Holy ****. You didn't say that. Not Really, it's a joke right? Have a mod delete this, please.


Wait, you are a Mod, right?

 

The fan clutch is self checking. Is the car cooling? Yep! Fan clutch is working. Does it freewheel? Yep! Clutch is working. If one of those conditions is met then it has failed.

I do hope that people won't take my joke seriously. One should never jam their fingers into an unknown clutch fan without first making sure the clutch isn't seized by turning the fan while the engine isn't running. Then if they really want to stop it while running, an inanimate carbon rod or some other implement is preferred to a finger.

 

You heard that from me.


There is nothing special about Mazda's implementation of the thermal clutch. It is a mechanical controlled thermostat on a hydraulic coupling. So since we cannot get technical details from Mazda, how bout we go to one of the largest manufacturer's of replacement and oem fan clutches in the world?

Hayden sells three different levels of thermostatically controlled thermoclutches:
Standard Duty, Heavy Duty and Severe Duty. The main difference in the three clutches is the percentage of fan speed vs. shaft speed at which the fan runs when clutch is engaged and AND DISENGAGED.

On page 2 of the spec sheet, Hayden shares that even 'disengaged' the clutch (and therefor the fan) is still turning at a specified percentage of the shaft speed.

Specs below, stated in fan speed in percentage of shaft speed:

Standard Duty: Disengaged=20-30% Engaged=60-70%
Heavy Duty: Disengaged=25-35% Engaged=70-90%
Severe Duty: Disengaged=20-30% Engaged=80-90%

http://www.haydenauto.com/upload/Hay...n-clutches.pdf

So-the thermo-fan clutch NEVER completely disengages, nor does it ever completely lock up.

To wit: at 3500 rpm highway speed, the fan is being turned at at least 700 rpm and maybe as much as 1225 rpm IF the fan is completely 'disengaged'. If it is not 'completely disengaged' it is turning the fan faster.

Given that some folks consider a running e-fan to be a restriction, should you also consider the mechanical fan running at highway speeds a restriction?



BTW, Many modern thermo clutch fans have added a electro-magnetic clutch similar to an A/C clutch to permit true freewheeling. My Toyota Tundra worked that way.

 

I wouldn't stick any object into the fan on a running engine. I have a mental picture:

 

Put a lime in de coconut and call me in the morning....

 

Hmm..I see you found a pic of the last guy who asked if he should run Regular oil or synthetic..lol!

 

These efan threads are a real headache...

 

agreed.

 

That "exclusion" method of diagnosis (i.e., "The car is cooling properly ergo the fan clutch is fine") only works if the thermoclutch is the sole part in the system, which it obviously is not.

If you're allowed to say that normal cooling proves the fan clutch is good, what happens when the cooling is abnormal...does that prove it bad?

 

the technique is important, you don't just jam your hand in there like a stick in the spokes of a motorcycle wheel. you have your hand almost flat to the fan, and since the fan is basically freewheeling, stopping the thing is much less drama than you would think.

you should try it some time.

gloves are not even needed, although its not a bad idea. using a rag is a bad idea, too much stuff to get caught

 

the specs on the FC fan are in the training manual, Foxed.ca - Mazda RX-7 Manuals

 

I guess that's where the experience and intuition of troubleshooting comes in. I've always been able to diagnose a clutch fan by feel. Guess that doesn't help anyone much because you can't transfer "feel".

But it's part of standard cooling troubleshooting.

If it overheats at low speed and idle, but maintains cooling at high speeds, then it's a fan issue. Thus, check the clutch. If the thing still freewheels when the car is overheating (shut the engine off and try to turn the fan) then you've found the issue.

 

So the training manual says at 3200 rpm the fan is turning +/- 86% at max and 24% at minimum engagement. That would be 800 rpm and 2750 rpm.

Pretty closely correlates to my numbers derived from the tech sheet a Hayden.

Thanks for the training manual suggestion. I have them on my backup drive, but haven't consulted them for years. I had pretty much had forgotten about them.

 

I'm not saying it can't be done. I'm just saying that it shouldn't be done, especially when suggested on a public forum to an audience containing one or more dumbasses.

I don't have to do some things personally to know it's a bad idea. For example, I knew an old man down at the Napa store who could grab a spark plug wire then spark his dick onto the fender of the car. I was in high school and pretty cocky. The old man had bet me that he could do something that I wasn't man enough to do. I lost $5 on that one.

True story.

 

I'm trying to imagine the scenario where he first discovered this talent.
"One giant leap for mankind" and all that.

 

Wondering if he actually whipped his dick out and tapped it to the fender. If that's the case, the $5 would be the last of my worries.

That napa sounds a little wild. What with old men sparkin' dicks and all.

 

that's just it, stopping the fan and sparking your wedding tackle, are nowhere near the same danger level. sparking dick sounds dangerous, spotted dick is food.

putting your finger in the fan, is less dangerous that walking on a carpet with socks on (static charge). the stock fan isn't really coupled to the engine, and has almost no inertia, it stops easily. if you want a challenge stop the house fan with your finger, THAT has power, if you want the napa guy challenge stop the house fan with your bits.

so just to recap, if there is a fan i will stop it bare handed. you will pay someone $5 to use their gentleman's sausage as a sparkler. i think we are both right.