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Thread: M52 is starting to get hot after about 25 minutes (230°)

  1. #1
    Join Date
    Mar 2020
    Location
    Fort Mill SC
    Posts
    5
    My Cars
    3x E36, Turbo Miat

    M52 is starting to get hot after about 25 minutes (230°)

    I have a M52 engine with heater hoses deleted/rerouted, clutch fan deleted and replaced with a Mishimoto electric fan pulling air, and near brand new coolant. Car has run steady between 160-190° and now will creep up especially in traffic to the boiling point of the coolant, about 230°. I am fairly certain there is no thermostat too, I actually acquired the car through a trade two months ago. Car always ran pretty cool if i wanted it too until now. Any suggestions for diagnosis or troubleshooting/where to start would be great!

  2. #2
    Join Date
    Aug 2014
    Location
    Los Angeles, Ca
    Posts
    156
    My Cars
    89 E30 S52 94 E34 S52
    Make sure electric fan is installed correctly, I’ve received cars where it’s not in the correct position. Thermostat is def required


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  3. #3
    Join Date
    Mar 2020
    Location
    Fort Mill SC
    Posts
    5
    My Cars
    3x E36, Turbo Miat
    I checked the fan when i first got it and it’s installed behind the rad pulling air. And i can run no thermo fine it just takes a long time to warm up. But the issue is that it’s getting hot lol. Just weird that it’s been great until now.

  4. #4
    Join Date
    Oct 2003
    Location
    Seattle
    Posts
    5,776
    My Cars
    99 M3
    Put the thermostat back in, as the ECU/DME is adding more fuel for far to long a period of time.
    What temp does the puller fan start? Is it a single speed or multi speed?


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  5. #5
    Join Date
    Jul 2010
    Location
    Murrieta, CA
    Posts
    9,530
    My Cars
    '94 325iC, '08 328i, E93
    I bought Frankenstein, now he won't waltz, what's wrong?

    It kills me that you have custom everything and want people on the 'net to help. This is one of those times when you figure out why you don't buy this kind of stuff. Sorry man, but everything you hear here is a guess.

    My guess is that your water pump is not pumping. But the reality is, any of the stuff you describe as having been changes could easily be the problem. You're describing the electric fan not coming on. Fan thermostat, that sort of thing. But, if the fan was not working, then driving at speeds above about 30 should bring the temp down again if the problem is from airflow across the radiator. A failed fan clutch (viscous couple) symptom is that the car heats in stop-n-go traffic, but cools when traffic is in a go cycle. The thing is, airflow across the radiator in standing traffic does not exist, the fan clutch heats up, locks the clutch, the fan then draws air through the radiator. When the car is moving again, the clutch cools, releases and goes to a free-spin mode to reduce fuel consumption. The air forced through the radiator because the car is moving is enough air to cool the radiator. Even if the electric fan was not working, the airflow through the radiator at speeds above about 30 should cool the engine. Radiator blockage is also an issue that can lead to your symptoms. So, you see, you can have any of a number if problems that demand a better description of the symptom set.

  6. #6
    Join Date
    May 2017
    Location
    Owings, Md
    Posts
    1,105
    My Cars
    1998 328i
    Is your electric fan ever coming on? I understand the mechanical fan was removed, am I correct in assuming that the auxiliary pusher fan was removed as well (which would make sense). Your problem probably lies in the controls for this aftermarket fan, if it is all configured correctly there is no reason it shouldn't work as this is how virtually every modern car is set up, but seeing as how it is an aftermarket mod, it may not have been powered or controlled correctly. In the stock configuration, the auxiliary fan should come on any time the AC compressor kicks on (AC or defrost) or when either of two temp thresholds are reached at the radiator, the sensor for this is on the radiator, on the passenger side of the car (assuming LHD). Most aftermarket fan mods tap into the auxiliary fan controls but run them to a relay (or pair of relays) because the stock auxiliary fan circuit does not have adequate amperage to power a fan to fully replace both the aux fan and the mechanical fan. Figure out how yours is wired and you will probably find you problem.

    I would also be curious about how the heater is bypassed. There are aftermarket block off plates that install on the back of the head but it doesn't sound like a smart idea to me at all, the stock setup always allows coolant flow out from the back of the head whether it passes through the heater core or bypasses the heater core, blocking this off seems unwise to me but I know some track cars are setup this way so maybe it's no problem. In either case, I would suggest figuring out how yours is set up.
    Last edited by gdavid; 03-24-2020 at 09:02 AM.

  7. #7
    Join Date
    Sep 2006
    Location
    NW suburban Chicago
    Posts
    16,302
    My Cars
    hiss by my window
    Quote Originally Posted by JDStrickland View Post
    I bought Frankenstein, now he won't waltz, what's wrong?

    It kills me that you have custom everything and want people on the 'net to help. This is one of those times when you figure out why you don't buy this kind of stuff. Sorry man, but everything you hear here is a guess.

    My guess is that your water pump is not pumping. But the reality is, any of the stuff you describe as having been changes could easily be the problem. You're describing the electric fan not coming on. Fan thermostat, that sort of thing. But, if the fan was not working, then driving at speeds above about 30 should bring the temp down again if the problem is from airflow across the radiator. A failed fan clutch (viscous couple) symptom is that the car heats in stop-n-go traffic, but cools when traffic is in a go cycle. The thing is, airflow across the radiator in standing traffic does not exist, the fan clutch heats up, locks the clutch, the fan then draws air through the radiator. When the car is moving again, the clutch cools, releases and goes to a free-spin mode to reduce fuel consumption. The air forced through the radiator because the car is moving is enough air to cool the radiator. Even if the electric fan was not working, the airflow through the radiator at speeds above about 30 should cool the engine. Radiator blockage is also an issue that can lead to your symptoms. So, you see, you can have any of a number if problems that demand a better description of the symptom set.
    Love it! May I use that?
    OP, Sorry, no clues from here. Someone has managed to defeat a good portion of your car's cooling system, successfully.

    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

  8. #8
    Join Date
    Aug 2014
    Location
    Los Angeles, Ca
    Posts
    156
    My Cars
    89 E30 S52 94 E34 S52
    To add on what the gdavid, if you verify the sensor is bad; get the 318ti sensor, low speed comes on quarter and high speed come on at half.


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