New fan clutch does not pass rolled newspaper test

[325e '87]

My fan clutch just siezed up on me, it remains at full lock all the time. It's loud and seems hard on the engine.

Do they typically seize up when they fail? I've never had an issue with it and never had any temp problems with the engine so this feels like a random occurrence which makes me nervous for some reason.

[dnguyen1963]

If your temp gauge moves randomly to 2/3 near the red zone then I would check your SI and main board for corrosion instead of the fan clutch.

[LJ851]

If your temp does not climb and continue to climb to overheating, your fan clutch is working.

[mrsleeve]

Sounds like an air bubble in there to me ...............


This is a very general an basic explanation of how a fluid clutch works. There is a bi-metal spring gets warm and turns a plate with holes of increasing size on it and saw like teeth on it. On the housing side there is another set of teeth and ridges that align with the holes in the plate. There is a very thick fluid (normally silicon) that wants to stick to it self and has a very high shearing tolerance. When that bi-metal spring turns the plate far enough inside so the holes align it lets the fluid pass to the inner part of the housing and engage against the ridges.

Since the fluid wants resist this sheering action it effectively locks the the 2 together softly. If you continue to push things and the spring gets hotter, it will turn the plate more until and line up more or bigger holes allowing more fluid to become involved and resist even more sheering, and transmit more power to the fan plate.

Now if you cooling system is working correctly your fan clutch may never get warm enough except under extreme duress to actually turn the plate far enough to start the lock up process or it might just barley need to start to get enough fan speed..

Now when you let the car sit for a few hours all that fluid pools at the bottom of the clutch thanks to gravity, so for a few moments when you 1st fire up the engine before the fluid is evenly slung around where it belongs you have a full lock up condition.

Check you clutch at this time to determine if there is 1 enough fluid in there (the FJ80 guys have issues with this with new ones sometimes) and 2 that your fluid is just not plain wore out. If you are not actually over heating then I doubt you fan is an issue and I would be looking in other places 1st. Like the pressure cap, non OEM t-stats can cause fits, an air bubble still in there (you did drill you tstat when you replaced right ) or finding the pin hole leak someplace that is not letting your cooling system fully pressurize. If your old fan clutch was actually bad then by all means keep the new one, and its possible you got a bad one form the factory, but I suspect you have more than 1 issue at hand and a fan clutch will only mask cooling issues for so long.

fwiw. the spring in my new clutch in my landcruiser was factory set to start opening at about 118F AIR TEMP (I rest it to 95ish 1FZ's make a kot of heat). Coolant temp has no direct correctional to fan engagement, under hood AIR TEMP is what determines when the fan locks up. Now if your rad is not working efficiently and not shedding heat well due to a whole host of factors it heat soaks and the air coming though back under the hood is hot there by raseing the temp of that little spring, making it lock up and SUCK more cool air though.

[Madhatter]

The clutch fan doesn't lag much at all because of its location. That and the fact that the thermostat takes a period for it to open fully, its not simply open and closed. It's pretty universal with all cars that the thermostat being fully open and the cooling fans kicking in is roughly similar.

If you want a specific temp for the clutch fan its going to vary a few degrees to start with anyway, then vary between new and used as it starts leaking some of the silicone fluid from the hub and the lockup changes.

This really should be a simple non issue though because you can't really mistake when the clutch fan is engaged. It's like night and day.

[digger]

The fan engagement will lag behind the thermostat due to thermal masses and heat transfer so it will take a period of time afterwards. In no way is it as simple as a certain coolant temp there is a time factor to. Halfway on my gauge is 95c so it would have kicked in for sure

[Madhatter]

Its when the thermostat is open, thats the point of the fan. It's one of those automatic basics for all cars, rough point for cooling fans is when thermostat is open.

If its more than 4-5 degrees different in your ratings ill be very, VERY surprised. 80 degrees celcius standard for the thermostat? Thats 80 degrees when it begins to open, not when its open fully. Fully open can be another 15+ degrees more. When do you think the fan engages the clutch?

If both your hoses are hot the thermostat has to be open and flowing coolant freely. It can't bypass coolant any other way.

if you reach 2/3 on the gauge and your auxillary fan on the front (the AC one) hasn't kicked in, then id be suggesting you might have issues. It's somewhere in the high 80's to low 90's for when the high speed fan switch activates on the radiator and will turn the electric fan on too. So by that point all fans should be running and the temps should be coming down.

If things are running right and you don't have any leaks, etc, I never normally see M20 cars pass 1/2 on the gauge when running. When everything is brand new, I tend to find them running around 1/3-1/2 is the normal spot. If the clutch fan has engaged hear you will see/feel it. Pull over next time the temps reach this and open the bonnet. If you rev the motor you can literally hear the fan speed up and down as there is a bit of delay. If you can't feel it, send it back for a replacement. They aren't going to go bolt it to a car and test it themselves if you say your car is getting hot and you can't feel/hear the fan running. If you still have your old one, Place two self tapping screws through either side of the front middle of the hub. Where the bimetalic strip is across the front. It'll lock the hub solid so its engaged all the time. Put it back on and start the car. You should instantly know what the fan sounds like when the clutch is engaged.

if your rad hoses are hot top and bottom and you don't have air blasting out, you've got issues with it creeping to 2/3 on the gauge. What is your heater core/tap like? no slight leaks under the carpet? radiator cap all good and sealing too?

[GoldMember]

is it overheating when idling?

No. I've noticed it randomly moving to the 2/3 line on the temp gauge while driving. By randomly I mean, less than 50% of the time and in all different ambient temps. I've got a brand new Behr radiator and the thermostat is less than a year old (Behr also, 80 deg).

[whodwho]

is it overheating when idling?

[GoldMember]

Rough point is basically when the thermostat is open. So if you grab the top and bottom radiator hoses and they are both hot to the touch, the clutch fan should have engaged and air will be blasting out over the motor.

I don't feel like this is the case.

Lots of different answers to this question here! All of them make sense but I need something a bit more definitive if I'm going to contact Autohaus AZ about a replacement. Right?

[Madhatter]

Rough point is basically when the thermostat is open. So if you grab the top and bottom radiator hoses and they are both hot to the touch, the clutch fan should have engaged and air will be blasting out over the motor.

[digger]

Yes, I don't mean that is when it Kicks in but it well and truly should have if its close to that

[GoldMember]

turn engine off and point at the fan hub to see what temp the alloy housing is. if its at 95C it should be working. also check the themostat housing and rad hoses

I'll check it out. 95C is pretty hot, IMHO.

[digger]

Thanks for the responses, guys. I do have a temp gun. What temp should I be looking for?

I spoke to AutohausAZ. They don't like the rolled newspaper test. He said with the car at operating temp, shut it down and turn the fan by hand. It should not go more than 1/4 to 1/2 a turn. Mine goes 1/2 a turn.

Still looking for good confirmation that my new fan clutch is working correctly. It's interesting to me that it locks up (turns super fast) upon start up, then loosens up.

turn engine off and point at the fan hub to see what temp the alloy housing is. if its at 95C it should be working. also check the themostat housing and rad hoses

[whodwho]

Their spin test 'at temp' is not necessarily a good test.

'at temp' the fan is not needed, above temp is when it is needed. Depending if the clutch is engaged you can easily spin the fan freely backwards to engine rotation and the motor is idling warmed up.

From your post it sounds like it is working, you can also hear it moving air when it is engaged. Some temp swing is normal, I wouldn't stress if it is not overheating idling. I would just make sure it is bled fully they are very sensitive to that.