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Thread: 1999 M3 starts running hot at odd intervals with and without A/C.

  1. #1
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    1999 M3 starts running hot at odd intervals with and without A/C.

    Hey guys, I've been searching the forums about my issue and I'd like to share my experience to see if anyone can link a direct thread has had an issue similar to mine.

    Car background: 1999 BMW M3 Coupe with a Eurosport Supercharger, a Zionsville Fan Shroud w/ metal expansion tank (important later), and Mishimoto Radiator. PPI showed no signs of major wear and the compression test revealed all cylinders were well within good boundaries (all cylinders between 190-200 psi). Bought in Washington (car @114k miles) and drove it 1500 miles back home to Phoenix, AZ (car @116k miles).

    Issue: During the drive through Washington, Oregon, and Northern Cali where the temperatures are relatively cool (70-90F), the car was running fine at highway speeds with the A/C on for the first few hundred miles. Then I noticed when I started going uphill with the A/C on, the car's temps started going up. I never let it hit the 3/4 mark but as soon as I saw this temp increase, I turned the A/C off and the heater on full blast along with the little dial under the vent to red. This immediately dropped the temps back down to normal and I didn't even have to pull over. Once the uphill was over and the downhill began I turned the A/C back on and the temps remained constant even when it was flat. Anytime I turned the A/C on, I'd notice a slight, ever so slight, effect on the car while driving. It was like it was slowed down ever so slightly. Like you could FEEL when the A/C compressor came on. But as soon as it hit any little uphill the temps would rise with the A/C on. So during the trip, I always turned the A/C off when going uphill and that usually worked.

    That is until I got to Southern Cali on the I10 headed towards AZ where the temps were high (100-110F). At this point, I couldn't drive the car with the A/C on no matter what. As soon as I would turn it on, the car's temp would eventually start to increase. Then once I got to really high temps (105F+), it was starting to run hot going 70-80 mph with cruise control on the whole time. So I had to keep the heater on full blast every now and then until I got home (worst experience and 300 miles of my life). Even when running at a lower speed (60-70 mph) the car's temp would eventually start to increase (hopefully this continuous heat cycling didn't screw anything up too bad). For now, I just chalked it up to the fact that I had driven it for 22 hours straight.

    Attempts to diagnose: Once the car cooled down after a few hours, I checked the coolant level and it looked fine. Nothing out of the ordinary. The next day after I let the car rest for a bit, I tried to bleed the coolant but I could not find the bleeder screw that's usually on the expansion tank. I tried disconnecting the hose on top of the radiator that connects to the expansion tank on Zionsville radiators, and bleeding it that way per instructions I found in other posts, but nothing was coming out of the hose (the hose in question here). Now I know the pic shows the coolant splatter, I noticed I did not put the cap on right and it was loose while I was driving it later (the pic was taken after the bleeding and driving). The car ran for up to a minute with heater on full blast along with front window defroster on and still nothing was coming through the hose. So now I'm at a loss. Am I not bleeding this correctly? Is there a specific way you're supposed to bleed a Zionsville radiator and metal expansion tank since it does not have a bleeder screw?

    After the failed bleeding attempt, I hopped in it again and started to drive it again to see if it would heat up again. The A/C started acting weird. I drove it for about 5 mins with the A/C at 60 degrees on full blast and it was working fine until the cool air just stopped coming through. It gradually got warmer and warmer until only "room temperature" air was coming out. So then I parked the car in the garage and let it rest for a bit.

    Once I turned it on again and let it idle to check if the aux fan was running with the A/C on and it was not running while idling with A/C on. My brother recommended that I drive it again for a bit and see if the cool air returns eventually. I did, and the cool air did return so I'm assuming the aux fan did turn back on. So, I decided to drive it around for a bit going 45-55 mph. After about 10-15 mins of driving, the car started to heat up again! The cool air did not stop coming through when it started heating up.

    Where I'm at now: After reading about a similar issue a guy here had back 2009 here, with a nearly identical story to mine, I began to think it was the thermostat. But, if it was the thermostat, wouldn't it run hot even when the A/C is off and when the heater is off? Other people have mentioned the aux fan which is what I'm suspecting might be the issue. If it's turning off at random intervals, the radiator might not be dissipating enough heat. But going 45-55 mph, is the fan even a factor to the cooling at that point?

    Thanks for taking the time to read my essay of an issue. I'm stuck on what to do next. I'd like to actually bleed the coolant the right way so I'd appreciate it if anyone could give me some advice on that as well.
    Last edited by pasllani; 07-19-2020 at 07:03 PM.

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    OK - this is a fan problem.

    You'll get a lot of advice from guys with track cars, but you need a new aux fan and a new main fan. There are pros and cons of going electric, but right now neither fan is doing its job.

    [Edit]

    Did I mention this is a fan problem?

    I've had this exact same thing happen to me. I live in Austin, and had this happen on the way to Dallas one time (between 105 and 110 degrees).

    It's a bad aux fan AND a bad main fan.

    The AC needs to be able to cool the condenser or it won't... condense. If your aux fan and your main fans are dead and you aren't moving, it won't cool the condenser. If you get moving, it will cool it, but the extra heat will heat up the air cooling the radiator and now THAT won't get cool enough to keep the car cool under load.

    There are guys with track cars who will claim that the fans do nothing at speed. This is completely false for a road car with a fan shroud, AC, etc. I've experienced this too on multiple occasions. Triple especially true for places that see triple digits for most of the summer.

    Pressure builds up, funneled through both the aux fan / shroud in front and the main fan / shroud in back. If you get electric fans that you can turn on and off you'll see that flipping the fan switch (at speed) will keep the car running much cooler than when they're off, no matter how fast you're going (35, 55, 85 - it doesn't matter).

    If the aux fan doesn't turn on when you turn on the AC, it's dead. It's as simple as that. It can cycle a lot when the AC is running, but it will be on far more than it's off, and it will start immediately even if the car is cold.

    If it just blew the fuse - guess why it blew the fuse? It's dying. You need a new one. A fuse could limp you around for a day or two, but it'll blow again and you'll be in trouble again.

    On the new fan - make sure the female pins inside the plug on the fan are the right size to make contact with the male pins on the car's plug / wiring harness. This is why I had that issue on the trip from Austin to Dallas. You can crimp them down to make contact, but be aware this mismatch can happen sometimes and leave you scratching your head, wondering why the new fan isn't working.

    You need to check the main fan, too - roll up a newspaper and brush it across the top of the fan blades. If you can stop the fan when the car is hot, the clutch on that fan is toast.

    I'll let you do your homework on whether you want to convert the car to an electric main fan or keep the factory clutch / belt driven fan.

    I've been in Dallas and Austin for ten years. I've been to this rodeo more times than I can count.

    This is very simply a problem of dead fans.
    Last edited by blckstrm; 07-06-2020 at 10:49 PM. Reason: Added info

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    Quote Originally Posted by blckstrm View Post
    OK - this is a fan problem.

    You'll get a lot of advice from guys with track cars, but you need a new aux fan and a new main fan. There are pros and cons of going electric, but right now neither fan is doing its job.
    +1

    People will insist that the front fan does nothing at above 30mph or some made up number, but that's simply not the case. Air is going to flow through the path of least resistance, and through the radiator is not that. A fan will force slower moving air in the front of the car through the radiator well past 30mph. Now triple digits are a different story, but normal cruise speed fans do still do some work.


    Also, you mentioned a Zionsville radiator, does it have a front shroud?
    Last edited by Hova; 07-06-2020 at 10:49 PM.
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    Haha - sorry Hova, I pulled out my laptop to edit my post and added a bunch of explanation I didn't want to type on my phone.

    ---

    We can point you to places to learn about the benefits and drawbacks of going to an electric fan, and we're happy to answer questions you may still have.

    For reference, this remains my DD with full AC (I mentioned I'm in Texas, right?), no hood vents, but I do have an aluminum undertray to close off the underside and all other ducting in place, etc. I'm running both a normal, stock, shrouded aux fan, and running a Derale 17" 18217 pusher/puller fan integrated with my factory main radiator shroud. I wrote that up here: https://www.bimmerforums.com/forum/s...perience/page2

    I've had to tinker with the wiring to get it right, but the correct solution (which I'm finally running) is a fuse / relay each for both high and low speed (I'm told BMW uses two relays for the aux fan, so it makes sense I was blowing fuses and melting relays with both high and low wired together and running through the same relay). I am triggering the new electric main fan off the aux fan switch, and just this last year went to a lower temp switch to help stave off heat soak. It was 95 today and the hottest the car got was 204 going up a long uphill.

    If all of that sounds confusing or downright scary, the factory belt driven fan is a great solution and will keep the car cooler than almost anything else you can do. It moves more air than anything else and has no downside if it's new.

    ---

    A couple other points of reference since you're new and dealing with a cooling issue. The needle hits 12 o'clock about 175, and starts moving again at 225.

    This is significant because 225 is the boiling point of 50/50 water / coolant mix. So if your system ISN'T holding pressure, that's where you start getting in trouble. Also where you should be realizing there's a problem. You did a great job managing this, by the way. It's exactly what any of the rest of us would have done, too. I don't remember the temps for the upper line and the start of the red zone, but my recollection is that the red zone starts where 50/50 mix boils EVEN UNDER standard system pressure. Thus it's BAD.

    ---

    One last note - I'd stop chasing the cooling system itself. Maybe you'll want to replace the expansion tank if it's original. Maybe your hoses are old and need to be replaced. But if the abuse you just put it through didn't cause any leaks or blow up the expansion tank, you're probably fine to wait on that stuff.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  6. #6
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    Quote Originally Posted by blckstrm View Post
    OK - this is a fan problem.

    You'll get a lot of advice from guys with track cars, but you need a new aux fan and a new main fan. There are pros and cons of going electric, but right now neither fan is doing its job.

    [Edit]

    Did I mention this is a fan problem?

    I've had this exact same thing happen to me. I live in Austin, and had this happen on the way to Dallas one time (between 105 and 110 degrees).

    It's a bad aux fan AND a bad main fan.

    The AC needs to be able to cool the condenser or it won't... condense. If your aux fan and your main fans are dead and you aren't moving, it won't cool the condenser. If you get moving, it will cool it, but the extra heat will heat up the air cooling the radiator and now THAT won't get cool enough to keep the car cool under load.

    There are guys with track cars who will claim that the fans do nothing at speed. This is completely false for a road car with a fan shroud, AC, etc. I've experienced this too on multiple occasions. Triple especially true for places that see triple digits for most of the summer.

    Pressure builds up, funneled through both the aux fan / shroud in front and the main fan / shroud in back. If you get electric fans that you can turn on and off you'll see that flipping the fan switch (at speed) will keep the car running much cooler than when they're off, no matter how fast you're going (35, 55, 85 - it doesn't matter).

    If the aux fan doesn't turn on when you turn on the AC, it's dead. It's as simple as that. It can cycle a lot when the AC is running, but it will be on far more than it's off, and it will start immediately even if the car is cold.

    If it just blew the fuse - guess why it blew the fuse? It's dying. You need a new one. A fuse could limp you around for a day or two, but it'll blow again and you'll be in trouble again.

    On the new fan - make sure the female pins inside the plug on the fan are the right size to make contact with the male pins on the car's plug / wiring harness. This is why I had that issue on the trip from Austin to Dallas. You can crimp them down to make contact, but be aware this mismatch can happen sometimes and leave you scratching your head, wondering why the new fan isn't working.

    You need to check the main fan, too - roll up a newspaper and brush it across the top of the fan blades. If you can stop the fan when the car is hot, the clutch on that fan is toast.

    I'll let you do your homework on whether you want to convert the car to an electric main fan or keep the factory clutch / belt driven fan.

    I've been in Dallas and Austin for ten years. I've been to this rodeo more times than I can count.

    This is very simply a problem of dead fans.
    Ahh okay thanks for the info! We checked the aux fan relays and replaced them with the fog and horn relays just to test them out and there was no difference between the swaps. I also already have an electric fan and it seems to work fine since the car does not heat up while it’s idling. Or at least throughout my testing of it. I believe it’s the zionsville shroud with fan. Here’s a quick photo of it: https://i.imgur.com/FWE5dr5.jpg. I’ll try and see if the fan connections are all good and actually making contact.


    Quote Originally Posted by blckstrm View Post

    A couple other points of reference since you're new and dealing with a cooling issue. The needle hits 12 o'clock about 175, and starts moving again at 225.

    This is significant because 225 is the boiling point of 50/50 water / coolant mix. So if your system ISN'T holding pressure, that's where you start getting in trouble. Also where you should be realizing there's a problem. You did a great job managing this, by the way. It's exactly what any of the rest of us would have done, too. I don't remember the temps for the upper line and the start of the red zone, but my recollection is that the red zone starts where 50/50 mix boils EVEN UNDER standard system pressure. Thus it's BAD.

    ---

    One last note - I'd stop chasing the cooling system itself. Maybe you'll want to replace the expansion tank if it's original. Maybe your hoses are old and need to be replaced. But if the abuse you just put it through didn't cause any leaks or blow up the expansion tank, you're probably fine to wait on that stuff.
    Thanks for the feedback. It’s good to know at least that I managed it well on that long drive. The temps never hit the 3/4 mark at any point since as soon as they started creeping, I’d turn the heater on to dissipate the heat. The tank seems fine and the hoses, from what I’m seeing, don’t have any cracks or crevices on them for now.


    Quote Originally Posted by Hova View Post
    +1

    People will insist that the front fan does nothing at above 30mph or some made up number, but that's simply not the case. Air is going to flow through the path of least resistance, and through the radiator is not that. A fan will force slower moving air in the front of the car through the radiator well past 30mph. Now triple digits are a different story, but normal cruise speed fans do still do some work.


    Also, you mentioned a Zionsville radiator, does it have a front shroud?
    Yeah it’s the Zionsville radiator and radiator shroud with electric fan. Here’s a pic of it: https://i.imgur.com/FWE5dr5.jpg. The electric fan is spinning but the fan in front of the radiator behind the bumper (this is the aux fan right?) is not spinning at any point.

  7. #7
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    Yes make sure aux fans work properly, but I think you should replace the water pump.

    - - - Updated - - -

    Since your supercharged maybe go with a Stewart pump.
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  8. #8
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    Quote Originally Posted by Eric93se View Post
    Yes make sure aux fans work properly, but I think you should replace the water pump.

    - - - Updated - - -

    Since your supercharged maybe go with a Stewart pump.
    I'd avoid redoing the cooling system until you're sure the obvious things aren't the culprit. If you already have a bunch of Zionsville stuff, there's a good chance you have a Stewart pump already and the cooling system has already been refreshed once.

    Data is your friend. I would get a cheap Elm 327 Bluetooth OBD transmitter and get one of the phone apps to monitor your actual temps. Torque for Android is cheap and great. There are apps for iPhone as well.

    Make sure the main fan turns on when the car gets hot. I assume it's wired to the aux fan switch.

    The aux fan switch works at these temps. It should read about 208 when it comes on low, and should turn on high around 218. If you've had a lower temp switch installed it should start around 194, with high coming on about 204.

    Idling with the hood open you should never see high speed.

    I would not crack open the cooling system until all of the above checks out and you're STILL having problems.

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    So I just took the car to a bmw specialist and they tested it for me and confirmed that the aux fan was inoperative. They used a test fan in place of my fan and said it worked. They also said they pressure tested the cooling system and found a "light drip leak from the thermostat housing gasket" and they recommended that I replace the thermostat, gasket, and waterpump. The fan replacement they quoted me for was a whopping 450 bucks (I think it was an oem one) so I'm going to probably get an aftermarket one. As far as the other components, what do you guys think? Should I also replace thermostat, gasket, and waterpump as well or just the gasket?

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    What water pump do you have in there? If it hasn't yet been upgraded to a Stewart pump or at least a metal impeller pump, yeah it's probably worth doing that too. You're gonna have to drain the radiator and block to do the thermostat/housing anyways, so may as well address any hoses, the expansion tank, or anything else in the cooling system at the same time. Good time to do belts/pullies/tensioners too.
    Last edited by TostitoBandito; 07-07-2020 at 11:13 PM.
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    You don't need to spend $500 on a genuine BMW aux fan the $150 URO one will be just fine.

    I see you don't have a clutch fan anymore...consider upgrading your electric one with a higher flow?
    Last edited by realjones; 07-08-2020 at 12:29 AM.

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    Quote Originally Posted by blckstrm View Post
    I'd avoid redoing the cooling system until you're sure the obvious things aren't the culprit. If you already have a bunch of Zionsville stuff, there's a good chance you have a Stewart pump already and the cooling system has already been refreshed once.

    Data is your friend. I would get a cheap Elm 327 Bluetooth OBD transmitter and get one of the phone apps to monitor your actual temps. Torque for Android is cheap and great. There are apps for iPhone as well.

    Make sure the main fan turns on when the car gets hot. I assume it's wired to the aux fan switch.

    The aux fan switch works at these temps. It should read about 208 when it comes on low, and should turn on high around 218. If you've had a lower temp switch installed it should start around 194, with high coming on about 204.

    Idling with the hood open you should never see high speed.

    I would not crack open the cooling system until all of the above checks out and you're STILL having problems.
    sorry to threadjack, but is it possible to use one of those bluetooth OBD things with the '95 M3 that doesn't have the OBD port in the driver footwell? I still have the round connector in the engine bay though
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    Quote Originally Posted by das borgen View Post
    sorry to threadjack, but is it possible to use one of those bluetooth OBD things with the '95 M3 that doesn't have the OBD port in the driver footwell? I still have the round connector in the engine bay though
    No - no OBD port. 😂

    I have no idea if some kind of adapter would work, or if there is a BMW-specific adapter or transmitter.

    I DO think the car has the data - I just don't know how to get it out. There may be some smarter OBDI guys out there who could help you.

    ---

    As for the new fan, I don't know that I'd go URO, BUT VDO is an OE supplier and you can get a VDO aux fan from FCP for $180. And I'd feel great about that.

    I too wonder what kind of air flow you're getting from the main electric fan. I'm sure the previous owner was less concerned about all this up in Washington than you'll need to be in SoCal.

    I'd look for a model number and see how much air it moves. Zionsville doesn't say which fan they use, but most of the Spal fans I'm seeing move around 1900 CFM.

    The fan I used does 1800 on low and 2400 on high, which I vaguely recall is the same (on high) as the stock clutch fan.

    Obviously you should fix the leak. If your thermostat housing is aluminum, no need to replace it. If it's plastic, it depends on how old it is.

    Thermostats DO wear out, so I'd do that while the housing is off.

    I'd check your records and see how old the water pump is, though if it's not leaking or loose I don't see a reason to replace it unless you want a Stewart pump (assuming it's not already a Stewart pump).

    Who drops $1100 on a Zionsville setup and then just puts in a normal water pump?

  14. #14
    NeilM is offline Member BMW E36 M3 Expert
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    In addition to the good advice already offered by others, I'd emphasize that since this car has a supercharger its cooling needs are greater than stock. Any cooling system shortfalls you might manage to live with on a stock engine aren't going to fly here. Everything's got to work, and work well.

    And given where the OP lives, I'd be thinking about an oil cooler too.

    Neil
    Last edited by NeilM; 07-08-2020 at 03:01 PM.

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    Quote Originally Posted by NeilM View Post
    In addition to the good advice already offered by others, I'd emphasize that since this car has a supercharger its cooling needs are greater than stock. Any cooling system shortfalls you might manage to live with on a stock engine aren't going to fly here. Everything's got to work, and work well.

    And given where the OP lives, I'd be thinking about an oil cooler too.

    Neil
    This is an excellent suggestion.

    And I just realized OP said Phoenix, not SoCal. That's a good 10-20 degrees hotter than here on average (which just blows my mind, frankly).

    Yeah, an oil cooler is a great idea given FI and AZ ambient temps...

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

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    Quote Originally Posted by TostitoBandito View Post
    What water pump do you have in there? If it hasn't yet been upgraded to a Stewart pump or at least a metal impeller pump, yeah it's probably worth doing that too. You're gonna have to drain the radiator and block to do the thermostat/housing anyways, so may as well address any hoses, the expansion tank, or anything else in the cooling system at the same time. Good time to do belts/pullies/tensioners too.
    No clue about the water pump, I’ll have to look through the service records to see if I can find it. The rest of the cooling system is replaced with the usual recommendations including an aluminum thermostat housing so hopefully the water pump is a Stewart one. When I take the cooling system apart this weekend I’ll let you guys know.

    Quote Originally Posted by realjones View Post
    You don't need to spend $500 on a genuine BMW aux fan the $150 URO one will be just fine.
    I see you don't have a clutch fan anymore...consider upgrading your electric one with a higher flow?
    I’ve heard bad things about URO and good things but mostly bad. I’ll probably go withe VDO or ACM.

    Quote Originally Posted by blckstrm View Post

    As for the new fan, I don't know that I'd go URO, BUT VDO is an OE supplier and you can get a VDO aux fan from FCP for $180. And I'd feel great about that.

    I too wonder what kind of air flow you're getting from the main electric fan. I'm sure the previous owner was less concerned about all this up in Washington than you'll need to be in SoCal.

    I'd look for a model number and see how much air it moves. Zionsville doesn't say which fan they use, but most of the Spal fans I'm seeing move around 1900 CFM.

    The fan I used does 1800 on low and 2400 on high, which I vaguely recall is the same (on high) as the stock clutch fan.

    Obviously you should fix the leak. If your thermostat housing is aluminum, no need to replace it. If it's plastic, it depends on how old it is.

    Thermostats DO wear out, so I'd do that while the housing is off.

    I'd check your records and see how old the water pump is, though if it's not leaking or loose I don't see a reason to replace it unless you want a Stewart pump (assuming it's not already a Stewart pump).

    Who drops $1100 on a Zionsville setup and then just puts in a normal water pump?
    I looked up the VDO aux fan and the reviews of it on FCP euro are not that positive. I read that ACM fans are good but I’m seeing them as low as 112 at AutohausAZ, is that the same fans they’re talking about here: https://www.bimmerforums.com/forum/s...termarket-unit ? They mention that it’s pricey but it doesn’t seem like it anymore.? As for the electric fan you’re running, could you let me know which one? If I’m running a weak one I’d like to replace that as well. The specialist said that the aux fan being inoperative was slowing down the electric fan as well. Once they installed the tester, he said that both were running fine. Does that sounds about right?

    Quote Originally Posted by NeilM View Post
    In addition to the good advice already offered by others, I'd emphasize that since this car has a supercharger its cooling needs are greater than stock. Any cooling system shortfalls you might manage to live with on a stock engine aren't going to fly here. Everything's got to work, and work well.

    And given where the OP lives, I'd be thinking about an oil cooler too.

    Neil
    I want to get an oil cooler but I just don’t think there’s enough room for one. The intercooler takes up the spot in front of the radiator where the cooler would have sat. Any suggestions about this?

    As far as the thermostat what do you guys think I should get? 75c, 80c, or the stock 88c? I’m leaning towards 75 or 80c but I’ve been reading things that the 75c thermostat might not let the car get hot enough. Do you think that would be an issue in Phoenix?

  17. #17
    NeilM is offline Member BMW E36 M3 Expert
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    96 M3, 15 Golf R, 18 Q5
    Quote Originally Posted by pasllani View Post
    I want to get an oil cooler but I just don’t think there’s enough room for one. The intercooler takes up the spot in front of the radiator where the cooler would have sat. Any suggestions about this?
    One option would be the Euro E36 M3 oil cooler setup, where the oil radiator attaches to and hangs directly below the coolant radiator. In our US cars there's a plastic baffle occupying that space to prevent air from bypassing the radiator. Downside of the Euro option: not inexpensive.

    Turner has a version that'll work with superchargers:



    See: https://www.turnermotorsport.com/p-1...ro-oil-cooler/

    There may be other options, depending on how much room your IC takes up.

    As far as the thermostat what do you guys think I should get? 75c, 80c, or the stock 88c? I’m leaning towards 75 or 80c but I’ve been reading things that the 75c thermostat might not let the car get hot enough. Do you think that would be an issue in Phoenix?
    Stock 88C.

    Your cooling ability under high demand conditions — which is the only time it matters — is determined by the physical capacity of the cooling system, and is independent of the t'stat calibration. (That's assuming your t'stat is working properly, of course!) In practical terms this means that when you're pushing the car hard, all of those t'stats will be wide open all the time.

    Neil

  18. #18
    Join Date
    Jul 2011
    Location
    Austin, TX
    Posts
    2,181
    My Cars
    S54 E36 M3, E32 740il
    My fan is a Derale 18217. It was like $135 on Amazon.

    My thermostat is stuck open, and it can trigger a CEL in the winter if it gets below about 45 and stays there for more than a few days. But it's been a couple years and I haven't had that happen (though I did get a cat inefficiency code twice this winter).

    But as long as you're not getting your inspection at that time of year, I'd rather run cooler than hotter.

    Unless I move somewhere much colder I'm not worried about it (being recently laid off, that may be sooner than later).

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  19. #19
    Join Date
    Jul 2020
    Location
    Surprise, AZ, USA
    Posts
    41
    My Cars
    1999 BMW M3 Coupe
    Quote Originally Posted by NeilM View Post
    One option would be the Euro E36 M3 oil cooler setup, where the oil radiator attaches to and hangs directly below the coolant radiator. In our US cars there's a plastic baffle occupying that space to prevent air from bypassing the radiator. Downside of the Euro option: not inexpensive.

    Turner has a version that'll work with superchargers:



    See: https://www.turnermotorsport.com/p-1...ro-oil-cooler/

    There may be other options, depending on how much room your IC takes up.



    Stock 88C.

    Your cooling ability under high demand conditions — which is the only time it matters — is determined by the physical capacity of the cooling system, and is independent of the t'stat calibration. (That's assuming your t'stat is working properly, of course!) In practical terms this means that when you're pushing the car hard, all of those t'stats will be wide open all the time.

    Neil
    I was looking at this setup but when I took a closer look at my radiator, looks like it was replaced by a Mishimoto radiator w/o the hoops for mounting this style of oil cooler. If I do go this route, over the next couple months I'll end up building my own kit piece by piece for that oil cooler rather than paying the premium some of these companies charge for the full kit. Should cost around 800 bucks if I piece it together myself. As the for brackets to hold up the cooler without radiator hoops, I was not able to find anything online about mounting this to a radiator without the supporting mounts, do you guys have any references I could take a look at for this?

    Quote Originally Posted by blckstrm View Post
    My fan is a Derale 18217. It was like $135 on Amazon.

    My thermostat is stuck open, and it can trigger a CEL in the winter if it gets below about 45 and stays there for more than a few days. But it's been a couple years and I haven't had that happen (though I did get a cat inefficiency code twice this winter).

    But as long as you're not getting your inspection at that time of year, I'd rather run cooler than hotter.

    Unless I move somewhere much colder I'm not worried about it (being recently laid off, that may be sooner than later).
    I was looking at the Derale 18217 you mentioned but it looks like its a bit too thick to fit in my set up. The fan I currently have is SPAL VA18-AP51/C-41A which has a maximum output of 1400 cfm and is only 2.5 inches thick. So I went ahead and pulled the trigger on a replacement fan from Flex-a-lite model 104358. This fan is about 3/4 inch thinner than the Derale fan you have so I'm hoping I'll be able to fit this a bit better. Plus its also rated at 2500 cfm and the reviews for this fan are great everywhere I'm looking. My only worry is the mounting points for this. Might have to drill new points on the shroud.

    Quote Originally Posted by TostitoBandito View Post
    What water pump do you have in there? If it hasn't yet been upgraded to a Stewart pump or at least a metal impeller pump, yeah it's probably worth doing that too. You're gonna have to drain the radiator and block to do the thermostat/housing anyways, so may as well address any hoses, the expansion tank, or anything else in the cooling system at the same time. Good time to do belts/pullies/tensioners too.
    I was looking through the service record and I think it has a Stewart Water pump. The record says they installed a Stewart water pump "kit" so I'm hoping and assuming it came with the pump lol.

    ----

    When I took the cooling system apart yesterday we removed the coolant level sensor since it was always saying the coolant level was low and we found it was caked is a thick silver glittery sludge. Really weird and has me kind of worried about the other parts. I wish I had a photo of this but we rinsed it before we even thought about taking a photo of it. Have you guys ever heard or seen this?

    I also ordered a new thermostat, coolant level sensor, housing gasket, o-ring for sensor, bmw coolant, and vdo aux fan which should be here tomorrow. The electric fan doesn't arrive till Sunday so I'll probably wait till then to install everything. Thank you guys for your suggestions and help! Saved me a lot of time and money so I really do appreciate it.
    Last edited by pasllani; 07-15-2020 at 10:45 PM. Reason: Quote did not go through

  20. #20
    Join Date
    Jul 2011
    Location
    Austin, TX
    Posts
    2,181
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    S54 E36 M3, E32 740il
    The fine slivery glittery stuff was in mine, too. I don't know what it is - whether it's some kind of precipitate from the coolant itself or from the float in the coolant level sender decomposing. I didn't worry about it too much and haven't had any trouble. It didn't (on mine) seem to be enough that it could have caused any kind of blockage or other problem.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  21. #21
    Join Date
    Jan 2019
    Location
    MI
    Posts
    128
    My Cars
    1997 BMW M3 Sedan
    Quote Originally Posted by blckstrm View Post
    The fine slivery glittery stuff was in mine, too. I don't know what it is - whether it's some kind of precipitate from the coolant itself or from the float in the coolant level sender decomposing. I didn't worry about it too much and haven't had any trouble. It didn't (on mine) seem to be enough that it could have caused any kind of blockage or other problem.
    Add me to the list for the glitter in the coolant. I replaced my coolant right after I purchased the car and found the same stuff. No pin hole leaks I could find (thought it was maybe stop-leak), and when I refilled the system I didn't have any leaks anywhere. Previous owner replaced all the hoses and a put in a stewart water pump and AL thermostat housing.
    Last edited by Cos270; 07-16-2020 at 12:23 PM.

  22. #22
    Join Date
    Jul 2011
    Location
    Austin, TX
    Posts
    2,181
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    S54 E36 M3, E32 740il
    Quote Originally Posted by Cos270 View Post
    Add me to the list for the glitter in the coolant. I replaced my coolant right after I purchased the car and found the same stuff. No pin hole leaks I could find (thought it was maybe stop-leak), and when I refilled the system I didn't have any leaks anywhere. Previous owner replaced all the hoses and a put in a steward water pump and AL thermostat housing.
    I've never used anything besides factory Coolant and water, and have replaced everything at this point. So it must either be plastic decomposing or something precipitating out of the Coolant. Either way I'm not terribly concerned.

    I'm more concerned that my phone keeps capitalizing "Coolant."

  23. #23
    Join Date
    Jul 2020
    Location
    Surprise, AZ, USA
    Posts
    41
    My Cars
    1999 BMW M3 Coupe
    Hey guys I have an update and it's NOT good.

    So we replaced the aux fan with a VDO one and it works fine now. Turns on when A/C is on and everything. We couldn't quite fit the Flexalite fan since there isn't enough clearance between the waterpump pulley and the fan motor shroud.

    We replaced the aux fan, the coolant was replaced with BMW and distilled water 50/50 and it was bled for about 10 mins or until a solid stream of coolant came out of the upper hose, the thermostat was replaced with a Mahle 88c one, the thermostat housing gasket was replaced, the water pump was removed and inspected and it was a Stewart water pump in immaculate condition (no signs of wear whatsoever), and the original Spal 1400 cfm fan was running well. The Mishimoto radiator looks new so I don't think there's a problem with that either.

    It was still beginning to overheat when the car runs above 2.5k rpm for an extended period of time with the A/C on full blast to test it's durability. When it came to a stop, the temps now began to fall unlike last time so that's a plus I guess. But now I feel defeated after spending nearly two weeks with the car on jacks and have no clue what it could be. Could it be the electric fan? The radiator? Could it be the coolant mix (should I use only distilled with water wetter)? Could it be the intercooler not functioning properly (how would I even test that)? Could it just be too much heat in the engine bay causing heat soaking?

    Any clues or suggestions at this point would be extremely appreciated. Thank you guys.

  24. #24
    Join Date
    Jul 2011
    Location
    Austin, TX
    Posts
    2,181
    My Cars
    S54 E36 M3, E32 740il
    Someone just resurrected an old thread of mine where I did my electric fan install into the factory shroud, and I made some observations on temperature there.

    https://www.bimmerforums.com/forum/s...0#post30515140

    Are you monitoring your temps via OBD? You can get a cheap bluetooth transmitter and there are apps for both Apple and Android.

    What was ambient when you did your test?

    Also, what does your ducting look like? If the air can get around the radiator, it will.

    My intake air temps can get super high - like 150 - idling in traffic, and stay higher than I'd expect when driving (135 or so) when it's really hot outside (105-110 on the OBC). And I'm NA. I'd assume you're in worse condition running FI.

    Living in AZ with FI, you will probably have to get an oil cooler. Your intercooler probably IS working. That's probably part of the problem - it's pre-heating the air going to the radiator.

    You may also need to vent your hood to get that hot air out and avoid heat soak. I've been contemplating vents for a long time, but I'm looking for a nice hood from a junkyard car so I'm not cutting up my own original hood.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  25. #25
    Join Date
    Nov 2002
    Location
    Washington, DC
    Posts
    6,481
    My Cars
    E30 E36 E46 E90
    So, have you considered installing an S54 MZ3 radiator in place of the garbage Mishimoto?

    Edit: Also, if you're having trouble with cooling with an electric fan installed, why not try a mechanical fan?
    Last edited by nick325xit 5spd; 07-20-2020 at 11:31 AM.
    2011 M3 Sedan
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    Hers: 1996 Porsche 911 Turbo
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