this swap as well.

I've recently measured my e30 cluster temperature gauge and plotted 1/4, 1/2, and 3/4 temp gauge needle location based on the ohm reading from the single pole sending unit 12 62 1 710 512.

Ive confirmed these numbers using two clusters and used two ohm meters ,
Variable resistor and also fixed 5% resistors so I am pretty confident in these numbers .

E30 temp gauge at end of the blue mark needs about 115 ohms, 1/4 mark needs 70 ohms, 1/2 mark is 46 ohms, 3/4 mark is around 32 ohms red starts at 24 ohms and maxed out at 14 ohms .

Next, what I did was used a new 12 62 1 710 512 sending unit and measured its resistance based on the hot water temperature using a cooking digital thermometer.

Here is what I've ended with

68f is 774 ohms
83f is 376 ohms
130f is 197
140f is 161
150f is 135
160f is 112
170f is 95
175f is 81
180f is 74.5
185f is 68
190f is 64.5
195f is 61 ohms

So, having this data you can see that middle mark of the e30 temp gauge using 512 sender would mean it's over 195f.

Tomorrow I'll measure again using digital infrared thermometer to what numbers I get from the 512 sender.

And, also I'll measure my 512 sender on the running m60 at the 1/4 and 1/2 mark on the gauge in the car and report back .

The point of all of this is to validate how accurate our temp gauge readings are when using 512 sender on m60 engines .

Now, it's a known fact m6x engines run hot, but I figured it would be good to have some good data to understand the delta etc.

Any thoughts or other data points ?

Thanks

[Jean]

What I would love to have as data point is someone with a stock e32/34 540/740 car who can measure their running temp using infrared thermometer at the thermostat location and rear water accumulator pipe .

Or, if you have ads cable and software and can report the running temperature that the DME is reporting using the dme engine coolant temp sensor , at 1/4 and 1/2 marks.

Anyone ?

[flyboyx]

its really good of you to think of this.

i think 195 degrees in the middle of the gage is about perfect. that is the typical factory designed operational temp of the engine or close to it.

[The Dark Side of Will]

The '02 A6 I used to work on liked to run at 210.
"Modern" aluminum engines with recirculating cooling systems can run fairly hot and be just fine because the recirculating system keeps the temperature even throughout the engine and there aren't the same kind of differential expansion problems like there are with an aluminum head on an iron block.

All that being said, BMW finds ways to make anything problematic... <cough> M54 <cough>

[dasmanschaft012]

M60s are fine to run up to at least 230F.
Its not a great comparison, but the aluminum LS3 in my vette runs at 220 pretty consistently. I wouldnt be worried unless you get over that point.

[BUDNUNTA]

Been going through this on my car over the past week
It been over 38'c outside and my car has been running between half and 3/4, fan comes on at 99 and turns off at 95 which is standard for a LS1 commodore

The newer all alloy engines just run hotter. I'll just be adjusting the e30 gauge so normal operating temp is in the middle

[JGood]

My m60b40 and m60b44 hang between 3/8 and 1/2, for the entire 6 years/40k miles I've had it it my e30. I'm running a Mishimoto Z3M radiator, with a shitty Pep Boys 16" fan running off a BMW temp switch in the radiator. I've never gone above half, even sitting idle in 100+ degree humid weather for hours. The fan has to run nearly full time in those conditions, but that's worst case scenario. However, while driving back roads or highways where I stay moving, it'll be down at 3/8, so regardless of what fan or temp switch you have, your normal operating temp while driving should be below half, unless you stop.

That said, I had the fan wired backwards at one point, and it shot up the red zone in about 5 minutes flat while idling in hot weather.

[Jean]

JGood - that's good! Have you measured your temp using an accurate gauge, at the thermostat or rear water accumulator pipe? Also, what Thermostat are you using?

The reason why I am doing all this testing is because the temp gauge sender (we are not talking about the fan switch here just to be sure), is calibrated for specific temperature range. It doesn't care obviously what engine it's measuring, but what matters here is that the M60 runs hotter, so the stock e30 temp gauge will not be accurate.

[Mykk540i/6]

Will the E30 gauge temp sensor not thread into the M60 coolant crossover?

[Jean]

It does, that's what I am using as it works with e30 gauge . But it's off as the engine temp on m60 is higher than m10/m20/m40 that this sensor is meant for . The m60 sensor ohm reading is so off that the e30 gauge won't even read it at all.

Today I let the car warm up and took her for a spin until the gauge was showing 1:00 temp reading . I then used an infrared thermometer and the highest temp I was able to read off the thermostat housing was 189f(87c) rear pipe showed 160f (71c) and the lower oil pan showed 180f, heads showed 165f.

So, reading on the gauge cluster is way off . 1:00 on cluster , yet engine temp is 160-189f depending on where you read it from .

I didn't have time today to measure the ohm reading off the e30 sender while measuring the temperature at the same time. Will do it in the next couple of days , also waiting for my ADS cable to arrive and that will let me read the temp. that the dme is reading off the engine coolant temperature sensor it's using (not the gauge sender). That will be a good data point.

[Mykk540i/6]

As hacked as it may sound, you could install a small potentiometer between sensor and cluster. Maybe 20 ohm? only use two of the three legs of the pot. While M60 is at operating temp you could adjust potentiometer to bring needle back to middle of gauge by increasing resistance.

Once that resistance value is known you could install a resistor if you don't want a clunky potentiometer inline.

[Jean]

Yep, can easily do that . I hooked up a 300 ohm potentiometer to my spare cluster and mapped the readings (e30 temp gauge needle location. Vs sender ohm readings ) that way :)

The main concern is to verify all this by testing and measuring first.

[JGood]

With an infrared thermometer, I see about 190f at the thermostat housing. My gauge is about 1/2 at that point.

e30 gauge clusters are 30 years old at this point, and are known to be failure prone with the SI boards (which impacts gauge operation) and even the main board itself. As a matter of fact, I just had an SI board transistor failure impact tach operation 2 weeks ago.

[Jean]

Thanks for confirming your temp with infrared thermometer :)

Yep, well aware of the cluster / si boards issues. All those issues have already been handled and my results are consistent with now 3 clusters with good boards.

I'll post an update once I am able to read the temp off the dme using ADS cable and DIS software and correlate the various data points.

Have a good weekend all!