Got a few ideas...... are sure you want to hear them? If the fan clutch & fan are relatively new it would be unlikely they could be defective , but not impossible. Are you positive you have the correct fan & clutch installed? The fan roar could be the electric fan cutting in due to elevated temperatures. Perhaps the electric fan is cutting in early or late due to a defective/damaged or incorrect sensor. You are more likely to hear the electric fan operating in comparison to the fan on the water pump.
"Also 'locks up' for the first minute or so after a cold start and then slows down." That's normal! :bash: When the engine is stationary & cools down, the silicone fluid drains into a section of the clutch causing it engage when it first starts spinning.
I can hear the roar of the air movement from my viscous when it gets going, normally only from outside the car though - inside maybe if its idling at the lights - I figure this is what people mean when they say they hear the viscous fan roar, not the fan so much as the air being moved
I have spent a bit of time trying to improve the cooling system on my Zed and have a few interesting thoughts on it. I originally changed to a different grade of fluid in the viscous fan hub and had what I felt were good results. I had a great original radiator that I did have rodded when I bought the Zed years ago. I can say I have never had a problem with over heating but have always wanted a good cooling system. I only drive the Zed a couple of days a year but it is usually on 30 + days. So I bought a aluminium radiator made by Wang and put that in. Really no difference. I seem to get temperature rises at speed up to 96 but no problem in the city stuck in traffic. I have all shrouds and a vented bonnet and are starting to feel the vented bonnet actually makes it worse at speed due to upsetting the air flow so in the future I will put the original bonnet on to see what happens. Recently I put a new pump in and also a low temp thermostat and new viscous hub and get exactly the same rises at speed. After doing this I even pulled the front plate off on the way home to improve the air flow (have a Abflug bumper with a wide mouth) but still the same . I use a good coolant so no worries there. I drive an old Land cruiser at work and the interesting thing with it is the viscous fan roars it tits off when accelerating which the Zed doesn't. I'm almost thinkingof seeing if one will fit the Zed to compare. Any way this topic interest me greatly so thanks all for contributing. Dave
If you get a huge difference in coolant temp with AC on, have you had the auxiliary fan ecu mod? and checked it is working? It helps. (can't remember if it was Mike or Ian that put me onto that mod or another but thanks again) PS, to let some hot air out of the engine bay, try that washers/spacer idea to raise the back edge of bonnet (and remove the rubber on back edge)
Pretty sure they're the right parts - purchased from Coz but I'll check to make sure. I have my Adaptronic ECU set to turn on the thermo fan on at 90c so I know pretty well when I hit that point. Coolant temp sensor is new as is the plug (CTS operating perfectly confirmed with extensive data logs while i've been tuning the ECU over a year or so...) The thermo fan is a very distinct noise from the roaring noise of the viscous fan moving large quantities of air, and not as loud IMHO.
Is anyone interested in actually testing this properly? I'll front up the $$ for balometer hire, are there any volunteers in Sydney who are interested in donating a day of their time? I'd need a car running a standard clutch fan and a car running an electric thermo fan. Preferably both with similar size radiators.
I think it would be pointless testing a standard aftermarket fan vs clutch fan, we all know the clutch fan will outperform it easily. A better test would be John's setup with the Taurus or similar fan, installed and setup correctly vs the clutch fan.
How about this one with 16" Spal? I can quite easily drop it into a test car and run it straight off the battery. Don't need switching etc if we are simply measuring max cfm.
I am not going to say that there are no thermo fans that can do the job, it appears that the one posted in another thread seems to do it fine for his build and I am not going to dispute that at all, the issue here of course is the availability of Taurus parts, are not anywhere near what they would be North America and its a hell of a gamble to try with alternative parts when so many off the shelf units have proven unsuitable. This said it would be great to see a back to back test, the issue as seen with other tests (Mungyz 2.5 intake test is one that springs to mind) is that unless one goes to stupid lengths there are always going to be those that doubt the results and hate on them even. Which can make the person testing often wonder why on earth they tried to do us the service at all. With all the options available I can see the person doing the test getting a lot of negative response and unless it comes out a resounding affirmative infavor of the thermo fan being told "We told you so" and if it does come out that way people saying the figures are wrong. please note I believe truely that there would be a thermo setup capable of working in our cars, there are many cars out now with thermo's and turbos and tight engine spaces that make it work (check out some of the BMW's available) that we can not be the exception, the fact however that our viscous fan works so well is a good enough reason for me to leave it as such.
