Fan Clutch Emergency!!!

[Julio Bro!]

I have a 1993 240SX SE, about a week ago the temperature suddenly began to go up. Since new the car never gets past the 3rd line if everything's fine, during this week it was between the 4th and 5th lines.

Since there are no leaks and the pump seems to be working OK, I checked the workings of the mechanical fan. With the engine hot I switched off while looking at the fan, and it kept on turning quite a bit. So I bought a replacement fan clutch ($40) Shimahide brand and numbered 21082-40F00 (supposedly the correct part number) and installed it. Incredibly the car heated more, now I was getting almost past the 5th line; I observed the same functioning so I thought I got the lemon part. I was mad and very worried.

I got my money back and bought one from another shop, this one is ACE brand and numbered D21082-01P04 ($55 replacement for 300ZX and 200SX but identical to the 240SX model), installed it today and it's behaving just like the "damaged original"; although I see the same "flaw", now I'm worried if it's something else...what are the odds of a second lemon?

Are these bad brands...could it be something else? Please suggest an online shop for the correct and reliable part.

Thanks in advance.

[navysnail]

is it cooling down at idle or heating up

when you start driving does it cool back down or heat up

if it cools when your driving and heats when you stop, then its the clutch, if its always hot, then its your radiator or thermostat.

[Julio Bro!]

Hi 240kid:

When driving it keeps hot...although when going downhill in 5th gear, temperature tends to drop, but not enough because traffic's been heavy these days. But what about the fact that the fan keeps turning a lot when engine's off?

Also I noticed the electric fan keeps on during these temperatures...could this make matters worse?

I've been looking at some fan clutches online and most go for $130...could this mean I'm getting a piece of crap?

[navysnail]

electirc fan comes on when the ac is on or when the coolant is over 212. i got mine for 80 when it locked up. if it stays hot when driving, then its probobly not the fan clutch as the fan only helps cool things down when the car is not moving. if i were you, id flush your radiator, change the coolant and thermostat, and make sure to completely bleed the system via the bleed hole on the intake manifold.

[Julio Bro!]

OK 240kid, I'll give that a try and tell what happened.

Is it difficult to change the thermostat; any particular way of flushing the system?

I have the factory service manual and has a very detailed flush procedure. Is it really necessary to open the drain plug at the cylinder block?

Oh, I also noticed that the A/C won't work at the high temperatures either, the compressor doesn't engage.

[navysnail]

the a/c generates heat. what most dont understand is that ac doesnt necessarily cool you, it just moves the heat to another location, that hapens to be the evaporator in front of the radiator. if its hot, it cuts the ac so hot air isnt blowing into the radiator.

opening the drain plug on the block is helpfull, just to get the old coolant out. make sure you take the old coolant to a toxic waste disposal site.

the thermostadt isnt too hard to install, just make sure you put it in the same way as the old one, and i think there is a small hole in the top to allow air to get out.

to do coolant, just drain it, fill the radiator up with fresh water, then run it for a little while, then drain it and fill it up with 50/50 coolant and distilled water.

[Julio Bro!]

Thanks 240kid; I'll leave an hour early today to buy the thermostat and 2 gallons of mixed coolant. If it isn't much of a problem, I'll open the block's plug, if it's too much I'll try my best with the rest of the system.

I'm curious about why you have to switch the A/C to hot, what is the purpose of this step?

PSI noticed the electric fan is controlled by the computer and works by itself even if the A/C is OFF. Could it be a good idea to replace the whole setup with a 2 fan system, or 1 big fan, and just plug it to the electric fan circuit?

Another possibility with a 2 fan system could be, plugging one to the electric fan connection and the other make it dependent on something more performance oriented, like speed or throttle possition. Has any of this been done?

[navysnail]

well, fans do nothing for cooling when the car is moving. some people do swap an electrical fan inplace of the clutch fan. the electrical fan wiill come on when the temperature of the coolant reaches 212 as well as when the ac is on.

you put the heater on all the way so that the heater core will open up and allow the coolant to drain out of it as well.

when i flushed my coolant, i didnt open my block plug and it worked fine, just opening the block plug makes it a hole lot easier to flush it. make sure the coolant you pour in is green, if its red, it may cause engine damage by gumming up the cooling system.

hope that helps, if you have any questions, just ask

[ricebike]

make sure the coolant you pour in is green, if its red, it may cause engine damage by gumming up the cooling system.

hmm, do u have links to this? i'm using dexcool/distilled water for the past 6 years w/out any problems... of course, i completely flushed out the green fluid 3x before using it...

maybe mixing the 2 will cause it to "gum up" the system, but i never heard or read anything about it.

thanx

[Julio Bro!]

[QUOTE]Originally posted by 240kid "]well, fans do nothing for cooling when the car is moving. some people do swap an electrical fan inplace of the clutch fan. the electrical fan wiill come on when the temperature of the coolant reaches 212 as well as when the ac is on.

So the new fans could be used with the existing electric fan connection? What about a setup using speed as the trigger factor?

On my problem, yesterday I couldn't find the thermostat, today I know where to get it so the job is this afternoon.

[Asia989]

try this, do away with the fan clutch, itll free some hp and give u more room, get two 12" electric fans and itll solve ur problem, the shop where i got mine done at wired it so when i trun the key they come on and stay on

[navysnail]

a speed setup would be very hard to wire and it would also not work because the fans only pull air slowly, when your going even 25mph, the fans do nothing

[Julio Bro!]

Alright, yesterday I was able to remove the thermostat...looked old...it figures, since 1993. Also the fluid had somekind of brownish crap, didn't look like rust though. Maybe I add something for leaks or other stuff at sometime and those are the results. Anyway I flushed the system and install the new thermostat.

Got a bit of a scare, at no load I couldn't get the temperature to rise much, so I just went and would stop to fill more mix when temperature rised. God! it went up too fast, I had to turn off the engine and roll to a nearby gas station. There I completely filled the radiator system, man that was close, and at 9:30pm.

I suppose next time I'll have to give it a little run in the street and go back to complete the work...although I don't expect to do this again for at least 5 years.

What I got from all this is if your old model got the electric fan damaged...go ahead and change also the thermostat, fan clutch and pump (if not already replaced). Just taking advantage of what you have to dismount and you'll be good for 5 years or more.

Thanks for your help 240kid.

PS

When suggested speed controlled it should be like turning OFF once the car goes for more than 12 mph. I ask again, could the system be connected directly to the electric fan plug?

[navysnail]

ahh, i thought you meant it to come on, yes you could hook it up like that but i dont know how you will make it automaticaly come on and off when the speed got above a certain value.

so its not overheating anymore, thats great, glad to hear that

[Julio Bro!]

Well, it could be using the speed signal from the sensors, the same one feeding the computer. I suppose it gives a rising voltage as speed goes up, with an electronic switch, or relay, set to a given voltage the signal for the fan relay could be obtained.

But 240kid you haven't said if the aftermarket fan system could be just plugged into the existing fan connection. Anyone has tried that?

[navysnail]

yes it can be pluged in

the sensor uses pullses and the pulses increase the faster you go so i dont think that would work

[p00t]

brown coolant? definately bad stuff!!!

make sure you installed the thermo right, and that you have between 30-50% antifreeze to water ratio. antifreeze is a poor conductor of heat... the less the better. water is great on the other hand but will freeze/boil quicker by itself (thus the need for the necessary evil...aka antifreeze)

Now you need to fill the coolant correctly, new coolant is good but by draining it air is all over the place in the system. with the car cool: you need to jack the front of the car up a good amount....20-30 degree angle if possible. then open the rad cap, then the bleeder bolt on the intake manifold (it will say do not open when hot and is a small 10mm bolt). Just trace the upper rad hose to the intake mani and you will find it!

Water needs to come out of that bleeder hole, then you close it and tighten it GENTLY. then fill the rad up 1/2" from the brim, start the car let the air work its way out.... after 30seconds stop the car and refill if nessisary, close the rad cap and off you go... problems will hopefully be solved!

also squeezing the upper rad hose with the car tilted up will help get some air out... but not much.