kastmaster Posted June 22, 2007 Share Posted June 22, 2007 I have now come to the next thing on my list for completely eliminating this overheating problem on my 280zx. The problem as of now: It will sometimes overheat (meaning not consistantly) at a stand still ONLY when the AC is being used. It will not always overheat when the AC is being used, but that is when it is more common. My take on it: I am now looking at the fan clutch (it's original, has 107K miles on it) since i'm trying to go "down the list" of typical overheating problems. IS THIS TEST FOR THE FAN CLUTCH TRUE? (Taken from zhome.com): "If you want to test your fan clutch, it is not even necessary to remove it. While the car is cold, and turned off, try and turn the fan. It should turn easily. Then start warming up your car. As you stop the engine and test the fan, it should get progressively harder and harder to turn freely. It will never lock up completely, but you can tell that the clutch is working." Quote taken from this website: http://zhome.com/ZCMnL/tech/280ZXCool.html Before pulling the fan clutch, i wanted to know if any of you know that the above quote is true. If so, then I can clearly test the fan clutch and determine if it is my problem for overheating like through a drive through where it's really stop and go. It overheated with the AC on while waiting in a Taco Bell drive through. After a minute of driving back on road, it went back to normal but then my coolant reservior tank was empty Let me know if u guys need a brief history as to what is done to it so far. -------------------------------------------------------- Also, do you guys think that if my car is running too rich (which it is) that that could contribute (either big or small) to overheating? I do not know of any temperature-wise effects (if any) caused by running rich. I failed my smog test Running too ruch, like 4 times over the max line. I think max was 1.35, my reading of CO was like 4.32 lol. PREVIOUS WORK DONE TO FIX OVERHEATING PROBLEM:New coolant hoses, flushed radiator it's only 2 years old MAX), New 13Psi rad cap, new water pump (6 mo. old)., new 180*F Tstat, 50/50 coolant mix..... More info gladly given if needed Quote Link to comment Share on other sites More sharing options...
Hartspank Posted June 23, 2007 Share Posted June 23, 2007 I'm not a master tech by any means but... I added an electric fan to my zx and just spliced the power wire for the fan relay to the positive wire on the a/c pump, so when you switch the air on, the fan comes on also. Seems to keep things cool. Quote Link to comment Share on other sites More sharing options...
spacecase70 Posted June 23, 2007 Share Posted June 23, 2007 the answer is true, if you try to spin the fan when cold, it should spin abot two times and stop. when warm it shoudl spin hard. also dont forget to change you hoses they could be collapsing, which causes restriction of the flow. as for you rsmog issues, If your running rich your air flow meter may be off a tooth or two, and there is a rubber plug on the left side of the afm that uses a screw to adjust the A/F ratio. you may have it running too rich there. running lean can cause overheating and you dont seem to have that problem. but i personally would put a new fanclutch on it my self Quote Link to comment Share on other sites More sharing options...
Daeron Posted June 24, 2007 Share Posted June 24, 2007 the answer is true, if you try to spin the fan when cold, it should spin abot two times and stop. when warm it shoudl spin hard. also dont forget to change you hoses they could be collapsing, which causes restriction of the flow. as for you rsmog issues, If your running rich your air flow meter may be off a tooth or two, and there is a rubber plug on the left side of the afm that uses a screw to adjust the A/F ratio. you may have it running too rich there. running lean can cause overheating and you dont seem to have that problem. but i personally would put a new fanclutch on it my self the only way for the AFM to be "off a tooth or two" is intentional fiddling by a PO; and the "A/F ratio adjustment" you mentioned is the idle air adjustment, which controls how much air bypasses the throttle plate to supply the engine at idle. If the AFM is mis-calibrated, then it may need to be tuned in.. but they usually dont "go off" from normal use. Aclibration directions should be available in Blue's techtips page, http://www.atlanticz.ca/zclub/techtips/EFI&fuel.htm Sorry to correct you, I don't mean to sound like an ass. Quote Link to comment Share on other sites More sharing options...
kastmaster Posted June 24, 2007 Author Share Posted June 24, 2007 Hey guys, I really appreciate ALL of your feedback. Lots of knowledgable people here! I tested my fan clutch, and it spun the same distance when it was off and hot, as well as off and cold. Hmm.... I read somewhere else that there is oil inside it? Possibly for lubrication? And that I read that that oil in the fan clutch gets cruddy causing for not a "smooth" engaging fan clutch. This fan clutch is 27 years old. Daeron, yes that's what I was thinking too, that it was reference to the idle speed adjuster. It is set to idle at 800 when cold, and once it warms up to ideal temp (gauge in middle or so) it idles at 950 or 1000. Spacecase70, all coolant hoses have been changed, but next time (if ever) it overheats on me again at stops, I will definitely check the hoses out again. Do hoses tend to collapse when hot or cold? (sorry, noob question ) Again, thanks for your guys's time and effort. Quote Link to comment Share on other sites More sharing options...
kastmaster Posted June 24, 2007 Author Share Posted June 24, 2007 I'm not a master tech by any means but... I added an electric fan to my zx and just spliced the power wire for the fan relay to the positive wire on the a/c pump, so when you switch the air on, the fan comes on also. Seems to keep things cool. Not a bad idea, if worst comes to worst, I may have to do that same thing. Do you notice any negative effects as far as electrical goes? Dimmer headlights, dimmer anything? Or is it not that much of a current that it draws? Thanks again. Quote Link to comment Share on other sites More sharing options...
Daeron Posted June 24, 2007 Share Posted June 24, 2007 A fan like that will draw plenty of current.. but there ARE alternator upgrades available, if you are willing to do some minor custom re-wiring. Most of the stock wiring on these cars is so bad at this point, that alot of it should be reconstructed anyhow. If your fan clutch spun freely when hot, then it is not engaging when hot and your fan isnt spinning. It sounds like you need a new clutch. Quote Link to comment Share on other sites More sharing options...
spacecase70 Posted June 25, 2007 Share Posted June 25, 2007 the hoses will collapse at any temp according to my experiance if they are old and need to be replaced you should also squeeze them periodically to make sure they are supple and not soft or hard Quote Link to comment Share on other sites More sharing options...
kastmaster Posted June 25, 2007 Author Share Posted June 25, 2007 I'm going to be ordering a new fan clutch soon. I will post back here with results so others with same problem will benefit. Daeron, thanks for your reply. The temp gauge crept up on me again (about 3/4 to the double line) And all I was doing was sitting at idle for not even 3 minutes with AC on Definitely feeling that the fan clutch is crapping out. I will still double check those hoses, although they're new. Ya never know. Thanks guys, my first thread, been a lurker though haha. take care. Quote Link to comment Share on other sites More sharing options...
X64v Posted June 28, 2007 Share Posted June 28, 2007 A little bit of misinformation above... The fan will spin an infinite number of turns in either direction, no matter it's temperature. There is no solid mechanical link between the fan and belt. The fluid in there makes a viscous connection, very similar to a torque convertor. It will never lock up, regardless of temperature. It should just be easier to spin while cold, and harder to spin while hot (there is a wound metal spring on the front of it, similar to an electric choke or a cheap outdoor dial thermometor. It expands as it warms up, turning a valve inside the fan clutch, which makes it harder to turn). If it takes the same effort to turn cold and hot, then that spring is broken/missing or there is another problem with it, and it needs to be replaced. As to slapping on an electric fan to cure a cooling issue, it's not going to help...see link below, page 5. The stock fan is adaquate, provided it's working correctly. http://www.grapeaperacing.com/GrapeApeRacing/tech/coolingsystems.pdf Quote Link to comment Share on other sites More sharing options...
kastmaster Posted June 28, 2007 Author Share Posted June 28, 2007 Ordered the fan clutch. It's on its way. Had a question. I live in the Central valley of California, Fresno to be exact. It can commonly reach above 100* F here for weeks straight. Am I better off going with, let's say, a 70/30 mix of water/antifreeze, respectively? Compared to 50/50? The car is garaged all year round, so freezing is not really a problem. I was asking about the 70/30 so i can have a more effecient cooling mix. Let me know if this sounds okay, even if the difference in mix is slight. Thank you! Quote Link to comment Share on other sites More sharing options...
kastmaster Posted June 28, 2007 Author Share Posted June 28, 2007 A little bit of misinformation above... The fan will spin an infinite number of turns in either direction, no matter it's temperature. There is no solid mechanical link between the fan and belt. The fluid in there makes a viscous connection, very similar to a torque convertor. It will never lock up, regardless of temperature. It should just be easier to spin while cold, and harder to spin while hot (there is a wound metal spring on the front of it, similar to an electric choke or a cheap outdoor dial thermometor. It expands as it warms up, turning a valve inside the fan clutch, which makes it harder to turn). If it takes the same effort to turn cold and hot, then that spring is broken/missing or there is another problem with it, and it needs to be replaced. As to slapping on an electric fan to cure a cooling issue, it's not going to help...see link below, page 5. The stock fan is adaquate, provided it's working correctly. http://www.grapeaperacing.com/GrapeApeRacing/tech/coolingsystems.pdf Thank you, I really appreciate the verification It indeed does spin the exact same with the same amount of effort. It doesn't even spin one full turn when cold. It just feels like it's jammed, or sticky when I try to spin it. No smoothness when turning it while cold at all. Quote Link to comment Share on other sites More sharing options...
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