Hello Gents. I'm Chad, my forum friends call me Chaddict. I just sold my stage 5 02 540 cause it broke 100k and bought an 02 Nicely loaded TiAg M5 with 144k. Nastydipped wheels, sun shades, PDC, m audio, alcantara headliner, muffler delete, and a SAP code that made it 251 miles since my purchase Friday until coming on this morning at cold start. The rear sun shade won't come up the motor just runs, the aux fan isn't running when a/c is off and the car is idling, otherwise drivetrain and interior is solid. Nonetheless needs suspension and cooling system overhaul, but overall its not reflective of what I paid. The hood and both passenger doors have been repainted and it looks decent but not good enough to leave. I tried power washing the plastidip off but no dice so I threw my staggered M66's on with solid rubber to get the 65's coated. The car was so dirty inside and out I dropped it off this morning for a expensive new car store detail, which it needed bad I had to wash my hands after driving it. I went to pick it up but the paint was still nasty and so I asked them to do the higher platinum level detail. When I went by the car was sitting idling and I couldn't hear aux fan, checked gauge and it was 7/8 up, test no. 7 revealing 118c coolant temp. Anyway I am picking the car up tomorrow and taking to DUDMD my local tuner to have sap coded and everything else checked for working order and concerns. These things I am familiar with it's the drivetrain I'll need you guys to walk me through, as I am familiar with M62 and S85, but first S62 and I need your guys help. My name is Chad. I won't go nuts hopefully and bother you guys I just bought an M5 that needs some love and pampering and I can't manage without lots of help .
Thanks and please introduce yourselves as you reply so I can try and keep up.
When I bought Friday
I magic erased the chipping nasty disgusting wheel to a moderately ok finish Saturday
Then a couple videos of having fun. God I love the e39 chassis with a manual 420G and a 3.15 LSD (3.46 or 3.64 planned)
The car today with a partial crap detail and overheating.
I hope to become a part of this community of you guys will have me. I kind of like the 66's but it's only temporary while I get 65's refinished. We'll See what else the car has in store for me. I hope at 144 I can bring it back. The motor pulls amazingly and it is a great platform as most everything is in tact and works. Thanks fellas.
Welcome to M5B Chad and congratulations on the Beast. I've been following the thread you have on the other site. Let me know how it goes with Dima and the SAP thing. I might need his help on that too. I am also curios to know if he has developed a performance tune for the S62.
Think you'll need to thoroughly investigate the cooling system or all is going to be for naught as they say. Your car is similar to mine (an '02, currently at 134k miles) and I've been working on it steadily since buying it about 10 months ago. If I were you I'd do a complete coolant service using BMW coolant and probably change the thermostat too. Inspect the engine-driven fan clutch, accessory belts and check function of the electric fan. Some here might also be leaning toward a new water pump. I'd also do an oil change, maybe even taking off the lower cover to see if there's sludge build-up. I've got a recent DIY posting on radiator change with some pictures that may be of help. If you can get the overheat issue sorted then it's the basics - transmission and diff fluids, spark plugs, fuel filter. Lots of good DIYs posted here for help.
Welcome! With the temp that high, I would assume the aux fan and fan clutch are both shot and/or you have some major cooling system failure. Definitely make it a priority. Overheating typically doesn't end well for cars with aluminum heads/block.
While some around here would call it unseemly, I ordered a TYC Aux fan from Amazon for mine. It's been in since January with no problems. It is stupid loud, but from what I gather so is the OE BMW fan.
While the Bentley manual doesn't cover the S62, the following quotes could be useful general info:
P. 170-4 Electrically heated thermostat
"The electrically heated thermostat is DME map-controlled. The engine control module (ECM) activates the thermostat to maintain coolant temperature within a narrow range.
In case of failure of the electronics, the mechanical function of the thermostat acts as a fail-safe."
P. 170-5 Electric (auxiliary) cooling fan
"In models manufactured after 9/1998 (M52 TU engine, M54 engine, M62 TU engine), the electric cooling fan is controlled by the engine control module (ECM) via the output final stage.
The output final stage is mounted on the fan housing, next to the fan motor. The fan is operated using a pulse width modulated signal. Fan circuit wiring is protected by a 50-amp fuse..."
Again, though Bentley doesn't cover the S62, I'm thinking that this info is same for the M5 cars. Maybe some of the more knowledgeable members here can verify.
Thanks everyone. The car had been sitting outside idling for an hour or so, and I hope that 118 deg c won't desperately hurt anything but the aux fan was definitely not running. Replacing the thermostat, lower coolant temp sensor, and clutch on primary is definitely first on the list. Dima is going to mess with SAP today I'll have him look over cooling system. I will run the air conditioning when I pick the car up from detail and see if aux fan runs and car stays cool. My 540 would run at idle anywhere from 103 deg to 108 deg c so should I assume similar temps as normal or should the S62 run cooler?
I suppose it depends on your intended use, but I have driven cars with a 3.46 and a 3.64, both with muffler deletes. I found them to be too loud on the highway, and too much work to drive in traffic. 1st gear was shorter than I found comfortable with the 3.46 and 6th gear left the revs too high at 70mph. But, I mostly use my M5 on the highway where I like 6th to be my "silencer" gear.
I think the general philosophy for the S62 was to gear it long and use the low-end torque to accelerate the car. The 3.64 I drove ran out of revs too quickly for a V8, in my opinion.
I know the radiator and temp sensor for the DME is good. The radiator is a 2014 German behr I think the aux fan not running and the car idling for an hour is what got temps way up. The clutch fan at idle isn't spinning fast enough to do much cooling and without an aux fan to keep temps at basically 95-100 c the temp just slowly climbed for an hour. Those temps are crazy hot, but in normal driving they were not really higher than 95 deg ever. I pick the car up in a couple hours and I'll test the aux fan and see what's what.
I am torn between shift knobs. Since its illuminated I was thinking F10 M5 knob but the leather boot has to be stretched and retrofitted over e39 console and can get tight when going to 6th. I can also order the standard leather M5 long handle but it's still long AF, or a simple unlit ZHP knob. The ZHP knob is 6.3 ounces and the F10 is 6.0. I like the backlit idea but weighting and feel is more important, not to mention $100 price difference. Any input?
The aux fan keeps the coolant temp in the range 79 to approximately 95C. When the air flowing over the fan clutch gets to 95C (so I guess the coolant in the rad has to be a bit hotter), the clutch engages and drives the big fan. The clutch stays engaged down to about 85C.
There would be no air flow during warm-up at idle with the aux fan being NFG, but I would have expected the normal slow rotation of the disengaged clutch fan to have pulled enough hot air to engage the clutch at 95. Obviously, yours didn't when the temp got up to 118, so either the clutch is bad or maybe the rad is plugged with debris which is pretty common.
Apparently, Chad and I are experiencing a similar problem here.
First time I noticed mine overheating was back in mid June, just a week or two after purchasing it. I was on my lunch break from work and was sitting with engine idling and the a/c running. It wasn't long before the a/c had then cut off and a moment later blowing in hot and humid air. Didn't notice the gauge if it had started moving to the right from its exact 12 o'clock position. Then I decided to give some gas in the hope of the mechanical fan would blow in air through the radiator and the condenser. In order to dissipate the heat and bring down the a/c pressures and the compressor kicking in one more. I held the throttle for a couple of minutes and just above 1k rpm. My a/c started working once again and was getting cold air in, when moments later, yet again, it disengaged, blowing in hot air one more time. It was at this time when I quickly noticed my temp gauge slowly creeping to the right. I don't remember what my Test 7 readings were but it didn't matter as I had quickly shut off the engine, rolled down the windows, and sat there for some time to cool it off.
On my 530i, upon a cold start the aux electric fan comes on for a few seconds as a system check. It won't run again not until the radiator outlet temp will reach within the normal operating range. Turn on the a/c and it comes ON which again is all normal and functioning properly. This isn't happening on the M5, however. Upon cold or hot start, the aux fan doesn't even budge. Turn on the a/c and it still won't turn over. My a/c works fine but only when I'm moving at speed, city or highway, which makes sense since air is being blown past the condenser + radiator; keeping the temps and pressures under control. At stationary, if I leave the M5 running for way too long, it will start to overheat. I've seen it getting up to 105-108C before I shut the engine off. At normal cruising speeds, city or highway, I'm seeing engine temps around 86C +/- here and there. This tells me that at least my thermostat is working and doing its job properly. Therefore, this could possibly mean few things. My radiator outlet temperature sensor mustn't be working. Possibility that the aux fan isn't getting 12V. I will have to check and verify that. And since this is PWM, I'll have to figure how to apply voltage to run the fan/motor and see if the motor is fine, if not then that concludes everything. Check the ground(s) too.
Anybody know if BMW like to use NTC or PTC temp sensors?
My modified M62TU has an 88 deg. thermostat and never, ever runs as hot as your stock M5 above, and you have a 77 deg. thermostat. Something's very wrong and I wouldn't drive the car until it's fixed. That's just too hot.
B - I think I'll grab the extra fan clutch sitting in yer office if ya don't mind. How many miles on it? Yer sure it's in great, working condition? I might replace mine with yours just for the sake of it.
My modified M62TU has an 88 deg. thermostat and never, ever runs as hot as your stock M5 above, and you have a 77 deg. thermostat. Something's very wrong and I wouldn't drive the car until it's fixed. That's just too hot.
NO aux fan (primary cooling mechanism) and fan clutch probably old and failed = overheating. I wouldn't drive it anywhere if it got to this temp just sitting there. I never see my coolant over 91C in 105+F heat temps. My oil temp hasn't crossed the line either. Your aux fan should have come on, however. The fan clutch doesn't operate until air > 92C crosses the radiator, which it can't if it's just sitting there and no aux fan is running.
The mechanical fan is the primary air moving device. I know everyone will jump in and tell me how wrong I am in just a moment. But I am not. If the engine is spinning, the water pump fan is moving air. Just like any vehicle with a crank driven fan this is the primary air mover. As temps rise the clutched connection slips less and less and moves more and more air. There is not some magic number where it just engages. It's infinitely variable. If the clutch is worn there will be more slip and less air moved than designed. Certainly check the mechanical fan clutch as well.
The electric fan is primarily there to move air during low vehicle speed and to help air conditioning condenser efficiency.
My feeling is this is a combination of a questionable thermostat and an inop aux fan. The aux fan wasn't running but a permanently closed thermostat means the radiator is cool enough the sensor in the radiator controlling aux fan isn't picking up the excess temps the DME temp sensor is picking up and thus not turning aux fan on. I'll start by seeing if AC use runs aux fan and if it does I'll replace both the thermostat first. If the thermostat doesn't fix it I'll replace the lower radiator coolant temp sensor. 118 is super hot. even without the aux fan the circulation on its own should keep temps at 105-110. I have a feeling the temp is only up on engine side. If the thermostat IS good then it's probably a combination of bad aux fan and mech. Fan clutch.
I think you are going about it in the right order. Your aux fan is toast. Your fan clutch may also be bad. I can let my car idle all day in south Florida and I never see those kinds of water temps.
Tstats generally fail in the open position, not closed. Once warm, check your hoses. If hot, you have water flowing and the tstat is open (or at least partially open).
As suggested above, I would do a good clean around the rad and condenser, lots of junk can build up affecting airflow. Coolant/water should be changed every 2-3 years. Easy to swap coolant IF you are not going to do a tstat swap; if so, obviously, do it after you install the tstat (I say after because often there will be leaks at one of more of the O rings from the coolant pipes; no sense wasting fresh coolant until you confirm no leaks).
I will check hoses for heat and let car idle to see how the temps increase and what runs either on the mech. fan or aux fan side. The car is at the deaer for detail so I don't know how long it was sitting there idling or any other parameters so right now I just know it did overheat but not how/ why. Once I pick car back up I'll be able to diagnose what's the source and what's working and not working. Thank you guys this is awesome the plethora of information. My last question is can 118c hurt anything I should double check? I know it's not a meltdown temp as my my M62 ran. At 108-109 all the time, but is there anything that 118 can cause harm to?
Again how can I edit my previous posts from mobile?
Also I wanted to ask a question about the servotronic. It's my first servo e39 and it kind of hums a tiny bit at a high pitch. Not loud enough to hear unless radio and everything is off just very slight hum when you make steering inputs. I doubt it's ever been flushed.
Bother to check the PS fluid? Make sure you use the right kind, Owners Manual calls for ATF.
As to 118C, one thing at risk is your AC compressor. Your high pressures are going to skyrocket if you let the car idle with those temps. So you run the risk of blowing your compressor. On the highway, you have enough air flow to turn the AC back on.
Not sure what else 118C does (warp the head???, don't think that is high enough, but I don't know, but possibly blow a head gasket?), but if it was good for the car, I assume the BMW engineers would let it get that hot on purpose!:devil
Just to make you happy, that is not right. The electric is primary and is completely variable with a second function of drawing air thru the AC condenser. The mechanical appears to start to engage the clutch at 92c and is completely engaged at 95c. Just because the fan is spinning does not mean it is moving air or at least a decent amount of air. With the drag on the fan from the clutch it does spin, but it may not be enough to overcome the air drag and actually move air. That fan can be stopped fairly easily, and I would bet the fan speed increases with ground speed which would indicate it is hanging in a neutral air flow.
You are disagreeing with physics, fluid dynamics and automotive engineering not me...
If a fan is spinning and its not in a vacuum (these are not space ships) then it is moving air. I will describe each fan and then you guys can argue over semantics.
- One spins all the time, has the capability to move huge huge quantities of air, moves more and more air with increases in temperature, and is integrated in the same manner and LOCATION as 99% of the liquid cooled vehicles ever made (I cannot think of any examples of conventional front mounted longitudinal engines that don't have a fan BEHIND the radiator but there may be some odd balls).
- One spins some of the time, can move a reasonable amount of air (far less than the fan described above), and is controlled in a way that it assists with air movement at low road speed or engine speed or at high AC pressure/high condenser temperatures, and it is on the opposite side of a "typical" fan found on road vehicles. Also its called an AUXILIARY fan...
Well hopefully my hvac pump isn't fried cause now my interior blower motor is squeaking in my vents inside. Never did that before the detail. Went to borrow scan tool from local parts store and the dark blue Bosch tool couldn't communicate with DME to pull codes so aside from them accidentally undercharging me on detail everything else appears to be a total nightmare. Temps aren't getting above 89 c and as low as 81c. I have let the car sit and idle and it's maintaining 84 deg c but right now I just need to contemplate 1) why are suddenly the interior vents making this terrible noise 2) why is the scan tool not communicating after several attempts and 3) (update) why is it only making the nasty noise through the vents with the a/c on.
So the nasty noise is ONLY with AC on. When I turn AC off its normal. Also the car with AC off cooled does to 82c but with AC on the temps warm up a few deg c.
Now for another update I turned the AC back on and noise has not returned and it's back to normal. Hmmmm odd.
You are the one who is disagreeing with physics and you seem to be creating your own. It is not called an aux fan by BMW although they call others aux. It is called an electric fan. BMWs other cars don't work this way. Most of the other fan clutches have a much wider engagement range and start as low as 75C.
You are playing word games and being an English prof. In fact on this car there is not a primary nor an aux. We have an electric finesse fan which is sensitive and tries to start cooling the coolant as soon as it sees possible temp gain. Then we have a bull fan that blasts air when the finesse fan has failed to dissipate the heat generated, but it waits until there is no chance for the finesse fan to recover.
Since the electric has first shot at the game we call it primary right or wrong. That is the english or language used on the M5 board. You can call it what you want as long as it is not secondary.
Who said vacuum, you did not me. You said it spins so it must be pushing air. Wrong, that only happens in a vacuum, but then again nothing to move in a vacuum. It boils down to how much energy is sent to the fan minus the air drag equals the energy of the moving air in relation to the ground speed or wind speed. Do you have any idea how much drag a fan blade has? One sign that it is beating drag is noise.
Forget I called it an Aux fan then. Both just fans.
The only physics I meant to imply in the whole post was that a spinning fan is moving air. The engine driven fans spins 100% of the time that the engine is running. Unless that fan is in a perfect vacuum it is moving air... No if, ands or buts.
You are the one twisting words with "finesse" and "bull".
I will leave you with this, if you could only have one fan, which would you choose? You get to remove one and keep one. Which allows the engine not to self destruct under normal conditions for this car (which could include daily driving in traffic or a race track)? I'll take the engine driven fan and remove the electric fan. Thanks.
Anyway. Not the place to discuss. Just trying to help the OP.
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