I've recently replaced my Viscous Fan with a 12" electric fan. I mount it in the middle of the radiator hard up against the radiator. No cowling here.
My problem is that if I sit intraffic the temp goes 3/4 up and doesn't come down when on the open road. If I plant it, say up a hill, the temp goes up and stays there. In both cases the temp doesnt come down if I get on to a highway and cruise. It only comes down if I switch off and leave it for a while.Any ideaswhat could be causing this? The fan comes in at 82degrees. Do I need a second Fan or Do I need to move the fan lower too pull some air thru the Oil Cooler, but then the effency on the radiator will go down. HELP

 

Well, it sounds like your fan is a bit small, and you will need it to cover the oil cooler as well. However, the fact that it doesn't cool down at highway speeds would suggest a flow issue.

 

I had the same problem with my FC, put the stock system back on, everything is fine now.

Your fan is too small and the stock system works quite well.

 

Do you have a dual belt system for your alt. and water pump? Its a must.

 

Why did you pull the OEM fan? It's unlikely that an EFan would work better, so it's just wasted effort, IMO. The OEM fan cuts out before you get into the powerband, so you won't gain any HP, as near as I can see.

I'm running 4 rotaries and they all have OEM fans. I've done other work on each ones cooling system as required (new water pump, radiator, hoses, T-stats, etc.) but the only problem I've had with the fan is one that would stick sometimes and keep whooossshing as it revved. Easily fixed with an $8 replacement from Pick 'n Pull.

If your rotary is overheating then your fussing with the fan may be masking some other cooling system problem.

B

 

I don't know, I like my fans. Quieter, crisper low speed response, cleaner looking engine bay....

 

OEM fan was dead, siezed and blades all chewed up from throwing belts. Haven't had any belt problems since the electric.

 

Might sound like a dumb question, but have you insured that the fan is actually pulling air thru the radiator? Even though a 12" fan is small, it should be capable of handling just about anything short of extended stop and go traffic.
Your statement about it not cooling back down after getting it moving makes me think you may have the fan wired wrong.
Of course, you could have a faulty gauge or thermostat as well.