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M6x e30 - More cooling power?

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    Originally posted by DIIRTY-30 View Post
    I have similar issues, I watch the temp bounce between 220-235 on the obd1 m62, running m60 wp & thermo/z3m rad and a spal 16" pusher w/gasket against rad. No ac/heater though, but i've run a block test and compression a few times to make sure it isn't a HG issue since my donor was 150k.

    I still haven't determined if the temp gauge is faulty or what but my readings on my vent says its 223-225 but cluster will show 3/4 at operating. Oil temp will sit about 205-220 roughly around 40psi if memory serves correct. Haven't had the chance to auto-x it yet but i've had some fun and beat it around. I've been on the fence about chopping some holes in the hood and ducting the radiator since I've noticed pulling the hood gasket made about a 5-10 degree difference when I was looking at 235.

    My neighbor who just sold his miata for an e36 m3 had a few vents on his hood cut out so I stopped him one day to gab. Told me he's looking at around 15-20 degree difference with the vents since he installed them. Granted we're talking a NA stock 4 cyl but thats a pretty noticeable difference. I believe he was running a dual 8" puller set up wired to in cab switch.

    On the other hand, my e38 m62 runs around 225-235 in traffic/under load and have read that the m62s run higher temp for emissions. I've yet to meet someone local with an m60 swap to hash out the details between our two cars but would like to figure out the variables between them.
    It's most likely not the gauge or the cluster, the e30 cluster temp reads the 1/2 mark when it sees about 46 ohms and get's to 3/4 mark when it sees around 33 ohms from the sender. I read this by connecting a variable potentiometer in place of the sender and basically ran the pot from cold to green and recorded ohm readings vs gauge needle position.

    What I then did was placed another brand new brown e30 sender in a pot of hot water an measured it's temperature using an infrared thermometer and recorded the ohms vs. temperatures .

    What I found that the stock e30 temp gauge when using e30 sender will read past 1/2 mark for the operating temperature of the m6x as these engines run hotter than e30 engines.... obd2 engines run hotter stock for emissions.

    When my e30 cluster gauge was showing at or almost 3/4 mark I used my infrared thermometer to check the temperatures at the water pump, the coolant pipes, top of the radiator and rear coolant pipes and have not seen temperatures higher than 210f.

    e30 cluster will read on the high side for 210f, but the stock e32/e34 clusters with their matching temp senders for these engines will not read as high.

    Just sharing what I've learned by doing some measurements and readings. I've since purchased a stand alone vdo vision temp gauge and sender that I've yet to install for peace of mind (and same for engine oil temp).
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      Excellent work Jean! Very thorough


        The temp reading high is a mixture of a couple things.

        1. The E30 has an unbuffered temp gauge, meaning it will go up and down relative to the specific ohms it sees.

        Most M62 equipped cars had buffered temp gauges which showed the needle at dead middle between a range of temperatures:

        This range of temperatures could go up to 95c and still be considered normal operating temp. On an E30 cluster this would show as a few ticks past middle.

        2. The E30 gauge is calibrated to show 80c as middle, the M60/M62 ran a few different thermostats, a 95c thermostat (e34) and 85c thermostat (E39/E38).

        As Jean pointed out, these engines are meant to run hotter. Using a gauge calibrated for a cooler engine will always show the engine as running hot.

        BMW started using 95c thermostats on the Nikasil blocks as it seemed to slow some of the damage that was being caused by sulphur in fuels.
        Your resource to do-it-yourself and interesting bmw and e30 stuff:

        Your resource to tools and tips:


          Hmm. Based on my temp readout in tunerstudio, 180f (82c) is the second mark on my E30's temp gauge.
          '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
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            M6x e30 - More cooling power?

            Iím sure it will take some time figuring out, thereís a guy on Bimmerforums who had clutch fan and bigger electric fans or 2 of them? I gotta look in his e38 that he tracks, anyways,
            After a straightaway during braking his car has a heat spike but after he accelerate it goes down. Anyways, time to make a fan shroud?

            You should add a temp gauge so you have an accurate reading and double check your temperatures with a infrared from harbor freight and make sure nothing is clogged, fully opening thermostat, etc., just as a double check if you havenít done that.

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