The fan clutch that was on my car (s4 non-turbo) when i bought it died a few weeks back. All of the fluid came out. I bought a never used s4 clutch that turned out to be DOA (can stop fan with newspaper).

At this point I think my options are: 1. Junkyard surfing for more s4 clutches
2. Get an s5 clutch.

Would rather not get another S4 clutch since they are all 26 years old already. What does it take to put an s5 clutch on an s4 car? Will I need an s5 fan blade? S5 water pump or water pump pulley?

 

IIRC, A S5 clutch fan should just bolt right onto the S4 pump pulley. But as you said, a clutch fan for a FC is already quite old and has quite a few miles on it. Granted, they are more reliable than an E-fan, due to fewer parts involved, but age never sleeps on parts.

Are you familiar with the various junkyard electric fans that are used? Some guys use a single speed one such as the Fiero Fan (Aaron Cake uses one). I personally use a 2-speed fan from a 3.8L Ford Taurus, along with its alternator as it is a very thirsty fan. But for the results it generates for the small input price, the Taurus Fan is very difficult to beat. The Second Generation FAQ has a link to how to wire one up correctly.

 

water pump spigot size change between s4 and s5


the s5 water pump locator diameter is larger so it will float around on the s4 water pump snout and not be hub centric

 

How big of a difference is it between the s4 and s5 pump nose? Would a spacer take care of it?

 

Putting a spacer on will compromise the water pump bearing.Adding extra load to the bearing will wear it out faster.
The s5 fan has 10 blades on it while the s4 has 8,So if you are replacing the S5,do so with an S5.

This is one of the things you do not want to take for granted.Water cooling is essential on these engines.

*by the way the S4 and s5 pumps are not interchangeable onto the other series housing.
The Bolt patterns are not the same.The pumps (s4 onto an s5 or an s5 to an s4 housing) will not fit.