Fan alternatives?

[GRCameron]

I'm kind of skeptical of the nylon cooling fan on my 710. I've read in the forums about several fans exploding, or remnants of exploded fans found inside the cooling shrouds. I have a first-hand account of an explosion from a friend who had one come apart while checking the performance of a Pertronix Ignitor during installation and test running. New replacement fans are VERY expensive through SAV - I wouldn't consider purchasing a used one.

Will an 11-blade Porsche 911 cast aluminum fan fit the Pinz? They look alike and the major difference I can see is that the Porsche fan doesn't have the holes for the pin spanner wrench - they are in the pulley itself. The Porsche 911 engines have a rev limit of somewhere between 7000-8000 rpm, so the 911 fan would last "forever" on the 710 with 4500 rpm rev limiter (assumes similar drive ratio on the pulleys).

Porsche part# 930 106 012 00

[Stekay]

I don't recall ever hearing of anyone on the forum having lost a fan unless crossing a stream. It's true that our trucks at ~40 years old are probably more brittle than when new and prone to a failure if damaged in some way. The Porsche fan is an interesting option at a similar price. Have you done a search for propellers/fans? I'd imagine there is an adaptable industrial piece out there somewhere. I guess it comes down to what your time's worth.

[undysworld]

I don't recall ever hearing of anyone on the forum having lost a fan unless crossing a stream.

Now you have.

Mine blew while crossing my driveway (well, actually going up the driveway and approaching the road). It was a substantial explosion, leaving the doghouse cracked clean through and embedding fan parts into the underside of the doghouse.

Since then, I'm extremely leery of even running the engine without the doghouse cover installed. I do it. You have to. But I'm nervous as a cat when I do it. (I've lost two friends to felled trees, and I think of them EVERY time I drop a tree. It's the same level of nervousness. It's kept me alive, so far.)

I've considered building a "blast shield" to install over the fan when I need to run it open, but haven't actually gotten around to it. I'll probably find the time when I'm picking fan pieces out of my forehead someday. As they say, there's never time to do it right, but there's time to do it twice.

I'm reading along, and interested!

[Stekay]

WOW! And I'm assuming you weren't at very high RPM. Did you have the fan break at the hub and come out of the surround or did you just lose blades. You have me thinking of a mod with a coarse screen in front of the fan and and a kevlar wrap around the surround duct. Glad it missed you!

[undysworld]

Nope, mid to low RPMs. Actually, I'd just pushed the clutch down and the engine was slowing down at the end of the driveway. With no warning, WHAM!!!! (Think 12 gauge going off in the truck!) Blades and big parts of the central fan section let loose too. I honestly thought the engine had grenaded, but then my hearing returned and I realized it was still running okay.

A few pieces went forward, but apparently not with much velocity, as they were found laying in the tunnel. Mostly centrifugal force threw everything straight outward radially.

Somewhere along the line, somebody showed photos of a tin shroud which went from the tunnel to the engine tin, and covered the fan completely. IIRC, it was a rare factory piece. I like the idea of a kevlar shield.

I do believe catastrophic failure is very rare with these, as I've been here 12 years now, and I just don't remember many people writing about problems. But if my face had been where that doghouse was...

Perhaps tellingly, Jack Raby (R.A.T.) is no longer willing to balance Pinz fan blades (or at least refused to the last time I inquired). He said he was afraid of damage to his machine if one did let go.

[GRCameron]

Perhaps I'll buy one of the Porsche fans and report back on the results. It will have to wait until Christmas is over, however, due to lack of cash.

If it doesn't work out, there will be 1 more used Porsche 911 fan for sale on ebay...

[Profpinz]

I'm kind of skeptical of the nylon cooling fan on my 710

I heard of people worrying about the fans before but in all my years of owning/driving my 712 I've never had any problems......I've had the fan submerged a few times (boy, is the Pinny quite when that happens) but still no problems.

[McCall Pinz]

Wow, there must be some truth to ESP. I had a long drive today and was thinking about this too. Mostly I was concerned about proper balancing and reducing some engine noise. I recall an earlier thread saying the 911 fan won't work though...

[VinceAtReal4x4s]

I would think that buying a new stock fan, which would not be brittle and likely last for the rest of the life of the Pinz, would far outweigh any benefit possibly gained by experimenting with a non-standard part that was installed without it being engineered for that exact application. Not to mention saving an enormous amount of time, tweaking and worry.

[GRCameron]

I did some further digging in the old posts and found that someone had already researched this. The 911 fan is 2" smaller in diameter than the Pinz fan, so it's a non-starter. I do like the idea of a cast aluminum fan, though.

[Stekay]

Rapid prototyping!

[krick3tt]

this would be a great time to bring a 3D printer and make one!

[spandit]

There must be loads of normal electric fans of the right diameter that could be separated from their motors and adapted to fit.

3D printer would be good, though...

[rmel]

The fan belt drives the fan and alternator, good luck on an electric motor fan.
That's more like perpetual motion, or cold fusion

[spandit]

Please read my post before making smug comments. I mentioned separating the fan from the motor and adapting it to the front of the alternator. I've made a new pulley for mine anyway on the lathe so for a competent engineer it can't be too difficult