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Discussion Starter #1
Hey!

I'm having some overheating problems and I'm thinking my fan clutch may be bad. What's a good way to test it?

If I stop at a red light for too long I notice the engine starts to overheat. If I turn the heat on the temp usually goes down right away. I usually don't overheat while driving, unless I'm doing 100km or more. Any suggestions?

- Mike
 

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The best way I found is to stick a whisk broom in there when the engine is warm. There should be some resistance, but you should not be able to stop it. I had to change the fan clutch in my '80 Celica because it was so bad I could stop it with my finger (NOT RECOMENDED).
 

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I doubt its your clutch fan, but most of the ones out there that are 15+ years old don't lock up as they should. If you never hear it locking up, then its probably beat, but only under the hottest weather or most extreme stress would that cause your car to actually overheat. Check your heater core valve man, any leak in your system will give you the symptoms you have. Check for leaks everywhere. Some leaks don't open up unless the engine is running and really hot. Thats generally the case with the valves. You had coolant depoists on yours.
 

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It could be that your thermostat is stuck shut, thats what was wrong with mine.

HTH's laterz

zank
 

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Discussion Starter #5
Okay, well, as I suspected, my fan clutch is bad. Even with the engine warmed up and running I can stop it easily with my finger. In fact I can even spin it backwards with ease and it takes a few seconds before it slows down and slowly starts spinning in the right direction again. I swapped it with one from the junkyard and it does exactly the same thing (now I have to take it back and try to get my money back!).

Seamus, you're probably right. I keep checking for coolant leaks there and haven't found any yet. Those deposists are all green and I'm running the red stuff now, which doesn't seem to leave very noticable deposists. The reason I'm doubtful of the heater core valve being the problem is because I had some hoses burst in that area and I have green deposts all over the place. Anyway, I may end up doing a pressure test on the system. I'll also look into getting heater core valve replacement (I'll check to see if that 85 parts car we have I told about still has that valve intact).

As for the thermostat... It's only about a month or so old now, I bought one from Canadian Tire before I drove out to Vancouver (it opens at 82C, 180F). I pulled it out just an hour ago. It looked good. I threw it into some hot water (not yet boiling, but just on the verge) and it opened up nice and quick. Then threw it into some cold water and it closed up right away. The upper hose builds up pressure in proportion to my temp guage so I'm thinking it's probably not the t-stat.

One question... I'm using an aftermarket rad cap. Could that cause problems? What's the recommended pressure rating for the rad cap?

- Mike
 

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thermostat problems are easy to diagnose. If the car warms up to the normal level after about 5 minutes of idling or light driving, your thermostat is fine. Its too low or too high the spring is shot on the thermostat.
 

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just bypass the heater core valve before you replace it. You should be able to stop your clutch fan with your finger. But it should lock up after the car starts to get a little hot. Get someone to watch the temp guage and if the needle goes into the red and the clutch fan doesn't lock up its foobared. But like I said, most of the original clutch fans out there are. The clutch fan is pretty much a band aid solution. They should only lock up in really hot weather or if the car is over heating. If you still need a fan I migh sell you mine. I bought a brand new hayden one last year and it works pretty decent, but I'm going to install my electric fan soon. Your clutch fan isn't your problem though.

Let me know if bypassing the valve doesn't fix it.
 

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Discussion Starter #9
How old is the water pump?
Good question! I really don't know, and I suppose that could also be the problem.

Seamus, I cleaned off my heater core valve, which will make it easier for me to spot any new deposists. I also pulled off the valve of an 85 parts car, but that too seems to have deposists on it. Bypassing the valve would probably be the best option for now.

I haven't had any overheating in the past two days as the weather has turned cool and rainy, and I only overheated when the temp was pretty warm. It's possible I won't overheat again until next year, so I may just put this on the back burner until then. I will however keep an eye on my temp guage and always on the look out for leaks.

- Mike
 

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I know its alittle challenging in the praries, but try and find a steep hill and floor it up that. That would always get it going when my cars were overheating. Bypassing the valve first is the best thing to do. That way you save your money if thats not it, and its more conclusive too because most of the used valves in wrecking yards seem to have the depoists too.
 

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Discussion Starter #11
I know its alittle challenging in the praries, but try and find a steep hill and floor it up that. That would always get it going when my cars were overheating.
Well, I managed to get it to overheat, even with the cooler weather. I just drove it really hard for 20 minutes and sure enough the guage went above center (and I tested the fan clutch again - total failure). The odd thing is my digital guage always goes from dead center (normal temp) to +2 above center - never +1. Kinda weird that it would jump a notch on the digital scale. It does this when it overheats and when it cools down it jumps back down 2 notches.

Anyway, today I was working on the engine and I noticed something interesting. I started the car up in the morning and after the engine warmed up I noticed some white smoke comming up between the power steering pump and the exhaust cam. At the time I assumed that I have a crack in my exhaust manifold somewhere, but now that I think of it, it's quite possible that there's a coolant leak in the area. Possibly the lower rad hose where it connects with the engine (although upon inspection it seems fine) or the water pump itself. What may have happened is that as the car cooled off over night some coolant leaked out. When I started it up the leaked coolant started to steam, which would explain that "white smoke" I saw. However, the leak must be pretty tiny as I can't see any steam (or smoke) rising after driving the car around. Anyway, I'll start the car up again tomorrow morning and watch for steam to rise from the same spot. If I see steam rising again that could explain my overheating problems!

And btw, I cleaned the heater core valve with sand paper, so the copper is nice and shinny. If it leaks I'll know about it right away, and so far it's still pretty clean, even after I overheated the engine.

Oh, and to exclude the possibility of a BHG, I checked my plugs for residue and found nothing but some carbon buildup. My tail pipe has only black residue and I don't see white smoke once it's warmed up. My coolant is oil free and my oil is black. I may be running rich or my timing could be off (it idle's a bit on the rough side), and that too could cause over heating, but could it be this bad?

- Mike
 

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If you want to keep your temp low you can split the fan clutch housing. There should be some bolt and if you take them out it will come of. Then you can either use old piston ring or similar washer or something and put it back together. It will rev with the engine and it gives a loud fan sound. Sounds like a plane. We did it to most of the mark2,chasers and stuff. It really keeps the engine cool in those tropic countries.

Just a thought. It takes alittle bit of engine power though.
 

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a little? It makes your car sound like a bloody hovercraft and sucks the life out of it! I would seriously not recomend that, I tried it myself once and immeditaly took it off after I started it up a bit and reved it. Can't be good for gas milage, power, water pump bearing life etc etc. Might be ok for a v8 with a 5000rpm redline but not on modern dohc engine.
 

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Discussion Starter #14
Hey, this got me thinking... is there a way to refurb the fan clutch? All it would need is to replenish the fluid inside and perhaps change a gasket, no? Are there refurb kits for these?

- Mike
 

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When mine locked up it was bad. At 5000rpm, it was in fact a bloody hovercraft. As for sucking the life out of it, that does it no justice. You can not accelerate. Period. Dont do this.
 

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Actually, if your tranny, diff or axels ever break and you need to continue driving your car, a good trick is to bind your clutch fan so it will be fully engaged 100 percent of the time. Then put it into neutral and rev it to over 5000rpm. That little fan will actually provide enough suction to generate enough forward motion to get you home. Try and steer clear of debris, small animals and children, they may be sucked into your condensor :wink:



:lol:
 
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