Hi. I have a petrol townace with a 3y engine.
after many attempts at trying to solve an engine
overheating problem (radiator flush & check, new thermostat, new radiator cap)
I then desided that the old fan was faulty and ordered
a new replacement, this was fitted but i am new still having a problem.
When the engine temperature gets hot i do not hear the fan cutting in. (and the temperature still rises) also at that point when i switch off the engine the fan still rotates as if it has no resistance

My question is can a brand new Viscose Fan be faulty ?
and is there any way to check it out.
- (#9873) carol dodds, 8 Aug 03 15:32

Carol. The difference between "slipping" and "driving" seems to me to be very close on these viscous couplings and, when you switch the engine off, and test the resistance of the fan blades, they do seem to turn quite easily. It is a misconception that they "lock up" and I think that, with no heated air, being drawn over the fan coupling,even though the engine has just been stopped and is hot, the thermostatic valve, which opens under the heat being drawn through the radiator, soon closes again.
You can only test these fans properly when they are running and when the fluid, inside the coupling, is being thrown outwards (inside the casing) and driving the fan blades. Have a look at the "cotton" test in Ace Answers. Tie a fan blade back with a single piece of cotton or thread. Keep you hands away and, as the engine/radiator heats up, the thread should break and show you that the coupling is doing it's job. If it does not break, yes there is something wrong with your coupling but, on a new unit, that is unlikely. You can drive with the passenger seat up and observe the fan but, as it is always turning, this is a bit difficult unless, as the temperature rises, the fan stops turning, indicationg a malfunction.

- (#9874) John Davis, 8 Aug 03 15:52

Also - if you can stand the intense heat - drive on a long road with the engine cover up and you will note and hear whats happening - (use earplugs also) - but bear in mind the engine will run a little cooler able to lose its heat in the cab and out the windows.
I used to find that 1st thing in the morning it would roar for a short while - indicating it was doing its job - also try driving in very hilly areas wher the engine can labour with a window open listening.
I think also that any airlocks in the cooling system would slow the flow through the rad which would mean it wouldnt heat the viscous properly - so would check this out if worried.

- (#9875) chris turner, 9 Aug 03 6:27

Another 'loose' test - with engine off and fan able to spin freely - pour a kettle or two of boiling water over the alloy coupling (directing over the metal spring at front if possible) - this should heat it up enough to line up the internal ports - spin it some more in its usual direction and the fan should stiffen up ie
not spin as freely

- (#9876) chris turner, 9 Aug 03 9:06

The performance of a working fan is progressive. Once it has reached the end of this progrssion the blades are locked to engine speed - hence to noise at full fan operation - the fan shifts a great amount of air drawn through the rad. As this air cools the fan should drop back down to a slower speed. Just have a drive around with the cover up and you will feel the air push when it comes, fit a Dave Mason Temp Alarm ( amust have in my opinion) and you will see the guage change in relation to fan speed.

- (#9877) Clive, 10 Aug 03 1:49

Apart from improving my temperature gauge all I've ever done to my '91 4WD Royal Lounge's cooling was a very thorough flush when I bought it two years ago and fitting a normal "long" number plate on the front bumper.
I seem to be fortunate in having an engine that stays at the thermostat-controlled temperature - shown by the modified gauge. There were a few exceptions in last week's heat but I've never been aware of the fan making a real "roaring" noise though I suspect there are times when the viscous coupling does pick up the drive, only to slow down again as soon as it takes effect.
Having made available the temperature gauge solution, I'm wondering about a robust marketable gadget to meet the evident need to measure and indicate the speed of the fan rotation, or of the airflow though it. Any ideas?

- (#10183) Dave Mason (Sussex), 11 Aug 03 10:58

Hi Dave

When I first owned my Townace, I had thought the VC wasn’t working properly so I built an anemometer using a motor from a cd drive, (the one that operates the draw) and an old toy helicopter blade. This produced a fairly low voltage, but was able to show the difference between an idling fan and a boosting fan, when hooked up to a millimetre. Sadly it fell apart after only a short time.

I had meant to develop it further, by finding a better fan assembly, and connecting it to a bar graph that would light up one segment at idle, and all ten when the fan is engaged, with the engine revs at 3000. The birth of our son, and lately a cracked head have forced it from my mind.

dave Bright

- (#10184) dave Bright, 11 Aug 03 12:24

Page 202 of 'machine mart' catalogue show some hand held tachometers - also could consider ideas based on the modern cheap push bike speedometers - or strobe light timing guns. Think you have it very well covered with the temp guage mod though

- (#10185) chris turner, 11 Aug 03 13:27

Whenever I driving my car(1993 Infiniti G20, 5 speed manual) in 1st, 2nd or 3rd gear and then whenI am slowing down the back of the car makes a roaring noise. I have checked the brakes(fine), rotors(fine), the tires(need new tires) and it is all fine. I was wondering if this will be tranny problem.
Thanks...

- (#10713) Shanty, 1 Sep 03 14:49