Cracked Fan

[Funracer]

Was planning for months to take my 1995 993 Cab to Porsche Parade. A few day before departure I heard a ting sound at idle. Took our 996 to PP and today I found this:




I have owned the car for a couple of years. 86,000 miles. Have never loosened or adjusted any of the belts except the AC belt when I changed the engine mounts.

I am assuming this is the original fan. What are my options here? I believe the new ones are made of aluminum, which is fine with me. Will I need a new shroud as well? Alternator?

There is a very, very slight wiggle in the alternator shaft. When I push down on the shaft it does not seem to decrease the clearance between the fan and shroud. When I turn the alternator shaft independent of the fan I hear a knock sound at the same spot on every rotation.

Would this small alternator shaft movement cause this?

Thanks

[Funracer]

Checking prices. Fans seem to be fairly available.

Housing prices are all over the place. Superseded part numbers etc.

What is the difference between 964 106 667 OR and 964 196 667 IR? Is one for varioram? Automatic trans?

There are also 964 106 667 02 and 03.

Mine has 964 106 667 OR on it currently but the IR version is significantly cheaper. Not sure why.

[Herkyp]

I replaced my fan last summer after worn bearings caused contact. I rebuilt the alternator with new bearings and bought a new fan. I just sanded and repainted the housing. Good chance there is no need to replace your housing.

[Marine Blue]

Agreed on the housing, you shouldn’t need to replace it if it’s not deformed. Used fans are out there if you want magnesium, I know Autobahn in San Diego has a bunch and can pick out a nice one. It’s a little risky buying used since you don’t know history but if it’s in good shape it shouldn’t matter. Just keep it protected going forward so it doesn’t corrode.

[Funracer]

Originally Posted by Marine Blue

Agreed on the housing, you shouldn’t need to replace it if it’s not deformed. Used fans are out there if you want magnesium, I know Autobahn in San Diego has a bunch and can pick out a nice one. It’s a little risky buying used since you don’t know history but if it’s in good shape it shouldn’t matter. Just keep it protected going forward so it doesn’t corrode.

Hard to tell if its deformed. 1mm out of round would be enough to cause fan contact. Not sure how I would even measure that with hand tools. Maybe a string line.

Ive read aluminum is a bit heavier but less fragile than magnesium. So aluminum it is.

Luckily I have an alternator rebuild place near. Guys been doing it for 40+ years so he will get the alternator done.

I also have an SC. Had the fan and housing Cerakoted a couple of years ago and still really pleased with the look. Once I get the alternator back and the new fan I can reassemble and check for fan tip clearance with my original housing. Then off to the Cerakote shop.

Dodged a bullet in one respect. If we had taken this car to PP it would have ended badly.

I’ll update with pic later just because.

Thanks

[Cobalt]

just replace it with a new fan. It isn't worth messing with and can cost more in the end. The aluminum ones weigh 33% more so that is more mass moving at a high rate of speed which will wear out bearings and put strain on the belts and crank when speeds change quickly. Potential rob you of power. I have a 30 year old fan with 144k miles which remains perfect condition on my race car.

These fans should not just crack by themselves unless someone did something. Magnesium is quite strong and will last just as long as aluminum if made properly and the coating isn't damaged.

Are you sure the casting is broken or is it the coating? I have grit blasted fans that showed cracks like your second picture and it ended up just being the paint that was showing signs of cracking. Once removed the indication or crack disappeared and did not show up as a problem when penetrant inspected.

For some reason my photos which speak more than words.

[Funracer]

Look at the first picture. The blade is actually split up the middle. There is fan clearance high in the shroud but very little to no clearance between blades and shroud on the bottom. I think it has been rubbing for a few weeks and I did not know what was causing the “ting” sound. I could only hear it at idle while standing behind the car. Could not hear it while driving or even at idle while sitting inside the car.

New fan has already been purchased and shipped. I will update then.

Thanks

[Cobalt]

I missed that. Most likely the bearing went and that would throw the fan out of balance which created the contact point at the bottom and most likely the resulting damage to the fan.

I tell everyone they need to inspect the fans for paint and bearing issues constantly. New fan and bearing should get you up and running.

GL

Can you please post pictures of the old fan when removed?

[Funracer]

Originally Posted by Cobalt

I missed that. Most likely the bearing went and that would throw the fan out of balance which created the contact point at the bottom and most likely the resulting damage to the fan.

I tell everyone they need to inspect the fans for paint and bearing issues constantly. New fan and bearing should get you up and running.

GL

Can you please post pictures of the old fan when removed?

Here is one. I believe the date code is the pie in upper left. If so then maybe the dot shows Feb of 1995? This would be the original fan then on my 1995. It lasted 28 years and over 80K miles. Other than a very slight roughness in the green middle bearing there was no noticeable fan bearing degradation.



I installed the new fan and belts but even after reusing all the shims the new belts felt too tight. Ordered extra shims from PP and pulled the fan again so I was able to take some pictures of the markings. I made a mistake earlier the part number is the same ending in “2R”. Sorry its upside down.


The new fan looks like a production date of 2003?


Anyone know what the “LM” means? Aluminum maybe? Or Magnesium?



Did not replace the alternator or the fan surround. After loosening the belts the fan seemed to my eye to have more clearance at the lower end of the fan surround.

Also the new AC belt was so tight I ended up putting the old one back on.The AC belt is furthest out on the alternator shaft and so has the most leverage on it. The old one seems narrower and works perfectly so I will use it til I find a suitable alternative.

Put about 25 miles on the new fan and belts so far all good.

[Cobalt]

I suspect the LM is the Makers mark. All my casting had to have a Makers mark and our cage code for DoD work. Traceability to the manufacturer was important.

The fans can last longer but 28 years on any part is along time.

There should be a total of 6 shims. There are also different belt lengths you can try they reference several lengths in the PET.

[Funracer]

I have more than 6 shims currently. I think 5 large and 4 smaller. But I want my belts looser than spec to take pressure off the fan and alternator bearings. Somehow its all working at the moment.

[viejopatron]

What are the issues with these Fans and Bearings? At first glance, the bearing is undersized. I wonder whether excessive radial load (too much belt tension?) is the root cause.

Funracer, I like your approach of using more shims. Could you please give an update? I am interested in how it has performed over time.

[mepstein]

Magnesium is a very reactive metal. Look at magnesium engine cases, transmissions Mahle gas burner wheels, etc. mag cracks, crumbles and threads disintegrate. It’s good for what it does but doesn’t last forever. There’s a reason why Porsche switched back to aluminum for many parts.

[Cobalt]

Blame Porsche not the material. They didn't properly treat the parts and people don't properly maintain them.

Magnesium needs to be protected from the elements. Exposed surfaces to moisture, salts, and grime will eventually break it down over time. If properly protected will last as long as an aluminum counterpart. I manufactured Magnesium and aluminum parts for the DoD and many of my parts were still in service decades after we made them. Everyone thinks parts should last forever. The fact is take care of your car properly including checking the magnesium parts occasionally based on driving and storage conditions and they will last as long as the car. My 94 turbo wears its original fan and looks like new still to this day.

I have a fan with 144k track miles and when I last grit blasted it and painted it last year it was as good as new. The parts fail due to lack of maintenance and Porsche wasn't building cars to last but to perform. Also there are several types of magnesium alloys. All of which have their pros and cons and are effected by the elements differently. Porsche used what is called an aluminum based alloy which has about 9% aluminum in the alloy. This alloy requires a chemical conversion prior to paint to last. Porsche bypassed this step and used a paint to protect the fans and valve covers. This was a bad choice but no doubt the cost factor played a roll. The fans are still made of magnesium today and there is no better alloy for the job. The only option is some form of composite material. Carbon fiber or fiberglass would work maybe one day we can 3D print them but for now take care of the painted surface and you should be good for a long time.

Porsche switched back to aluminum valve covers due to cost. Magnesium can be made from the same tooling as aluminum. However the processing costs are higher than aluminum. I made some Chinook/Blackhawk/Seahawk/Super Stallion parts to name a few in both aluminum and magnesium and I charged nearly double for the mag part as the aluminum. I still run original mag valve covers on my 144k mile engine and so long as I keep it protected they are doing just fine. There are also better mag alloys with a higher purity and can withstand corrosion far better than the alloy used but this adds even more cost to the product.

144k miles on these mag valve covers and they are still working perfectly. Ironically the engine sheet tin was in far worse shape. But that car sits outside all the time under a cover.



This is my original 94 turbo fan and it has heald up perfectly but the car is a garage queen with only 38k miles.

[Funracer]

Getting frustrated with this car. Here I am, for the second year in a row, planning for months now to take the 993 to Porsche Parade. In Oklahoma City this year, a much longer drive from Florida than last years Parade in Birmingham.

Done a lot of work this year to make sure it will make the trip. This thread started with replacing the cooling fan and fan bearing last year after Porsche Parade. Then replaced every part in the AC system. AC now works perfectly. New clutch slave, supply line and master and rebuilt pedal cluster. No more clutch pedal hang. Replaced all four valve cover gaskets. Leaks greatly reduced. Porsche Parade in 3 weeks. I’m ready.

Except I’m not. A couple of days ago threw the alternator belt. Ordered the pulley update parts as mine still has the original small pulley halves. Paid $40 for next day shipping from PP so I can get this easy mod done before we go out of town Sunday for a week. Took the belts and pulleys off today and… spun the cooling fan and its contacting the shroud. Again.

Not happy. Alternator shaft is tight, new fan bearing super smooth. Checked and measured the shroud carefully and it is not warped. That leaves only the alternator as a culprit. Not sure how old this one is. Is there a date code on alternators? these are the only numbers on it I can find.



Turns out alternator new or reman 964 603 156 01 is out of stock everywhere unless one wants to buy the Porsche branded one for $1500. PP, Sierra Madre, AZHaus, RokAuto, *******,Sunset, Atlanta Auto etc all out of stock. eBay has a few shipped from Europe. Ended up finding a possible reman available on Pelican that has to be special ordered and wont be here til the 27th (2 weeks!) and only 6 days before we leave.

My plan now is to return the pulley update parts, wait for a reman alternator and do the Rothsport RS pulley single belt mod to eliminate 1 belt and the fan bearing. It irritates me to replace a perfectly functioning alternator because it “might” have an undetectable wobble just enough to cause my brand new $600 fan to drop 1mm and touch the shroud. Again.

[Cobalt]

Speculating here.

1 did you torque down the alternator properly? I have seen damage done to both housing and fan from a lose alternator.

2 Is the bearing you have now one of the new ones with the thin inner race? These are garbage compared to the original ones and have been know to fail if overtightened by the belt or not properly aligned. The fan housing is easily misaligned and I see independent shops make this mistake. Make sure everything is set and tightened down properly and it should last for years to come. I have also seen a number of remanufactured alternators be garbage out of the box so inspect it carefully before installing.

Best luck at parade. I am assuming you are going to spectate?

[Funracer]

1. Alternator was torqued into the beehive properly, and also torqued again a few months ago when I noticed the fan/shroud clearance at the bottom of the fan was less than at the top.

2. Not sure about the bearing having a thin race. Bought a new fan but cant remember if it came with the bearing installed or if I put it in. But no matter as the RS mod will eliminate this bearing anyway. If that doesn’t work I will get the Clewett setup but that install is more involved and I am getting short on time.

Yes we will be spectators. Signed up for Coral and a few tours.

Looking forward to it but I will take the 996 again if I don’t have confidence in the 993. We had to take the 996 last year and it blew AC duct foam all over the place for a week. It blew so much foam out there can’t be much left. Other than that it worked flawlessly.

[Funracer]

One thing I forgot to mention. When I spun the fan by hand clockwise, which is the way it goes when the car is running, no shroud contact. But when I spun it CCW the contact was immediate and bad enough to stop the fan dead in 2 turns. Not sure what this indicates if anything.

[Funracer]

Originally Posted by Cobalt

I have also seen a number of remanufactured alternators be garbage out of the box so inspect it carefully before installing.

Advised via email from PP today they have no reman alternators and no timeline for availability. They did have a new Aftermarket brand (Aftermarket is the name, never heard of it)
that was half the price of the Porsche brand. It will be here next week.

Will inspect accordingly.

[Funracer]

Not the original. Looks like June 2005 manufacture.