Aux fan troubleshooting - Page 3

andrewwynn · #21 06-23-2018, 10:01 AM

Quote:

Originally Posted by audiophool;

PS: how many of you 3.0 guys know about the Beisan VANOS repair kit that puts the power back in these bricks? $60 worth of seals and 4 hours labour to make the VANOS work properly again. They say that the OE parts are only good for 20,000miles before they start to go.

Kit is amazing. (Including the press that crimps the vanos to tighten a worn seal)

After destroying one of the $20 Teflon seals I developed this method to push the new one in. Cut the old backing o-ring into 12-15 pieces at an angle and use the pieces to push the new Teflon seal into place.

I did the refurbish on an M62 so there were two vanos. The car had about 160-170,000 mi. the vanos were very sloppy the inner portion would turn from gravity. The repair made them like new only better materials so they say.

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andrewwynn · #22 06-23-2018, 10:07 AM

Also no matter how pressure built in the system the cap should have vented before the tank failed so either the cap or the tank must have been faulty.

audiophool · #23 06-23-2018, 12:37 PM

Quote:

Originally Posted by andrewwynn

Also no matter how pressure built in the system the cap should have vented before the tank failed so either the cap or the tank must have been faulty.

Agreed. It's a Behr cap and tank. The broken seam is so clean I can't believe it would have ever held. I'm planning to put a 1.2bar cap on when I'm done. Can't see how a cap would fail unless it was made with the wrong spring.

audiophool · #24 06-23-2018, 12:41 PM

Quote:

Originally Posted by wpoll

Exactly - it won't run. It is a three wire fan that has a heavy guage 12v input and a signal wire. The signal wire controls the fan in terms of turning on and off as well as controlling the speed. This signal comes from the DME/DDE and is a PWM signal - a square wave that varies in duty cycle. The signal is hard to duplicate without the proper test gear and a DC voltage on this signal wire does nothing.

The only practicle way to test it is to get the DME/DDE to turn it on. This can be done in INPA (activate menu) or as others have said, pull the AC pressure switch connector. Pulling the AC pressure switch creates a false condition that the DME\DDE reacts to by turning on the aux fan at full speed.

I've also heard and read (in BMW lierature) that the aux. fan does a start up test when the ignition is first turned on, spinning briefly at low speed then measuring the voltage generated by the free-wheeling fan. Seems legit but I can't say I've ever managed to catch it doing this - and I have checked. I check it with INPA at each service interval.

This. This is why I tried an output measurement on the fan +/-. Spinning the fan gave no reading.

andrewwynn · #25 06-23-2018, 12:45 PM

And It won't. The power feeds go through electronic control it's an open circuit until pwm is applied. It seems to be more complicated than a simple pull up/down transistor because when a signal is first applied you'll see a pulse of motion before you see it spin. I believe it's doing a self test which leads me to believe upon failure it should register an error.

audiophool · #26 06-23-2018, 12:49 PM

The stupid thing about the 'self test' is that it may set a code but it doesn't set CEL. With the fragility of these cooling systems, you'd think a problem with that fan would be cause for CEL.

wpoll · #27 06-23-2018, 04:03 PM

Quote:

Originally Posted by audiophool

The stupid thing about the 'self test' is that it may set a code but it doesn't set CEL. With the fragility of these cooling systems, you'd think a problem with that fan would be cause for CEL.

Isn't the CEL only used to indicated a fault that affects emissions, such as O2 sensors, mixture issues, CAT problems etc.? All othe faults are indicated either by OBC messages or by setting errors in the various modules, to be read via OBD.

audiophool · #28 06-23-2018, 04:31 PM

^^ probably, since CEL was a government mandated function...

Anyway, fan clutch out. All the dirt on the front shows its fluid came out and wasn't working. New one will be used.

Fifty150hs · #29 06-23-2018, 05:30 PM

"PS: how many of you 3.0 guys know about the Beisan VANOS repair kit that puts the power back in these bricks? $60 worth of seals and 4 hours labour to make the VANOS work properly again. They say that the OE parts are only good for 20,000miles before they start to go."

I did the VANOS seal replacement on mine. Noticed no difference in power or fuel mileage. It was worth doing, the seals were hard and probably not working very well and I needed to replace the valve cover gasket. I have an M54. Folks with the V8 that have done it said they didn't get anything out of the VANOS seal change either, BUT when they replaced the VANOS solenoids it made a huge difference. I haven't changed the solenoids on mine yet, so I can't say.

andrewwynn · #30 06-23-2018, 05:41 PM

CEL / MIL / SES will come on for myriad reasons that won't trip emissions but many of the codes are related to inefficient burn.

The fan (Electric especially) is non-essential in that the car will cool without it and will really only require it when the car is not moving and running the AC. The clutch fan will usually keep the car cool even when moving in slow traffic unless the ambient is very hot

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