77tony

When the 94 is up to temp, the cooling fans kick on and sound like an F/A-18 Hornet launching off the flight deck. Is there a more modern fan design, that runs quieter and uses the same amount or even less juice? Possibly plug & play using the stock shroud ? TIA. 77Tony

SeanR

Are both the fans running or only one. When one has failed it does sound like a 747 warming up because the other fan is trying to make up for it.

Randy V

Are you saying the fans are variable speed?

I'm pretty sure they're on/off only, but I could be wrong.

And yes, the GTS fans are loud.

ALKada

I had the same exact problem until Sean diagnosed and found out only one fan was running. Get the car running and when the F-18 is ready for launch, pop the hood and with a flashlight check to see if both fans are spinning. I'll bet you a crab cake, beer and some of that gulf coast shrimp that it is not.

Rob Edwards

If you spin each fan by hand as hard as you can, is there any graunchy bearing noise? They are 17 years old and have however many miles it says on your odometer on them. I would imagine that those fans have seen a lot of duty if your '94 has been in Texas most of its life.

Here are audio files of 18 year old GTS fans, followed by brand new ones. The difference should be apparent if you listen with headphones.

Old:

https://webfiles.uci.edu/redwards/pu...%204-19-11.mp3

New:

https://webfiles.uci.edu/redwards/pu...%204-19-11.mp3

There's a great writeup on here about rebuilding fan motors, by 928Myles:

https://rennlist.com/forums/928-foru...iator-fan.html

77tony

Both fans do run when the car is up to temp. I also spun both fans with my finger and they are free wheeling when the car is off. Does not sounds like there is anything wrong with the bearings. T

dprantl

Yes, the '87+ dual electric fans have variable speed. If one fan is disconnected, the other fan will run at full speed. It's very easy to replicate this.

More than one of the popular 928 vendors sell aftermarket fans/fan shroud kits. The S-blade fan design is usually quieter/more efficient than the older standard blade style fans.

Dan
'91 928GT S/C 475hp/460lb.ft

DanielD

Is there an aftermarket fan set that runs using the stock fan amplifier? Plug and play so to speak...

borland

Based on my experience on my 90' S4, the fans run much quieter after rebuilding them with new bearings.

77tony

Car has only has 38,000 miles on it and spent most if it life in Virginia. Borland, It does not seem that the noise is coming from the bearings. It seems that this older fan design would not be as quiet or efficient as a new fan design? Some newer cars just seem to be much quieter to me when they are up to temperature at rest with the motor and fan(s) running. T

borland

Tony,

With worn fan bearings, the noise is actually due to the fans vibrating out of balance on the shaft. There is hardly any noise coming from the worn bearings. With new bearings, the fan balancing will be brought back into alignment.

The bearing grease deteriorates with age more so than with use, so I'd suggest you have yours rebuilt before going with any expensive alternative.

ashmason

Hmm, with sound its so subjective. My 90 GT was running only 1 fan and it was loud, it turned out to be a bad connection at the fuse box.

But here is the question, do the fans cycle speeds? Mine stay off while warming up, then both come on low when its getting warm (can't hear them), when things get toasty they ramp up again to mid speed. I can hear them but only just. They never get as loud or spin as fast as when I was only seeing one run.

Just wondering if your controller box is somehow going in to one fan mode and powering both at full speed?

Just my 2 cents. You could remove the fuse from one and compare.

Ashley

Alan

The GTS (and late S4) fans are 2 speed - not really variable. They should both run at the same speed at all times. both off, both half, both full. if one fails the other will run at full speed whenever the fans need to be on. The fans will always run when the AC is on, otherwise they will cycle and change speed depending on temps. I'd say mine are quite loud compared to ther cars...but there is a lot of heat to dissipate compared to many other cars too...

Alan

FredR

I use thr SPAL 12 inch dual fan set similar to that used in the kit 298 specialists use. To make the stock kit fit is messy and I had to fabricate mounts etc, My fans sounded like a dog until I replaced them. I have had them about 4 years now and no problems to date even in our high temps.

To make the setup look stock you have to butcher an original fand shroud & mount it on top. Once complete it is worth it but it is laborious. I presume replacement fan motors shoud they be necessary, will not be too expensive.

Regards

FredR

SQLGuy

I had to rebuild the fan motors in my GTS, but they were in particularly bad shape because they had been swapped in from an '88 S4... at least I'm assuming that the fans stayed with the shroud when this "custom" job was done.

Anyway, they got a lot quieter afterwards. If you search, you'll find the process. It's a bit tedious, but only about $35 in parts for the two fans (bearings, high grade grease for the bushing, electric motor cleaner)... it helps if you can spot weld the bearing covers back on, but rivets are an option as well.