Thread: I need every possible option laid out in front of me,

Originally Posted by mrwoody1985

Car hasn't been started since yesterday so I went out ant started it, let it idle for about 2 mins listening, I could hear it sucking a lot of air through the air flow snout, but as for any air related noise from clutch fan area nothing changed, so it's fairly noticeable? What part does the viscous fan play? (that's the alloy section behind clutch fan?)

A viscous fan is a cunning device when it works properly but a pain in the arse when it doesn't.

What happens is this. The inner mounting hub of the fan has no physical connection to the fan hub itself. It is filled with a 'special' oil. This oil gets thicker when it gets hot. (This is the tricky bit as most oils get thinner when they get hot). So when it's cold the oil is thin so there is little friction between the inner hub and the fan hub so it does not rotate. As the engine heats up so does the oil which 'solidifies' and effectively connects both the inner hub and the outer hub together so the fan is driven. Normally it just free wheels with the air flow. DON'T try and grab it to find out.

What happens is that the viscous oil leaks out or loses its efficiency and the fan does not drive, it just freewheels and does nothing to move air. This is a very common problem. Viscous fans NEVER fail locked on.

The easiest way to test if a viscous fan is operating correctly is to let the fluid settle (say overnight) and start the engine. Because the engine is cold and the oil thin the fan should not drive but it does initially as the oil has all sunk to the bottom in the fan hub so the fan will drive initially until the oil is evenly distributed throughout the fan hub and then dis-engage. This usually takes 15 to 30 seconds and is VERY obvious.

If you are standing by the engine, bonnet up, when it is started the fan should be engaged and the air flow is loud and quite breezy to the feel if you put your hand WELL BEHIND the fan or lean over the engine. It is also quite noticeable when the viscous fluid has spread throughout the hub as the air flow and associated noise decreases substantially.

Try it on a known good engine, once you've seen/felt it you'll know.

Deano

cheers deano, makes more sense now! i ran the car for about 5 mins, until the thermo fans kicked in! and there was no difference until the thermos kicked in! BUT i felt the radiator after running it for that 5 mins and the top half (fins) were hot and the fins at the bottom were still cold! blocked radiator?

I still don't think you have answered the main question - IS it getting hot, or just moving up and down on the (not very accurate) dash gauge. Hot at the top and cold at the bottom is sort of what a radiator is supposed to do...

Do you have access to an infrared thermometer? If so, do a few checks at different loads, and different temps to see what it is actually doing - you may not have an issue at all...

Not sure where you are at, but if you live in Melbourne, I can pop around with mine at some stage and check.

I'm in Nsw bud, but yes as I stated earlier it boils over if given the chance, so it can't get much hotter, there has been 3 times it's boiled over when I couldn't stop in time (off road climbs)

If your aircon is off and your fans come on at idle soon after starting then you have problems. As someone said above they only come on as a last resort when your engine is running hot.

If your water pump is leaking from the bottom hole then replace it. The bearing is on its way out.

Also be careful hitting any cooling fins with a high pressure hose. You might bend them.

pull the radiator out, go get it rodded, put it in and see what happens.
At least then you can tick it off the list.

Sounds like you viscous fan is stuffed. However it will mostly help at low speed, at highway speed the air flow alone should be enough to keep the cooling system temp below thermostat temperature. So it appears that your radiator is partly blocked and/or your water pump is not doing the job.

Pull the radiator and get it looked at, replace your pump, it sounds as though it is on its way out anyway and replace your viscous fan. And if you have cooked it a couple of times get ready to do the heads.

just give the whole lot (rod the rad, clutch and pump) a service, parts are cheap and then you know what's new.