2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

What are reasons to run hot?

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Old Jul 14, 2007 | 05:15 AM
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Mankdrake 2661's Avatar
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From: Collinsville, IL
What are reasons to run hot?

I'm running tooooo hot! Ever since I put this n/a block in I've had cooling problems. I've never overheated this motor but maybe someone before me did.

I've fushed the cooling system twice, replced radiator caps, Im running the 50/50 mix of coolant, all stock duct work is there, I've got a koyo radiator, replaced the thermostat. My next guess is the water pump.

Any more ideas? I've still got the original motor so I know that that water pump is good. I'm going to put that on on and see what happens.
How can you test the fan clutch?
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Old Jul 14, 2007 | 06:47 AM
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From: Sanford, NC
Originally Posted by Mankdrake 2661
I'm running tooooo hot! Ever since I put this n/a block in I've had cooling problems. I've never overheated this motor but maybe someone before me did.

I've fushed the cooling system twice, replced radiator caps, Im running the 50/50 mix of coolant, all stock duct work is there, I've got a koyo radiator, replaced the thermostat. My next guess is the water pump.

Any more ideas? I've still got the original motor so I know that that water pump is good. I'm going to put that on on and see what happens.
How can you test the fan clutch?
Based off of your symptoms, I'd definitely say a bad water pump. While I don't have a Koyo radiator, everything else was the same in the situation.
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Old Jul 14, 2007 | 07:06 AM
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Originally Posted by Mankdrake 2661
How can you test the fan clutch?
The non-technical, poor man's test...
When cold (engine off), spin the fan.
You'll feel a bit of resistance but not much.
Warm up car (hood closed) till temp gauge reads normal then spin fan again.
Should feel noticable amount of resistance.
Originally Posted by Mazdatrix
These go bad in two ways - either seized-up, which is very hard on the water pump and belts (and very noisy), or they are free-wheeling, which gives overheating while stopped or slow driving. With the engine off, there should be no side-to-side play, and reasonable resistance should be felt when you spin the fan blades. We have seen a few that were very inconsistent - they would feel fine for four or five spins, then go completely free-wheeling, and/or seize up. The later (84+) fan clutches have thermostats in them that vary the resistance of the clutch according to the temperature of the air moving across them.
In my (limited) experience with these things, the hub tends to lock in full engaged mode...this is inefficient but at least the fan works. Last trip through the junkyard all the suitable clutches had no freewheel at all.
The clutch on my car did just the opposite and freewheeled even when hot.
Too bad new replacements are soo pricey.
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Old Jul 14, 2007 | 09:18 AM
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Here you go: http://aaroncake.net/RX-7/cooling.htm

Also, from my experience they usually fail in the freewheeling mode. Both of mine have done that.
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Old Jul 14, 2007 | 09:28 AM
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You can also catch a bad fan clutch if your problems go away at freeway speeds (when you don't need a fan). But also do the test mentioned above. If your fan clutch is bad, an e-fan might be cheaper than a new one. That's the only reason to replace the stock fan, btw. It'll put a big load on your small alternator though.

The FAQ or a search will tell you how to check for a bad coolant seal.

Make sure your thermostat is OEM.
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Old Jul 14, 2007 | 09:58 AM
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The fan is connected to the water pump.
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Old Jul 14, 2007 | 09:58 AM
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How hot is it running? You are within safe temperatures if you are under 230 F

You probably need to run a lower mix of coolant and water, unless your area freezes up in the winter, in which case you are fine.
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Old Jul 14, 2007 | 11:14 AM
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i had the same problem, but i had a black magic fan installed previously. i thought it was the water pump, but was wrong. just install a taurus fan.. i can keep my engine at any temp i want with my taurus fan. bottoms at 84 in 90+degrees. i say thats good for a turbo car..
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Old Jul 14, 2007 | 12:18 PM
  #9  
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From: Collinsville, IL
Thanks everyone. According to the aaron cake page I probly have a clogged radiator. I'm goint to start there. I wouldn't be suprised if it was. Thge block I'm using had been sitting for a couple years empty of water.

But yeah thanks for the help.
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