aux fan stopped - solved

[shogun]

Sunday I had a problem that the aux fan stopped completely on my E32 750iL. Temperature here was 38 degree C, had wife and son with his wife and 8 month old baby in the car, on the highway traffic jam and the needle went up to 3/4, but not higher as I have a good working visco clutch, but aircon got warmer, probably due to icing as as the aux fan was not cooling. Made it home, when no traffic jam temp needle almost was in normal position.
Today I continued to check based on the info from Gale's site and the ETM. Replaced all related fuses just to make sure all are o.k., changed low and high speed relay, jumpered the plug on right side radiator, no change. Then I removed the bumper and the kidney grill, unplugged the plug on the aux fan and connected a spare aux fan, that worked, but with loud noise. Because the magnets inside aux fan motor are lose as often happens. Will repair that one next weekend with wrenching buddy Hairywithit and re-glue the magnets, so I have a spare aux fan. Disconnected aux fan again, measured with multimeter, all o.k., installed aux (about 8 years old) fan spins easy, so no problem with magnets.

Then I sprayed contact spray into plug of aux fan on aux fan and the connecting plug, O.K., fan runs on low and high speed again. Just oxidation of the pin contacts. The plug is just behind the kidney grill and rain will come there. I forgot, maybe better I additionally use some good tape to seal the complete plug portion from rain. So just another case of bad contacts/oxidization which caused a problem.
2 years ago I found oxidation on the spades of the high speed relay, also causing malfunction of the aux fan.

How to test:
http://www.nmia.com/~dgnrg/page_2.htm
http://www.bmw4life.com/repairs.htm

[632 Regal]

I am thinking of changing the switch to the lower temperature E36 one 61318361787. In city traffic my aux fan never comes on unless the AC is on, just doesn't get hot enough to trip the switch. This is good but the clutch fan runs hard all the time school bus style (in the city) and kills mileage down to 8mpg. My sons E36 doesn't even have a clutch fan and the cooler switch does it all. This switch is 80/88C vs the E34 91/99C 61311378073. Seems like a big jump but I don't see that it could cause any harm. I wont try this until I get another fan, mine sounds a bit worn and I don't trust it.

[shogun]

Some years ago I bought 6 of these 80/88 switch for my buddies here in Japan as in summer it is quite hot here. Looks like this http://www.ecstuning.com/ES2187553/
Especially the Alpina B12 B11 E32 guys wanted to have them. No problem at all to install it. But of course the engine bay will be a bit more noisy because the fan kicks in earlier.
On the other hand I would not try it without the good old visco fan clutch, that saved me this time again, otherwise with non working aux fan I and II stage the engine would have overheated.

Another option and maybe less risky without visco: one of my buddies has a E34 M5 for mostly driving on race courses for fun, but also registered for legal use on streets. He installed from a Subaru from a scrap car a dual electric fan, both with separate switches on the center console. So he only switches them on when needed, of course the temp needle has to be watched all time. The 2nd electric fan is rarely in use.

As for contacts, BMW recommends Stabilant22A, there is a TI:

Stabilant 22A Electrical Contact Enhancer Model: All BMW

Complaint:
Connectors which carry low current are more likely to form deposits which affect the resistance of the circuit through the plug connector. Depending upon the particular circuit these deposits can cause malfunctions and consequently activate warning lamps and check control indicators.

Remedy:
Part replacement can temporarily stop the problem.
If the connector is the problem then without disconnecting the connector measure the resistance of the circuit running through the connector to make sure the connector has a high resistance. A good resistor will have close to 0 ohms resistance.
Visually examine the male and female terminals in the connector housing by removing them. Look at the integrity of the wire crimps, and in some male terminals the integrity of the weld of the male pin to the terminal. Then reinstall.
With a zero residue electrical contact cleaner liberally spray the male and female connectors, and allow the air to dry.
Apply Stabilant 22A to both male and female terminals so they are saturated, and reconnect the connectors while they are still wet. When the Stabilant 22A dries it will leave a thin coating of polymer film which is conductive between mating surfaces, and is non-conductive between adjacent pins. It can also prevent the formation of more harmful deposits.

BMW has this available in spray bottles, also available from Wurth etc.

[shogun]

Today we solved the next aux fan problem. The owner of a 1988 E32 750 Alpina B12 visited me to fix the aux fan problem. Tested everything as described above, in this case the spades/contacts of the low speed relay were not having contact due to oxidation. Used my contact spray on the relay and the relay socket, installed it, worked on low. To test the hi speed fan and the temperature switch on the radiator under 'realistic' conditions, I then removed the visco fan clutch and let the engine run in idle with aircon on with aux fan running in low and watched the temp gauge, it switched nicely to hi speed aux fan speed when it should. So all works as it should again, just with the little help of good electronic contact spray.

[632 Regal]

I just realized my kids 96 e36 328i has no clutch fan, I thought it was by design but realoem says it has one. It is only using the front aux cooling fan. So far there have been no issues but this might be problematic. I would not try this with my 530 even if I changed the temperature switch to the E36 one. The way the clutch fan works so hard there is no way that little aux fan would do the job, especially if I ran the AC.

That Volvo fan retrofit looks to be a great solution for the E34, just need the fan, shroud, 2 way switch and the E36 temp switch to work right. Of course you need the right year and model which there are a bunch of. The E34 (at least my 530) thermostat is higher than the low speed sensor for the E36. Which raises my question...

Do the BMW thermostats temperature rating indicate fully open temperature? The Detroit metal cars thermostats indicate the opening temp. I remember this was discussed years ago but forgot the answer.

[shogun]

Do the BMW thermostats temperature rating indicate fully open temperature? The Detroit metal cars thermostats indicate the opening temp. I remember this was discussed years ago but forgot the answer.

I assume the ones on the older cars like E34, E32, E36 do not indicate fully open, it is just the switch on the side of the radiator which measures the coolant temperature and gives a signal to the hi or low relays, on the newer cars like for example
E39 there is an electric connection at the thermostat housing. That probably does the job.

the myth about the cluster engine coolant indicator

I have explained that before: There were in the past a lot of discussions what is right or wrong when the temperature gauge on the cluster temp indicator is right or left of the 12 o' clock mark.
The fact is:
Temperature indication on the BMW is not linear, they call it 'tableau', basically the indicatior at 12 o'clock can mean everything between roughly 75-110 degree Celsius. Everything in between 75-110 is just 12 o'clock. Plus/ minus 1-2 mm to the right or left (deviation cased by the parts installed).

The analog signal ist processed in the instrument cluster and compared with data in the coding plug. A corresponding signal is sent to the instrument. Five temperature support values are stored in the coding plug.
Exceeding the temperature limit stored in the coding plug will additionally send corresponding warning information to the check control and display it there.

That is written and shown here on page 4 of the instrument cluster check control training reference book http://www.e38.org/e32/BMW_pdfs/INST_info.pdf
What is NOT shown in the English version I found in the German version, here a copy of that page showing the temperature diagram curve in picture 14, and there you see the socalled 'tableau' between 75-110 degree Celsius.
http://s71.photobucket.com/user/shogun_bucket/media/cluster%20and%20OBC%20IV/20.jpg.html?sort=4&o=18

[bennyg]

75-110? I didn't think it was as wide a range as that. I remember finding something on the E34 540i that suggested the 1/4 and 3/4 marks were + or - 10C with about half that range confined to 1/2 or a couple ticks either side (that's the non linear bit). Which fits the 91/99C thermostat I believe the car has and what I have observed, but I defer in all things to pros.


Anyway I have a E34 540i with a clutch fan delete. It can handle the dry Aussie summer 40C+ days sitting still with air con on 1 or 2 for 10 mins, just. Aux fan kicks in just before the gauge reaches 3/4 and returns temp to 1/2 way in less than half a minute, as does going over 30kph.

If you don't spend too much time idling, and the cooling system and air con is top notch as they are in mine, it can work well.

I reckon I can feel the freed up power in the upper rev ranges too vs my other 540i (which has a 98ron chip tune and is def better sub 3000rpm)

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[shogun]

Sounds like a wide range, but on the gauge 75 - 110 degree C is just 2mm before 12 o' clock and the 3/4 mark
8386

and here for the Fahrenheit fans, 182 - 229 F
8387

I once tested 3 different clusters within 5 minutes on my E32 750, just to see the differences in the gauge at actually same operating temperatures (tested with a laser gun thermometer at the same point of the radiator), car was at operating temp and idling, a grey back, a white back and a blue back cluster.
Temp gauge difference 2-3mm before 12 o' clock up to 2-3mm after. So it even depends on the accuracy of the cluster gauge installed.

[632 Regal]

Anyway I have a E34 540i with a clutch fan delete. It can handle the dry Aussie summer 40C+ days sitting still with air con on 1 or 2 for 10 mins, just. Aux fan kicks in just before the gauge reaches 3/4 and returns temp to 1/2 way in less than half a minute, as does going over 30kph.

If you don't spend too much time idling, and the cooling system and air con is top notch as they are in mine, it can work well.

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Are you running the volvo fan conversion? My clutch fan kills mileage and performance. You can change the aux fan switch in the radiator with one from a E36 which will kick on a few degrees cooler.

[genphreak]

Great thread!

Kinda reminds me of the low pressure cooling system thread (http://forum.e46fanatics.com/showthread.php?t=948548) over an e46fanatics... lol

I like the idea of a lower temp switch and a fan system that is more efficient than the trusty visco+2 speed thermofan BMW favour, but if I go changing mine it will have to be a super-reliable setup with redundancy- the idea that either fan will get you out of trouble is a good one- down here in Oz the summer heat does not suffer fools lightly...

[bennyg]

Yeah I spoke too soon, it blew the high speed fuse last week on a 37C day. Maybe it was heat soak on starting up after 10min off because it's been fine since I put a new fuse 1min later. Touch wood.

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