[wildcat]

The rain we got here in So. Cal brought with it a lot of moisture and condensation and after alternating days of sun and rain, I started getting a crunching sound in the passenger side fan. I thought it was the bearings and dreaded the thought of finding a replacement.  I looked around and as it turns out used ones aren't that difficult to obtain and new ones are still available.  So o.k. lets' tear it apart and see what's  up. I discovered its not all that difficult to pull the whole assembly out. Remove the air-box and the large radiator hole on the driver side, disconnect the switch wire below it, that and the six bolts that hold the  fan shroud, the two plugs that power the fans, a couple of retaining clips that hold the wires in place and out it comes.

 

Of course after 140k plus they look really grungy. There are 3 deep socket lock nuts that hold the motors in place.  I unscrew them and out the motors come. The fans are held on by retaining clips.  A screw driver pry's them off the motors axle. If you're careful you can reuse them, they're pretty robust.

 

And what is revealed... unbelievable amounts of soot.  The armature is just covered with the stuff and if you shake the motor it comes out like a fine black powder, and in amounts that make you wonder that the motors ran at all.

 

The crunching sound was loud and the motor wirred, I thought its "catastrophe". And after seeing all that powder I'm truly amazed.  I get a can of carb cleaner and spray into the armature from the front and there's a whole at the six o'clock position and spray it there. More black powder... now mixed with the solvent, the sink is black with it. After I cleaned it as thoroughly as is possible, I rotate the axle of the motor. No crunchy sound. I compare it with the other motor which is also saturated with the powder, but it did not exhibit the same auditory phenomena.  They both sound and feel similar, so I clean out the second motor as well and figure that if the first motor doesn't work properly nothing lost but a little time.

 

I reinstall the fans... and voila! Both are running smooth as silk.  I finished that a couple of days ago and both motors are operating properly.  

 

I noticed about 6 months ago that the motors would resonate together for a time and then go out of sync.  That presumably means that they are running at the same speed which creates a harmonic resonance. That fluctuation has gone which is the best indication I have that they are working properly. Worth looking into if you've got the time to spare, could extend the life of those precious fans.  

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[MCL968]

Good info! I pulled mine when I replaced the radiator a while back, but I thought it better to leave well enough alone. I did clean the blades and I was surprised at how much crud there was on them, and also how much quieter they were after cleaning. Maybe before summer hits I will give cleaning the motors a shot.

 

Did you lube the bearings or are they even accessible?

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[Grandpa#3]

Good going wildcat , It is surprising what a little time and DIY can produce AND save a wad of money. That carb cleaner might have washed out some of the bearing lube so keep an ear out for any squealing.

Cheers,
Larry

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[Waylander]

I have repaired a couple of these fans with new brushes for the motors, they sure do fill up with crap,

 

the bearings are the phosphor bronze type that self lubricate, I just left them in a puddle of oil for a while to soak up the golden goodness,

 

I have also found that if they are a bit stiff or noisy the load required to start them fries the rad fan temp switch, it welds the contacts inside them together.

 

new fan switch time.

 

So if you get the chance clean them out and lube them up, might save you some pain later on

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[MCL968]

Waylander, where does one get these brushes?

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[Waylander]

I bought a selection of them off eBay and filed some down that were close in size.


Had cut and solder the copper leads but it was not too hard.


I do exactly the same with manual starter motors, I can buy the brushes loose and solder them in, I also buy the bendix drives and bearings for the starter motors and rebuild them, I have done seven so far makes a huge difference to the cranking speed


I like doing these sort of things for others, rebuilding calipers and so on, I just charge for the parts and post

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[Bulti]

I tried to open a fan motor once, but couldn't figure out how. At least not without being sure not to ruin it.

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[wildcat]

I thought about opening it up, but its got two rolled pins, and the casings have bent tabs.  They're really pressed on.  I saw a DIY on the 944 and the motor is not the same, not on the basic model. So I didn't.  The carb cleaner I used evaporates and I don't think it gets into the bearings.  They have to be sealed bearings or all that crud would have destroyed them long ago. I haven't had any squealing and the engine is running slightly cooler.  The temp gauge was typically straddling over the upper portion of the line, now its the lower portion, so I'm confident that they're running properly.  They're really quite sturdy. I may need new brushes at some point, so having done this, I'll take the next step when needed.  Thanks all. 

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[wildcat]

I was considering what I had learned in the process and concluded a follow up was in order.  Many parts can be rebuilt like alternators and such but this particular item, the fan motors, are not offered as "rebuilt". Having inspected them I concluded that they are difficult to take a part.  They have two rolled steel pins that project into the casing.  The casing is press fit with little tabs that could easily break off if pried back.  There is a spring of some sort inside the motor which balances the load of the armature. I checked those by pulling the armature out and the tension was good.  The point of this is that if the brushes or bearings go bad I would replace the motors. I have fixed some motors for other projects but not all are easily rebuilt.  Somewhere one needs to consider how far into something one is willing to go, due to time, cost, effort required. In this case with motors available, I'm inclined to replace them rather than try a rebuild. That is what I would have liked to know before I pulled those motors out. As it turns out I was able to fix them with minimal effort and discovered that they are heavy duty and well built to begin with. Unlike the 944 motors which I saw posted they do not lend themselves easily to disassemble.  Philosophically, after 140k some people would just go ahead and replace them with new ones. Its of a hobby of sorts with me so I took them out, cleaned them up and as they are quite rugged, it worked.   

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[az968]

I'm going to follow your cleaning up process this spring, just to be on the safe side before heading up to S.Lake Tahoe for the gathering. No noise right now, and only 80k miles, but 23 year old motors........

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[wildcat]

I had to replace the alternator awhile back.  I replaced the alternator alright, so I thought but as it turned out the cross member bar that is used to adjust the tension needs to be loosened first and then re-tightened. Unknown to me at the time, I sheered the bolt.  But you couldn't tell as the head of the bolt was showing. And what an ordeal it was as I had to tap the bolt and there's not much room for a drill. Had I known it was relatively easy to remove the fans it would have given me more room. Course now that I know about that little "gotcha" its not an issue. But when it comes to replacing the hoses, I would prefer to remove the fans to accomplish that.

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[MLB]

Hi Wildcat, I had noticed that my fans did not seem to spin very freely, stopping after less than a full rev, when given a flick by one of the blades, so after reading this thread I thought maybe they were getting gunked up as well. When I took the fan shroud out to inspect the motors, despite being a little crusty on the outside, the insides looked clean and not caked with black gunk like you seemed to find. Even the windings are still shiny. Did yours look a lot different from this?

 

   

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[wildcat]

The outer casings were kinda oily but for the most part they looked a lot better after cleaning.  Those part number labels are chromed like mylar and mine looked new after cleaning. The inside was caked with black powder and I wonder about the origin. I didn't think to take pictures as there was an immediacy about the situation. On inspection I suspected the grime was not from inside the motor and surmised it had been sucked in over many miles. Which is why I was endorsing an inspection. It would appear however, that while this was the case for my motors it may not be the case for all motors. I think its worth checking, especially if you hear any fluctuation in the resonance of the motors as I mentioned. That harmonic resonance is gone now.

 

As the picture illustrates, there are little tabs and no nut to hold the axle of the armature in place. The bearing assembly is riveted which means that the face plate will come out with the armature.  If you look on the back side of the motor from what is shown in the picture you will see two little holes with a "c" pin in each hole. This is a rolled steel pin that is holding something in place, a bearing or the brushes. It would have to be "tapped" out and replaced. The armature won't come out with those pins in there.  More than I want to tackle. 

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[MLB]

Hey wildcat, how do you disconnect that radiator switch? Does it pull straight out or does a twist first?

Thanks

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[MCL968]

Pulls straight out but it's tight because it has to be waterproof. Upgrade to the lower temp one to get better cooling, and torque it very carefully.
Pulls straight out but it's tight because it has to be waterproof. Upgrade to the lower temp one to get better cooling, and torque it very carefully.

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[wildcat]

What he said...  B)

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[wildcat]

Last night I did a midnight run... coffee and donuts and it was so nice out, we've got a high pressure trough over the county, I just decided to keep on driving and I don't remember whether I mentioned it but I disconnected the fan relay and installed a couple of switches instead... well sometimes I forget to turn them on, no big deal really I watch my gauges religiously, and anyway I'm cruising along and realize I haven't turned them on but the gauge is registering just below the line, about where it is when I have them on, except for when I'm pushing it, and I'm thinking isn't this cool (no pun intended)... here I am cruising along and I don't need the radiator fans running at all... for the FWIW dept. B)  

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[flash]

the fans only come on at specific temperatures (both low and high speed of each fan are set at a specific temp).  if it's cool enough outside, and you are moving at a decent clip, they won't come on at all.

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[Bulti]

92 and 102°C. In these temperatures (a little above freezing) they indeed do not come on. Only in very slow, stop-and-go traffic or when stopped. My gauge reads about 82°C, which is just about the lower white mark. My gauge is dead on when compared to the Durametric and I've just installed a new fan switch. Thermostat is standard too.

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[wildcat]

When I had the relay in they came on as soon as the car warmed up, sometimes a little before, but this isn't Belgium. Just thought it might be of general interest. 

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