robt964

Yes thats an interesting question. I'd personally favour a plastic one here over CF.
The 964 ones deteriorate due to the choice of material they're constructed from. Any nicks or chips and they'll corrode fast. What were the earlier ones you refer to made of?

cobalt

Turbo fans are not compatible unless you replace the entire housing and are from the 930's they have straight blades vs the curved blades. You are flirting with disaster by starting your engine. The fan is made of magnesium alloy and will corrode quickly if exposed to the elements. That is why it is imperative that everyone inspect and touch up any damage to the surface coating regularly. The factory painted them Zermatt silver but it turns to goldish color from heat and ozone. Better to look crappy than have it deteriorate and fail.

I agree with everyone it is a PITA job so plan on doing a complete rebuild on all parts as needed you won't want to go through this a second time.

Also belt tension is adjusted by a series of shims. You add or subtract as needed.

IIRC vertex makes an aluminum version however it is heavier by 33%.

LPMM

A lightweight and durable version as opposed to the Mg would be nice.

Thanks Anthony. After doing some digging and as mentioned earlier, I realized that Turbo fans are not compatible without also changing bunch of extras, thus adding to the cost. I have not started my engine in months and I don't plan to do so until I get a new fan. The car has been stored for the winter, so what's another month or so? After all, it was snowing a bit yesterday.

Thinking of giving it a quick paint spray before installing to make it easier to touch up later.

That's what I gathered and I'll just reuse whatever I will remove.

robt964

Anybody UK side have an old dead (but relatively intact) fan laying around?
I wonder if a company like Kenlow would be able to reproduce an equivelent from a suitable modern plastic? Doesn't hurt to ask the question, especially if the donor fan where suitable enough to cast a mould from....

HalV

Laurent, I bought a 10 mm triple square stubby tool (part #STSM10SE2) from the snap-on website when I changed my belts. It was about $10 including shipping.

I should have all the other tools needed to do this job as well. Let me know if you need some help. I probably wouldn't be able do it until early June. My current task on the weekends is preparing for my oldest son's HS grad party.

I'll likely be tackling my alternator pretty soon as well.

LPMM

Hi Hal,

I'll go to Napa down the road to see if they have it or else I'll order from Snap-On, thanks for the link. I appreciate the offer but I feel bad about having you drive over as I know you are busy. Same here, with my daughter's swim season starting up, it is tough to get some free time on the weekends.

Anyway, I am ordering the parts, got some good feedback from folks, found some threads, so I feel like I'm halfway to genius status right now. Now, I am sure that this will be a multiple weekend project and that my ego will quickly get deflated, but if you bring your car you can help me put the pieces back in mine and then we can do yours.

Name the weekend, I'll have beer and pizza ready.

gristle101

I just struggle to think of why Porsche would choose metal over plastic for these fans. I know they spin quickly, but it's only half the engine speed. I'd say the mean engine speed for a mostly road-going engine is 1800 rpm, and 3000 for a track going car. So that's a 1500 rpm lifetime average for the fan in a hard life. Is deterioration, flexion and potential shearing a risk under these conditions after a long period of use? Will ozone break down plastic?

Wow, I'm stoked, I want to look into this.

FeralComprehension

Are you certain? Going by memory the crank pulley is significantly larger than the fan pulley, so you'll get more than 1 fan rotation per crank rotation...

cobalt

Considering how far plastics have come since these were designed and made I guess if times where different they may have used plastic. The flat fans used on the race cars were usually fiberglass. Composites and other materials were very expensive and untested back in the 80's and 90's. Magnesium alloy was tried and true and was perfect for the job back then and even if you allowed it to get exposed to the elements it would have lasted the 10+ years max they intended these cars to be around. Porsche was in a very precarious financial state when these cars were built. I am sure testing new materials was not high on their list although they did switch from Magnesium alloy on the valve covers to aluminum and then plastic on the 993's which was an Achilles heal

Mr.Alex

If there was a nick or something, what would be the best thing to use and touch up the damage? I've heard Mg can be picky with whats used on it.

cobalt

Anything is better than nothing. The trick is to catch it early especially if the car sits outside or sees salty winter use. The factory color paint was zermatt silver. If you catch it before corrosion sets in you can keep it going for a fair amount of time. Ideally these should have a chemical conversion done. Dow treatment of some sort usually what they call a Chrome Pickle. This will etch the surface, remove corrosion and bond a protective coating to the surface, prior to painting again. Unfortunately that has its own concerns so most just paint. Proper cleaning of the area with some fine emery cloth and a dab of paint should suffice and just keep it protected as more chips occur. No matter what you do the edges will get chipped from sucking in debris from the engine compartment.

repguyMN

Hey Laurent and Hal,
Put me on the list for help with your projects. I am always interested in learning more about the cars. I think my fan is in good shape but I am going to look it very closely this weekend!
Kris

gristle101

Ah sh*t. I didn't even stop to consider the pulleys; I just thought, "all one system stemming from the crank, all spinning equally". Never even crossed my mind. I guess I'll have to measure the radii of the pulleys and redeem myself with "fun with numbers"

HalV

Will do...I wont be tackling any big jobs until after 2nd week of June.

LPMM

Anyone used this gizmo for that job? I called Snap-on to figure out the overall length in hopes that it will fit, but they don't have any specs.