86.5 Auxiliary Fan Clutch
11-12-2018, 10:27 AM
#1
Intermediate
Thread Starter
86.5 Auxiliary Fan Clutch
Looks like the fan clutch on the auxiliary fan isn't working properly. Car is heating up when sitting at a light and the fan doesn't kick in. Relay is fine and the sensor is okay. I have seen a thread where folks have swapped out the OEM fan with a VW or other manufacturer. Anyone there have a suggestion or thread on a replacement? Thanks in advance.
11-12-2018, 10:54 AM
#2
Rennlist Member
I am confused. You have a belt driven fan with a clutch that sucks air through the radiator and an electric pusher fan in front of the radiator that forces air through the radiator and condenser. The belt driven fan has a clutch that relies on a silicone fluid to operate. This fluid often leaks out and causes the fan to neglect its job. The pusher fan is electric. It has no clutch.
There are numerous threads on repairing/refilling the belt driven fan clutch with fluid from a Toyota dealer or a silicone fluid used in the drivelines of radio control model cars. There are also options for replacing the belt driven fan with an electric fan. These range in price and sophistication from fans taken out of mid-90's Ford's to the lovely fan setups made by Hans.
As for the pusher fan, my knowledge is limited. Mine goes on when I turn on the AC, so I conclude, perhaps wrongly, that all is well.
I wouldn't want anybody in a car with an aluminum block and heads to be casual about overheating, but your 32 year old temperature gauge may not be the semi-precision instrument it once was. I have an infrared and other thermometers to check various temperatures. My 86.5 is low miles and in very good shape, but I view all the gauge values as rough estimates. You may not have a cooling problem at all.
Anyway, your choice of an 86.5 shows you are a person of refinement with a highly developed intellect. You are in the right place on the internet to get advice about your 928. The depth of knowledge here is simply awesome and Search is your friend.
There are numerous threads on repairing/refilling the belt driven fan clutch with fluid from a Toyota dealer or a silicone fluid used in the drivelines of radio control model cars. There are also options for replacing the belt driven fan with an electric fan. These range in price and sophistication from fans taken out of mid-90's Ford's to the lovely fan setups made by Hans.
As for the pusher fan, my knowledge is limited. Mine goes on when I turn on the AC, so I conclude, perhaps wrongly, that all is well.
I wouldn't want anybody in a car with an aluminum block and heads to be casual about overheating, but your 32 year old temperature gauge may not be the semi-precision instrument it once was. I have an infrared and other thermometers to check various temperatures. My 86.5 is low miles and in very good shape, but I view all the gauge values as rough estimates. You may not have a cooling problem at all.
Anyway, your choice of an 86.5 shows you are a person of refinement with a highly developed intellect. You are in the right place on the internet to get advice about your 928. The depth of knowledge here is simply awesome and Search is your friend.
11-12-2018, 11:18 AM
#3
Rennlist Member
Otto is correct, the aux fan is simply an electric fan, I THINK single speed? I think there is a hot condition where it can come on with the car off, so maybe that has a lower speed, but there is no clutch on this fan. You say you have verified relay and sensor...so when you unplug the radiator coolant sensor and connect the wires with the car running, the fan does not come on? Assuming it is indeed getting +12V that would suggest to me that you have a bad fan motor (but definitely verify the presence of +12 and Ground at the fan motor).
Btw, it shouldn't come on every time you turn the AC on, unless it has been "customized" to do so. Stock, it won't unless the temp switch in the radiator is triggered or the high pressure switch in the AC (other than the intake temp switch which can supposedly turn it on with the car off).
Btw, it shouldn't come on every time you turn the AC on, unless it has been "customized" to do so. Stock, it won't unless the temp switch in the radiator is triggered or the high pressure switch in the AC (other than the intake temp switch which can supposedly turn it on with the car off).
11-12-2018, 11:27 AM
#4
Rennlist Member
I will add that if you're heating up at stop lights, regardless of the state of your aux fan you probably need a new fan clutch on the belt-driven fan. Roger has a much cheaper replacement than the Porsche one....I have one, haven't installed it yet though.
11-20-2018, 10:23 AM
#5
Roger; this correct? You have a belt driven fan clutch replacement? How much $$ at this time?
and Eplebnista is correct: if your temp is seriously going up at idle, get an affordable HF temp reading gun and read the temp at the thermostat outlet and find out your actual temp status
and Eplebnista is correct: if your temp is seriously going up at idle, get an affordable HF temp reading gun and read the temp at the thermostat outlet and find out your actual temp status
11-20-2018, 01:30 PM
#6
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Replacement Fan Clutch $195
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
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11-23-2018, 11:30 PM
#8
Rennlist Member
The Aux fan normally comes on through a switch mounted on the AC dryer line. When the freon temp hits a certain level the fan comes on drawing power from a 30a fuse through a relay. There is also a switch in the water circuit that will turn the front fan on if the water temp gets too hot, I'm guessing this is a last ditch cooling system in the event the fan belt snaps. Note that on my car this fuse socket was warped because the pins needed a good cleaning. Now that they have it, the fan works fine.
The second way it can come on is through a temp sensor mounted up on the manifold front. This is fed by a second fuse that runs through a resistor to run the fan more slowly when the under bonnet temp is really hot. This will come on with the engine off, and is a good source of +12 for a relay to amplify the climate control relay to the compressor clutch (that relay in the climate control module is way too small).
It would be a good idea to make sure the front fan works. You can test it by jumpering the two wires coming from the dryer top. With ignition on the fan should come on, if it doesn't you have another problem.
The second way it can come on is through a temp sensor mounted up on the manifold front. This is fed by a second fuse that runs through a resistor to run the fan more slowly when the under bonnet temp is really hot. This will come on with the engine off, and is a good source of +12 for a relay to amplify the climate control relay to the compressor clutch (that relay in the climate control module is way too small).
It would be a good idea to make sure the front fan works. You can test it by jumpering the two wires coming from the dryer top. With ignition on the fan should come on, if it doesn't you have another problem.
11-23-2018, 11:34 PM
#9
Rennlist Member
Oh there's also one more switch: A temperature sensor switch in the torque converter ATF circuit. If that goes too high, the fan will come on as well. Learn something new every day....
11-24-2018, 12:35 PM
#10
Intermediate
Thread Starter
Thank you for the comments and suggestions. The culprit was the fan clutch. It was spinning but you could stop it with a folded newspaper. Replaced and now running correctly. Just wanted to close the thread.
11-24-2018, 08:52 PM
#11
Team Owner
Cool Runnins Bro............ have a great holiday season,
Thanks for reporting back.
FWIW I got a new fan clutch installed on that 85 I was working on,
and its plug and play,
the fan churns the air and the engine runs cool just like its supposed too
Thanks for reporting back.
FWIW I got a new fan clutch installed on that 85 I was working on,
and its plug and play,
the fan churns the air and the engine runs cool just like its supposed too
