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Downside of going to full electric cooling fans ?

37K views 162 replies 19 participants last post by  AseanAero 
#1 ·
We're considering going eliminating the standard fan clutch and fan and going to full electric cooling fans and custom aluminum radiators for our 3 M5s (and my E34 M60) here in Jakarta.

Has anyone done this ?

My main concern is electrical load, adding another 35 amps to an already heavy electrical load in the M5 , particularly at night.
 
#2 ·
Sample aluminium radiator

Taffy had a sample radiator made up for GA25331 , standard size.

I think the local shop did a good job

We'll look at design improvements for the later batch of radiators once this one is installed and tested in GA25331.
 

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#3 ·
That looks like a really nice fabrication job on the radiator. Is this a 4 core?

I have test fitted those potent Sierra Cosworth fans, and they will work perfect on the M5 radiator when you turn the whole fan shroud assembly upside down.

On the V8, my friend used an 850 (T5 variant - I think) volvo 2 speed fan, and it works perfect. Almost never even gets to its high speed. But the Volvo one will not work on the M5
 
#4 · (Edited)
Besides a slight weight penalty with having a capable enough fan vs the viscous unit there really aren't many downsides besides as you mentioned the additional current draw. If you trigger the fan correctly you can also eliminate the auxiliary fan which helps offset some of the added weight and reduces restriction. My route includes a larger alternator due to a few other additional loads but I'm doing essentially the same thing with a larger radiator and E60 M5 electric fan I picked up from BMW a couple years back.

Greg
 
#5 ·
The viscous unit increases with engine speed of course so is giving a little feed forward control, whereas the electrical fans are purely reactive. +1 to the comment on power, you can pull a lot of air with the engine driven fan.

W.r.t the radiator if you are a normal driver (as opposed to a racer) then you want the cooling balanced to the engine. Over cooling means your stat will be in a less open position and if you do have a sudden tip in event the lag in the response could create temperature overshoots.

Is there a problem with the way the standard system is performing for you guys?
 
#6 · (Edited)
Problems

Fan clutches

High rate of failure of the fan clutches , as part of the overheat teardown I found the fan clutch on my M5 (GA25324) wasn't working properly when I tried it out on my M60 where the fan clutch had also failed.

We're finding that the BEHR fan clutches (not the cheap ebay ones) are not working like there supposed to , I have a brand new one now on the M60 V8 and sometimes it will cut out at 3,000rpm (should be 2,550rpm) but 50% of the time (when it's really hot) it locks up and starts wailing at high rpm (I back off at 4,000rpm to stop the fan grenading) or they're not moving the correct volume of air at idle

Between the 2 x E34 M5s, E34 M60 and E30 M3 (as a group of 3 owners) we've chewed through at least 5 or 6 fan clutches in the last year.

I've totally lost confidence in the fan clutch set up.

Top radiator hoses

Taffy has blown off the top radiator hose on GA25331 at least 3 times that I can remember (Taffy ?), on my GA25324 the top radiator hose also blew off resulting in a warped head in spite of normal water temp and oil temp readings when it happened (low coolant alert went off 2 mins after the engine was shut down)

That's why we want aluminum radiators with proper hose neck fittings , the hoses are either blowing off or the plastic radiator necks are failing

Indonesia isn't much hotter/humid than Florida but we can get stuck in very bad traffic for hours at low speed and the standard cooling systems aren't handling it

One of the biggest problems with the E34 M5 in Indonesia is overheating , not just our M5s but all the owners we've spoken to.





Track Days

Within 3 laps of the 4km circuit the engine oil temp is 120 deg C although water temp is showing normal (in the middle) but then the top hose blew off in the pit area (twice)
 
#9 ·
In my view the extensive use of plastics in the cooling system is a big mistake by BMW for the S38 and the M60 , I guess 20+ years from production we are well outside the design life of these components (15 years ?)
 
#45 ·
Actually it is measured in hours!!
Something like 1500 hours at 210 deg.F, that is 62 Days or 60k miles at an average speed of 40 MPH.

I know 210 deg.F is hotter than the M5 thermostat @ 175 deg.F however that is the temp used in the testing and it is all we have so far and I anticipate the results may not be that much different.

So the next question not dealt with is how does the typical vehicle usage temperature cycles affect the plastic aging process.
My guess, it accelerates the failure processes!!

PA66-GF25 (embossed in the side of the BMW radiators) glass reinforced nylon was tested by DuPont in the attached 2010 paper and at 210 deg.F and it degrades to 60% of its initial tensile strength when exposed to 50/50 mix of ethylene glycol. After 3000 hours it is down to something like 25%!!!

For me, it means the radiator and other plastics exposed to engine/coolant heat must be in the preventative maintenance program or at some point the vehicle will experience a catastrophic cooling system failure, like the radiator neck breaking off or the inlet tank cracking opposite of the radiator inlet due to the higher temp and pressures at that part of the cooling system circulation loop.

I have settled on 75k miles (should probably consider age at some point, as a or what ever comes first, 10-15 years is a good point) just because that interval is not to excessive and by the time you have installed the 2nd radiator after the original, your over 150k miles or 20-30 years. Certainly, the radiator failures I am aware of have all occurred at beyond 75k miles and there is little saved to extend it to 100k miles and the risk of failure will go up in multiples every 10k miles beyond the 75k mile point.

Unfortunately, the plastic engine, radiators and other cooling system components have been prevalent in the automotive industry for over 30 years.

You can assume it is something you will have to deal with since even if you install an all aluminum radiator there are other parts in the engine bay that are subject to the high heat cycles that will fail as the vehicle ages like the heater control valve and motor, fan blade, etc.
 

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#10 ·
I think it's the higher pressure you guys in exotic climes have to run. My car is 21 years old, used virtually every day for the last 11 years and with 200,000 miles and no plastics issues to speak of.

In fact, the fully aluminium thermostat housing and return ducts could be done in plastic nowadays and I'd be fine with that.

The rad end tanks are plastic, but the ribs they have on the spigots make the joints very secure as long as the hoses aren't stiff from lack of use. That'd be a problem regardless of the spigot material.
 
#11 · (Edited)
I think your problems are pressure related, which is driven by temps.
if the parts could be relied upon then the current setup should work in 1990 road traffic, but, nowadays it's different.

my own car temps are completely stable and predictable now following OIL thermostat change... everything else I did had almost no impact, that one part has revolutionised my car's temps

don't want to teach you to suck eggs, I mean, look at your workshop and projects, you know your stuff!.. but I would do these things :
- design your electrical cooling system with a huge amount of EXTRA cooling capacity - overcooling will be a NICE problem to work on / have....
- have a failsafe MANUAL on/off (modern electronic thermostats, and their placement, are not 100% reliable!)
- examine the MTBF of the fans
- use new wiring as E34 wiring is often old and brittle

ALso, what about replacing the water itself to reduce pressure?

see the stuff these guys do.. http://www.evanscoolants.co.uk/technical/no-water-no-problems/72

from their site
Water generates high vapour pressures as its temperature increases – approx 1 Bar (14.5psi) at 100˚C. These pressures exert internal stress on all cooling system components, especially hoses, pump seals and radiator seams. When the engine cools the pressure reduces. i.e. the process is cyclical and repetitive, which often leads to fatigue and component failure. E.g. burst hoses and burst radiator seams - See more at: No Water No Problems
 
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#12 ·
huge amount of EXTRA cooling capacity
Use very large heater core, so when over heating is possible just turn heat on and ~10 litres cold water rush into engine. You dont have to take heat into cabin, you have red-blue dial in center vents. So keep it blue and cold air is coming in but water circulate through heater core.

Or, because you dont need heater at all (unless you visit here someday) you can make extra cold water reservoir into trunk. Extend heater hoses long enough. However that reservoir will never cool down in your climate...

ouich
 
#14 ·
Holly crap! Jakarta seems to be terrific hot...I guess there is no winter weather over there never ever :) Lucky me the highest we could see here is probably 35º C for short period of time and average is arround 20ºC. Anyways, the M5 already have a big radiator and fitting a larger one will be a though job, maybe more cores or just a bit thicker. In the other hand, would you mind exploring the possibility of use a custom COPPER radiator? Back then, the Jeeps we used to sell and service, used copper radiators and then, they decided to change to aluminum (cheaper), which is not bad move, but copper used to keep the temp bit coole rover aluminum.

In the other hand, add a extended engine oil cooler/radiator, keeping the oil cooler help overall the engine to stay, well, cooler and protect it. For the heater core, you have the option to modify the HVAC and fab a air vent tube to blow the heated air outside of the cabbin somehow when you see too much heat in the day or tracking the car, this of course if you never use the heater in all the season year.
 
#16 ·
Basically we'll be concentrating on the following areas

1. Larger aluminum radiator (more cores and larger side tanks), we can go a bit thicker on the radiator with an electric fan.

2. Increasing the capacity of the cooling system with a larger header tank or tanks (without touching the heater system), Taffy has a sample header tank made out of aluminum (standard size) and I'll post a photo once I find it. I'd like to go with a bigger version of that tank but incorporate a visual level indicator window.

3. Oil cooler system overhaul / clean and maybe another oil cooler in series

4. Most of the heat soak happens when stuck in traffic at idle, the S38 seems to generate an enormous amount of heat even at idle so good airflow from the fans at idle and low speed.

5. I like the idea of the non water based coolant

I experimented with removing the rubber bonnet seal strip near the windscreen to let the heat out (E34 M60 530i) but it makes no measurable difference.
 
#18 · (Edited)
4. Most of the heat soak happens when stuck in traffic at idle, the S38 seems to generate an enormous amount of heat even at idle so good airflow from the fans at idle and low speed.
My car is originally from South Africa, and, is a hot climate version.

The problem you describe above plagued me ever since I replaced the fan clutch.

On the original (fitted during manufacture) fan clutch, the oil used to get upto 100 deg on motorways under heavy driving, and water temp would be straight up in traffic (slightly before straght up on motorways).

After the new fan clutch was fitted, the oil temp would always climb in standing traffic, and, once it got hot, (over 90 degs) it never cooled down again until switch off, or driven at steady 100 - 120 kph for 30 minutes in top gear (low load, lot's if incoming air).

My engine fan never sounded the same with the new fan clutch, much much less noise (slow speed before you could hear the fan above the engine, for example driving round town).

The fan clutch was tested, was OK. it was swap'ed out, no change. I have chased this fault for over two years in different ways, but, in the end, the "in traffic" temp problems have been resolved by changing the oil thermostat located at the bottom of the oil filter housing (large metal canister). We also (at the same time) removed the oil cooler and fully cleaned it out (it only contained old oil, it was not sludged up).

I really am totally amazed at the difference since then.

I now see 78 deg C on motorways, always! even at 200 kph!

I rarely see more than 80 deg C in traffic (it was 105 - 110 before), and, even under very hard track use, only see 95, and that drops on long straights down to 90....


hope that helps!
 
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#20 · (Edited)
Quote:
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0> <TBODY> <TR> <TD class=alt2 style="BORDER-TOP: 1px inset; BORDER-RIGHT: 1px inset; BORDER-BOTTOM: 1px inset; BORDER-LEFT: 1px inset">Originally Posted by 1day

I now see 78 deg C on motorways, always! even at 200 kph!

I rarely see more than 80 deg C in traffic (it was 105 - 110 before), and, even under very hard track use, only see 95, and that drops on long straights down to 90....


</TD></TR></TBODY></TABLE>
That is oil temp?<!-- google_ad_section_end -->

YES OIL TEMP in deg C


added a photo taken on the way back from a track day
 

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#22 ·
No way, that is high pressure area. That´s why cabin air intake is there and you remember old USA cars with cowl induction hoods. Air is coming in, not out.
It isn't a high pressure area until the vehicle is moving , my idea was as a 'heat exhaust vent' to try and improve under bonnet air flow and remove heat pockets when the 530i was stuck in traffic.

It didn't have a noticeable effect.

This idea worked REALLY WELL on my old competition Willys Jeep , I saw a 15 deg C drop in water temp , it went from constantly wanting to overheat to being reliable. On the Jeep I had the vent holes on the side (you can see in the photo) and another 8 x 50mm dia holes on the top of the bonnet
 

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#24 · (Edited)
when stationary I think the design is that the engine fan blows air at the inside of the bonnet, which then forces the exchange of heat into the air (from the head / exhaust manifold areas), and then this now hot air is forced downwards (no where else to go) and out from the engine bay around the area of the transmission tunnel.

in reality this means that the hot air mainly exits from under the car via the side of the car, not the rear (as we are talking abut a stationary car).

I found that most of the hot air escapes around the the front edge of the front doors, I worked this out by standing next to my car with the engine running when hot using bear legs....

so, if you remove the engine fan, you need to replicate the above air movement - which I dont think you will do very well using a radiator mounted fan...
 
#26 ·
So the main problem is the outside temperature and thus lack of enough air or coolant flow.

Isn't your car equipped with A/C? Because then you already should have an electric fan (2 stages). These stages are triggered by coolant temp (right/exhaust side) in the radiator or A/C system. Adding this wouldn't be much of a problem my gues.

When looking in realoem / ETK at the viscous fan you will see an interesting thing. There are 3 (waterpump) pulleys available,
Stock : 144mm
Stock from 09/1989 : 130mm
Japan or from 11/1989 : 122mm
AUStralia : 102mm

The smaller the diameter, the more rotations it will make if other pulleys (>crank) are kept similar. SO when the car is stationary it will pump more coolant through the rediator to cool down by the viscous fan/electric fan. I personally would go for the smallest. I also think that enviromental temperatures are higher when looking 20-25 years back. This would be an great update for everyone expire coolant problems in countries were M5's were originally not imported or not delivered. There is of course a reason why BMW used different pulleys for different countries. An ECE car with 144mm would of course have problems in a climate like Australia.

Different radiators discriptions are listed but don't differ from part number although hot climate/australia is mentioned.

Also thermostat is not different. And I would only go lower than the stock 79°C for racing applications. Your car/engine should be running around 80°C without problems.

The coolant reservoir is in some M5's equipped with a steel? pipe. I was told that you could enter pressure here to build up pressure in the coolant system for a higher boiling point.


My advice, check the stock waterpump pulley, if its not the smallest make one your own (you must balance it) or order the smallest at the dealer. Also add the electric fan with dubble thermo switch. It should kick in at 91°C (stage 1) and 99°C (stage 2) or a seperate module with PWM control. There should be a plug in the (stock) radiator for the dubble thermo switch.

The downside of an (staged) electric fan is, it creates peak temperatures > it waits until a certain temperature exceeds (91/99°C) and then activates the fan, waits for it to exceed a lower temperature point to de-activate it. A viscous fan is more variable and doesn't create these peak to peak temperatures (less stress for the engine I suspect). Downside of it, it takes power from the engine all the time (why 316i/318i don't have them).
Nowadays you have PWM controlled fans which should replace the viscous fan due to emissions. Only the stock ECU of the M5 isn't able to control these.
 
#30 ·
there are also different water pumps. a 'normal' and a hot climate version. I put the hot climate version (and smaller wp pulley) in my sedan recently. From realoem.com:

01 RMFD WATER PUMP 1 11511315559 $336.50
For vehicles with
National version Auatralia
or
Hot-climate version
L810A=Yes

S823A=Yes
01 RMFD WATER PUMP 1 11511315563 $336.50
 
#47 · (Edited)
there are also different water pumps. a 'normal' and a hot climate version. I put the hot climate version (and smaller wp pulley) in my sedan recently. From realoem.com:

01 RMFD WATER PUMP 1 11511315559 $336.50
For vehicles with
National version Auatralia
or
Hot-climate version
L810A=Yes

S823A=Yes
01 RMFD WATER PUMP 1 11511315563 $336.50
The US M5 is OE with the 1-315-563 hot climate w/p and 102mm w/p drive pulley (41% overdrive above the OE 144mm drive pulley on the M88/S38B35 and option for E34, B36/B38 engines) and I anticipate that is the cause of many E34 upper radiator hose and radiator inlet tank failures. These parts deliver maximum coolant flow, circulation pressure and at redline the coolant pressure into the radiator is the highest of any E34, M5 variant.

I have a 112mm w/p fan drive pulley (10% under drive) and I will be upgrading the radiator to a 650mm wide (S38 OE is 610mm) version used on the E34-540 & E31-850CSi 5.6 liter V12, once I get all the upgrade details, mods, and parts (fan shroud, oil cooler, upper hose, air box mod, etc.) worked out.

FWIW, I figure any well maintained M5 driven on the US roads will never suffer form high cylinder head temps because there are no roads with unlimited speed limits, therefore the maximum coolant circulation delivered to the head by the hot climate w/p and 102mm drive pulley is not necessary, provides an excess in the cooling system design margin and just increases the risks of a coolant system failures due to excess pressures developed in the upper radiator hose and radiator inlet tank during the often spirited WOT redline runs through the gears, occasionally to 100MPH (Go Directly To Jail Speed) and that takes a hole 12-13 seconds!! Even in the high altitude, steep incline mountain roads the amount of time spent at or near WOT is very limited and not at all taxing on the M5 cooling system.
Just the opinion of a M5 owner with 24 years of spirited driving experience during the summer on the Western US high desert and mountain roads!
 
#31 · (Edited)
My M5 is a hot climate version and already has the small pulley

On my 1980 J20 Jeep pick up project I've gone even more extreme on under bonnet cooling airflow, I've installed an adjustable outflow vent from a Boeing 737 as well as a 6 core truck radiator. High temps were also a problem on the Jeep in the past , not in off road use but in Jakarta traffic.
 

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#36 · (Edited)
I can certainly get specs for you. BTW that price is very high, I'd be happy to help get it for you cheaper.

No its much larger and flows significantly more than the auxiliary fan, keep in mind newer cars have a single main electric fan which eliminates the need for the aux fan and the mechanical viscous fan but requires a more elegant control strategy.

Haha looks familiar, back when the car drove!

I finally got a chance to have a good look at the aluminium radiator that was made up , it's actually slightly smaller than the standard M5 radiator so there won't be much of a cooling performance improvement other than the material used but the aluminium necks are a huge improvement.

We'll see on the cooling once it's installed.

This is a prototype radiator which will be going into GA25331 (Taffy's white M5), it's external dimensions are identical to a standard M5 radiator and once it's in we can see where we can push the boundaries now we know the limitations of the local fabricator.

Standard M5 radiator

Cooling core area : 600mm x 438mm = 262,800 mm2

Cooling core volume : 600 x 438 x 40mm = 10,512,000 mm3

Weight : 5.419 kg (did you know the weight of the radiator is stamped on the base plate ?) I weighed it at 5.5 kg on my not so mechanical accurate scales.

Coolant capacity : 3 litres

Fabricated radiator



Cooling core area : 570mm x 445mm = 253,650 mm2

Cooling core volume : 570mm x 445mm x 35mm = 8,877,750 mm3

Weight : 4.5 kg

Coolant capacity : 3 litres (bigger volume in the radiator side tanks)

On paper the aluminium radiator looks like it will underperform compared to the standard radiator , it will be interesting to see if the different materials makes up the difference.

The main reason Taffy had this made up was to increase reliability on the radiator hose necks.

Fabricated expansion tank

The aluminium expansion tank is excellent , it's the same weight as the standard plastic expansion tank (1kg) and holds 2 litres (1 litre for the standard), the expansion tank and the radiator combined as a package should show an improvement.

The next batch we'll incorporate a coolant level window.

An additional litre of coolant will be useful and again we can go bigger.
Interesting work. As I'm sure you know make sure you have proper ducting to the radiator and from the fan and have at it. I agree that the aluminum is more robust but there is a slight weight penalty. Whats your reasoning behind the additional thermal capacity in adding coolant? Looking forward to updates!

-Greg
 
#35 · (Edited)
I finally got a chance to have a good look at the aluminium radiator that was made up , it's actually slightly smaller than the standard M5 radiator so there won't be much of a cooling performance improvement other than the material used but the aluminium necks are a huge improvement.

We'll see on the cooling once it's installed.

This is a prototype radiator which will be going into GA25331 (Taffy's white M5), it's external dimensions are identical to a standard M5 radiator and once it's in we can see where we can push the boundaries now we know the limitations of the local fabricator.

Standard M5 radiator

Cooling core area : 600mm x 438mm = 262,800 mm2

Cooling core volume : 600 x 438 x 40mm = 10,512,000 mm3

Weight : 5.419 kg (did you know the weight of the radiator is stamped on the base plate ?) I weighed it at 5.5 kg on my not so mechanical accurate scales.

Coolant capacity : 3 litres

Fabricated radiator



Cooling core area : 570mm x 445mm = 253,650 mm2

Cooling core volume : 570mm x 445mm x 35mm = 8,877,750 mm3

Weight : 4.5 kg

Coolant capacity : 3 litres (bigger volume in the radiator side tanks)

On paper the aluminium radiator looks like it will underperform compared to the standard radiator , it will be interesting to see if the different materials makes up the difference.

The main reason Taffy had this made up was to increase reliability on the radiator hose necks.

Fabricated expansion tank

The aluminium expansion tank is excellent , it's the same weight as the standard plastic expansion tank (1kg) and holds 2 litres (1 litre for the standard), the expansion tank and the radiator combined as a package should show an improvement.

The next batch we'll incorporate a coolant level window.

An additional litre of coolant will be useful and again we can go bigger.
 

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#37 ·
I live in Phoenix,AZ and the outside temps are around 110F. On the way home tonight my 'check coolant level' light came on and saw the temp gauge soar. Turned off the car and coasted into a parking lot...the top radiator hose popped right off.

I replaced the Radiator with an OEM and hoses in Feb 2014 (the water pump and thermostat was replaced in Oct 2013) and filled it up with Engine Ice. All has been in good working order. At traffic lights I hear the fans (car is all stock).

My 02 M5 was originally ported in New Jersey and other history in New Hampshire. I saw the information on this post about different parts based on the car location. But when the mechanic order the water pump/thermostat, would it be driven based on the VIN or where the car is located? It appears that the pressure increased enough to pop off the radiator hose, what would have built up the pressure so much? Coolant Temp? Water Pump went bad? Thermostat went bad? Or the car just can't handle the 110F temps with these stock parts?

The summer is just heating up here in Phoenix, what should I do 1st, then 2nd, etc...to keep this car cool during these hot months?

Thanks for your suggestions
 

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#39 · (Edited)
I live in Phoenix,AZ and the outside temps are around 110F. On the way home tonight my 'check coolant level' light came on and saw the temp gauge soar. Turned off the car and coasted into a parking lot...the top radiator hose popped right off.

I replaced the Radiator with an OEM and hoses in Feb 2014 (the water pump and thermostat was replaced in Oct 2013) and filled it up with Engine Ice. All has been in good working order. At traffic lights I hear the fans (car is all stock).

My 02 M5 was originally ported in New Jersey and other history in New Hampshire. I saw the information on this post about different parts based on the car location. But when the mechanic order the water pump/thermostat, would it be driven based on the VIN or where the car is located? It appears that the pressure increased enough to pop off the radiator hose, what would have built up the pressure so much? Coolant Temp? Water Pump went bad? Thermostat went bad? Or the car just can't handle the 110F temps with these stock parts?

The summer is just heating up here in Phoenix, what should I do 1st, then 2nd, etc...to keep this car cool during these hot months?

Thanks for your suggestions
Checked realoem, and can't find hot-climate waterpump,pulley, thermostat or radiator for E39 M5 ('02). When mulitply parts are available an "S" code apears. Like S199 is for a car without catalic converter equipped you have different ones if parts deviate from each other. By entering the VIN in a VIN Decoder (availabale on the web) you can see which "S" / options your car was delivered. When ordering parts you have to keep these codes in mind when ordering parts. I am not 100% sure if ETK is able to come up with the right parts when entering a VIN. I know for some cars it doesn't filter it.

Nowadays cars are tested in the most extreme conditions (Arizona, death valley to Alaska) to see if the vehicle handles under all conditions. Your car and E34 M5s should be able to drive without problems during these temperatures.

In both cases several things could be the cause:
- overfilled reservoir > check level is between spec when COLD > to much water creates to much pressure
- not right tightened hose clamps
- head gasket failure which created air in the system and thus overheats (on S38B36/38 the connection from exhaust side coolant pipe to reservoir tank is known to give overheating problems once clogged).
- If the system pressure is to high it should blow off pressure through the reservoir cap (1.4 or 2 bar) an not by popping of a hose.

I would do the following: ** during all points > keep an eye on the coolant level and keep it at the right level
- refill the system of your car
- set the heater to max temperature so air from the system could be extracted
- turn ignition on while filling the coolant (electric waterpump for climate control turns on and already starts to pump coolant once present and helps bleeding the system).
- open coolant bleeding screw(s) and wait for coolant to come out. Close bleed screws.
- once done start the engine and let it idle for a short while, open bleed screws to see if coolant/air passes.
- important, rev the engine fast to 4-5k rpm 3 times after each other. This way the coolant pump sucks water and air will be pumped away, open bleed screws again after this to check for air.
- check if there flows coolant water at the reservoir cap (when cap removed) there is a small hole on top of it which should pump out coolant in to the reservoir, especially when rev-ing the engine.
- Fill coolant to required level
- close the cap and drive to heat it up.
- let it cool down a while and check coolant level is between specification level.

Additionally I would check for HC in the coolant with a gas analyzer or head gasket tester after a strong run (high pressure created during the run and can blow air in the coolant system). A tiny leak can cause this while you don't experience coolant loss problems.

Hope this helps. I can check ETK (dealer version) later this day to check if different coolant parts exists for E39 M5.
 
#38 ·
The top radiator hose coming off in high temp / high humidity environments seems to be a problem with the standard components. Usually its the top hose to the radiator but GA25324 blew it off the water pump.

This could be something new as the M5s age.

I wasn't so lucky , I have a warped head on my M5 , no soaring coolant temp , no low coolant warning until after the engine was shut down.
 
#46 · (Edited)
Nothing new!!
This may be a repeat post/reply and it is worth mentioning again.
The problem with the upper radiator hose popping off is: new coolant hoses are often replaced without installing new hose clamps!!

If you disbelieve the concern at least test your hose clamps for binding through the point where they will be tightened before you re-install them.
The point of original use can often be spotted by the deformation in the band where it was previously tightened.

That I have observed, the problem with the upper radiator hose popping off is: new coolant hoses are replaced without installing new hose clamps!! FWIW, the upper hose is the highest pressure point in the cooling system because the coolant pump is forcing the coolant through the radiator & cooling system and the pressure at the upper hose increases with engine RPMs...

Yes, the hose clamp worm drive very often binds (not can!! but very often!! like 1 out of 2) when they are re-tightened on a new hose.
The worm drive gets sand, other foreign material in the worm drive mechanism over time and/or the clamp worm drive becomes deformed (worn spot from tension on the band) that prevent it from freely re-tightening on the hose connection.
Even if you attempt to clean out the worm drive and add a lube it is still susceptible to binding and the sense/feel that the hose clamp is adequately tightened and making a tight connection on the hose bibb is just a false indication.

So do yourself a favor and replace every hose clamp at the hose ends with all the new hoses. Not that expensive compared to the expense of a blown hose connection even if you don't damage the engine. New clamps are less expensive than a single gallon of coolant!!
I use the L35-52, Hose Clamp, p/n: 11 53 1 708 296 as replacement clamps on the upper and lower hoses and other location that require this size clamp. They are a little more expensive at $3.25 each ($4.00 BMW Retail List) and they are a better design than the original large hose clamps on the M5.

It is the little things that often create the biggest problems and the little things are easy to eliminate!!
Again, if you dispute my observation just try running the used clamp thru the range it will be used, it will make a believer out of you!!

Yes, I stock & restock my DIY parts bins with the range of hose clamp sizes (worm drive and crimp style), so when I do the hoses (I do PM on 3 BMW's) I have the correct clamps available and I'm not tempted to reuse the old clamps!!
 
#41 ·
I'm in the middle of work projects at the moment (about to head off for a salvage project in Papua New Guinea) and the M5 is still sitting there waiting for more accurate measuring equipment so we can order everything we need

I'm thinking of a new radiator, larger header tank and an aftermarket fan about 2,500 to 2,800 cfm from jegs.com

We'll update once we get moving again.
 
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