Tuesday, May 20, 2008

Porsche 964 Temporary Cooling System Fix

You may not know the other side of me yet, but in case you are curious, I pride myself as a bit of an engineer. I actually went to school for that as you will remember. Problem: Porsche 964 Oil Cooler Fan not engaging. Fix, after 6 steps of diagnosis (1 year): replace Controler Unit. These CCU's cost $1000.00 Candian to replace, if you can find one. The current solution is to 'watch' eBay, and hope. Here is my ad hoc solution, which I stole from an internet post. I intend to actually refine this and advance this proposal. I will post it, if successful for all of the Porsche 964 and 993 owners out there.
Basically the theory is simple. The CCU puts out some sub volt current when it thinks your oil cooling fan should switch on. If you have a defective CCU, (BMW, Mercedes and Porsche owners), that signal never actually reaches the component it needs to. An intelligent chap had a hypothesis back in 2005 about delivering the neccessary voltage to the 'relay' that engages the fan motor. His math was seriously off, as he used 12 volts as a base voltage for his charging system. Due to my nautical and automotive background, I have corrected his error and modified his theory a little. All you have to do is put together a fused (1 amp) resistor circuit with a 6 ohm resistance value and apply it across pin 6 in your Porsche fuse box, Relay 4. It's so easy. I spent $5.00 on this. I will apply myslelf this weekend to a more sustainable fix, in that I will encorporte a switch and a two speed fan option using existing unused Porsche factory wiring.
G is expected at the end of August. I want everything in order when she get here!

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