Clutch fan importance

[Darwiniandude]

This post is more for my own notes than anything, as this is the first car I've had with a clutch fan that I've had overheating issues with.

Not the resistor problem as it only happened in these conditions.

The car would, on a 30+ day, get to 3/4 when slowly climbing hills, or stopped in traffic. At one point, I started to hear detonation beginning.

Replaced Radiator, thermostat, full flush and bleed of system, also new plugs and plug sleals.

It still had the issue.

I bought a clutch fan from a wrecker, it seemed gripper than mine. Not familiar with how these should feel.

Then I had a good 6 months of cold weather and couldn't test it.

During the colder weather, I bought two bottles of Toyota clutch fan silicon oil from eBay, just in case.

When the hot weather returned, I slowly climbed a steep hill at 20kph with the Aircon on, on a 32 degree day. Temp climbed a lot. I turned off the aircon and went down the hill fast, the airflow brought the temps down.

That night I rebuilt the clutch fan with the lil from eBay. But two bottles wasn't enough to fill it once emptied of the old oil. This silicon oil deteriorates over time.

The next day which was hotter, I tried the hill again. It worked brilliantly. On a cold start I could hear the fan loudly, then it quietened down. Going up the hill slowly in the heat, the fan worked loudly, temp stayed normal. Awesome.

But... This was a few weeks ago. Yesterday it reached 41.8 here, today it's meant to be 43. Ouch! Yesterday in stop start traffic, the gauge climbed again. But the fan didn't sound like it was working as hard as it should be.

Mitsubishi said a new clutch fan would cost $509 would have to come from Sydney. Repo said there was one in Adelaide for $331. I called another Repco for some reason, they said the part was on special and I could have it for $180. This is for the correct Dayco part.

Well I just picked it up. (will install before driving home tonight)

Wow.

There is a HUGE difference in the feel of this unit. When cold, turning the spindle with my hands is almost impossible, it is so tight. After 30 seconds or so of wrenching it around with my hands it starts to loosen, and then when you keep at it it becomes so freewheeling that you can easily spin it around by itself. (This is inside, heavily aircon'd room)

Anyway, from the difference between the refilled fan and the original, and then how this feels, I KNOW that this will fix my issue. A brand new fan clutch feels very different.

The box states that after four years or 80,000 km that these kind of overheating issues can be caused by the fan clutch needing replacement.

I have a feeling this is often overlooked a bit with these cars, as the refilled one did test ok, but...

Anyway, proof is in the Christmas pudding. Will update once driven home.

[wrexy]

Enjoy the heat. We had two consecutive days of 45c. Who says Global warning does not exist ?

[dookie]

Those prices are ridiculous. I needed one earlier this year (at ~190k miles! ):

Bought this one...works a treat!

[Darwiniandude]

Those prices are ridiculous!

And that's why we import a lot of stuff from the US instead of buying locally...

But in this instance, I needed it ASAP. Cheaper to pay an extra $100 or so than to cook my engine.

[rotare]

Interesting. I thought I read somewhere that after say 40km/hr the effect of the fan on the cooling system is minimimal, because the air flow through radiator from the car travelling foward is greater than what the fan can draw. Just wondering if someone could clarify?

Obviously if your car is overheating whilst stationary the fan clutch is probably the culprit, but I wonder how much effect the fan has at speed?

[hiedipro]

Interesting. I thought I read somewhere that after say 40km/hr the effect of the fan on the cooling system is minimimal, because the air flow through radiator from the car travelling foward is greater than what the fan can draw. Just wondering if someone could clarify?

Obviously if your car is overheating whilst stationary the fan clutch is probably the culprit, but I wonder how much effect the fan has at speed?

Try this site for more info.
forums.pelicanparts.com/bmw-6-7-8-series-technical-forum/512843-how-test-visco-fan-clutch.html

Also I put some info on an earlier post.
http://www2.pajeroclub.com.au/forum/...ght=fan+clutch

[Pauly Faulkner]

It has a fair amount of work to do even at speed. Mainly when foot is on the gas.

When testing by hand with the unit out, poor hot water over it then turn a few times. It takes a dozen spins or so for the fluid to get back to where it's meant to flow to.

If I'm not mistaken the fluid control valve that is operated by the bi-metal strip is adjustable internally and when you put new fluid in you can adjust it to let more or less fluid through..?

[hiedipro]

It has a fair amount of work to do even at speed. Mainly when foot is on the gas.

When testing by hand with the unit out, poor hot water over it then turn a few times. It takes a dozen spins or so for the fluid to get back to where it's meant to flow to.

If I'm not mistaken the fluid control valve that is operated by the bi-metal strip is adjustable internally and when you put new fluid in you can adjust it to let more or less fluid through..?

if you read my earlier post as indicated above it will show the manufacturers sequence of testing.
The bi-metal strip is on the outside on most & operates a plunger into a valve inside. When stationary overnight the fluid drains into "drive area" (like a torque converter has vanes in outer perimeter).
On startup the engine pumps this oil back into the centre resevoir & the fan frees up, may take 1, 2, or 4 minutes.
After engine has run a period of time & water temp is near operating temp, then the bi-metal strip will have finished operating the plunger, which opens the valve, which lets the fluid be propelled by centrifigul force to the outer "torque converter" area, so locking up the fan.
Of course there is a little bit more intelligence built in to optimise road speed - ambient temp - revs - noise - etc, but the above should help understand the steps for testing.
Hot water (70'C) has limited value. It only tells you the strip is working but not whether it is operating in the right direction ( yes, I have found one in back to front), or that the fluid is moving, or that the valve is working. All of these only show up with the centrifugal force of a runnning engine.

BTW generally you can only adjust the bi-metal strip if you know what to adjust to. And you can refill some through a plug or you can drill & tap your own plug. But you need to drain till you have it all out so you can measure the same back. DO NOT FILL.

[Darwiniandude]

Ok, I am absolutely stoked.
I am the proverbial pig in

Very happy.

Driving home the gauge sat a needle's width below half way the whole time. Even driving up The Nasty Hill I Avoid Because It Makes My Pajero Overheat.

40+ temps, Aircon on, slow moving congestion and this long 60km steep hill (North end of Southern Expressway for those in Adelaide) it didn't move once.

Awesome.

I shot a few short demo videos of me talking to myself about the fan noise, I'll cut these together and add it to the thread. You can really hear the fan now. I'll take it for a long downhill session in the cool of the evening somewhere to check the fan is disengaging ok when it's cool.

So happy.

[hiedipro]

Ok, I am absolutely stoked.
I am the proverbial pig in

Very happy.

Driving home the gauge sat a needle's width below half way the whole time. Even driving up The Nasty Hill I Avoid Because It Makes My Pajero Overheat.

40+ temps, Aircon on, slow moving congestion and this long 60km steep hill (North end of Southern Expressway for those in Adelaide) it didn't move once.

Awesome.

I shot a few short demo videos of me talking to myself about the fan noise, I'll cut these together and add it to the thread. You can really hear the fan now. I'll take it for a long downhill session in the cool of the evening somewhere to check the fan is disengaging ok when it's cool.

So happy.

h heat will
I am happy for you too. The is so easy to overlook because it LOOKS to be going OK.
A downhill in the cool sounds like an idea but may not tell you much. The water thermostat will try to keep the water at 90'C regardless of ambient so enough heat will flow to fan partly engaged.

More accurate test recommended:
1. In the morning when fluid has migrated to bottom of hub the fan should be stiff, because of time, not because of cool.
2. Because it is cool, fan will turn at speed of engine idling for 2-3 min.
3. After say 2 min, or a little after you hear fan noise die off, stop engine with someone watching fan. It should now spin on freely.
4. After you have done some driving & engine at normal temp, switch of engine, again with someone watching. Fan should stop with engine, or, most specs say, spin a max of 3 turns.
I am sure you will find it all good noww.

[hiedipro]

Ok, I am absolutely stoked.
I am the proverbial pig in

Very happy.

Driving home the gauge sat a needle's width below half way the whole time. Even driving up The Nasty Hill I Avoid Because It Makes My Pajero Overheat.

40+ temps, Aircon on, slow moving congestion and this long 60km steep hill (North end of Southern Expressway for those in Adelaide) it didn't move once.

Awesome.

I shot a few short demo videos of me talking to myself about the fan noise, I'll cut these together and add it to the thread. You can really hear the fan now. I'll take it for a long downhill session in the cool of the evening somewhere to check the fan is disengaging ok when it's cool.

So happy.

I am happy for you too. The is so easy to overlook because it LOOKS to be going OK.
A downhill in the cool sounds like an idea but may not tell you much. The water thermostat will try to keep the water at 90'C regardless of ambient so enough heat will flow to fan partly engaged.

More accurate test recommended:
1. In the morning when fluid has migrated to bottom of hub the fan should be stiff, because of time, not because of cool.
2. Because it is stiff, fan will turn at speed of engine idling for 2-3 min.
3. After say 2 min, while engine still cool, or a little after you hear fan noise die off, stop engine with someone watching fan. It should now spin on freely.
4. After you have done some driving & engine at normal temp, switch of engine, again with someone watching. Fan should stop with engine, or, most specs say, spin a max of 3 turns.
I am sure you will find it all good now.

[Darwiniandude]

Thanks for the tips. Yeah, a cold start test after a few ministers seems like a good idea. I'll do that tomorrow.

Before I installed the clutch, I manually twisted it in my hands for a few mins and got it to ease up and eventually spin freely. This was in a room with nice air con. So I reckon it's ok.

[Darwiniandude]

A bit pointless, but here is the iPhone video I made today after installing the new fan clutch.

http://www.youtube.com/watch?v=R8t7yUS19CM

There are a few points where you can really hear it screaming.

[Pauly Faulkner]

Sounds like the new one I put on mine last summer. Roars off it's head for the first minute or two when accelerating down the road first thing of a morning.
Tha last one that was stuffed did the same thing but just did next to nothing after that.

[hobbo]

Thanks for the good info about those clutch fans, it certainly made a big improvement and we had the Perfect Day for Testing it out yesterday too ! I am still a bit concerned about your Radiator, I don't think it should have Allowed the temp to rise so much even with the clutch fan not working well ? I'm not sure if these radiators block up when running coolant all their lives ? I know the NM had some problems with radiators being blocked.