XPLORx4 Posted March 7, 2017 Share Posted March 7, 2017 First, the temp gauge reads middle from about 160-220°, so you cannot rely on it for precise temperature readings. You will probably need to find the turn-on temperature without driving. Start the engine when cold and just let it idle until it warms up. Do not open the hood. Watch the ECT (Scan-gauge?) and determine when the fans turn on. You may need to reposition the location of the sensor. On the VQ35, does hot coolant enter the top and exit the bottom of the radiator, or is it the other way around? (VG33E coolant flows from top to bottom.) Link to comment Share on other sites More sharing options...
Mbrianc Posted March 7, 2017 Author Share Posted March 7, 2017 (edited) I have done that multiple times from cold. The ECT reads 190 the first time the fans run. 192 after it is warmed up. The radiator is a top down flow. The sensor is installed about two inches below the coolant inlet. All of the testing I have done with it I have been using my scan tool. With the hood open, ECT goes from 190-192 back down to 189 when the fans cycle. When the hood is closed, the ECT doesn't change at idle. No increase or decrease at idle and the fans are constantly on. At speed, the temps go as low as 186 and of course the fans don't turn on. Edited March 7, 2017 by Mbrianc Link to comment Share on other sites More sharing options...
Mbrianc Posted March 7, 2017 Author Share Posted March 7, 2017 My scan tool is a Bluetooth OBD dongle combined with the NDS II app on my phone. I can even log data while I drive and reset self learning and learn idle air volume with it. Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 7, 2017 Share Posted March 7, 2017 What happens if you set the fans to come on at a higher temp (eg 195°)? Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 7, 2017 Share Posted March 7, 2017 I suspect there is more back pressure in the engine bay when the fans are on with the hood closed and fans become less efficient at drawing air through the radiator. If you want to get super geeky about this, you could buy one of these: http://www.homedepot.com/p/General-Tools-Mini-Digital-Airflow-Meter-DAF800/202074524?cm_mmc=Shopping%7CTHD%7CG%7C0%7CG-BASE-PLA-D25T-HandTools%7C&gclid=CjwKEAiA0fnFBRC6g8rgmICvrw0SJADx1_zAO1JGPfWpUv2kEdDALDAjNkl7Vg2YfkYAAAiaFtnMwRoCBtXw_wcB&gclsrc=aw.ds Link to comment Share on other sites More sharing options...
Mbrianc Posted March 7, 2017 Author Share Posted March 7, 2017 Same thing. Hood open, the temp drops a couple of degrees and the fans turn off. Hood closed, the temp doesn't change and the fans stay on constantly once the temp is reached. I'll also note that the controller doesn't have the temp in increments on the screw. I don't know what temp the controller thinks it is set for, which is why I am using the ECT. Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 7, 2017 Share Posted March 7, 2017 So, whenever the hood is closed, if you set the fans to come on at a much higher temp (e.g 210), do they fail to reduce the coolant temperature? If that's so, then I am very suspicious that the back pressure is definitely affecting the fans' efficiency and ability to exhaust the hot air. Link to comment Share on other sites More sharing options...
Mbrianc Posted March 7, 2017 Author Share Posted March 7, 2017 I haven't tried a temp as high as 210. I tried 195 and 200. If it worked at 210, I am not sure I would be comfortable running it that high. I did a test with the the heater on max and the ECT went all the way down to 175! But the fans still didn't shut off with the hood closed. Really has me scratching my head. Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 7, 2017 Share Posted March 7, 2017 Do you have a pic of the installation? It could have a lot to do with the way the fans are shrouded. Inadequately shrouded fans not only fail to pull air through the entire radiator, but they can also exhaust hot air back through the radiator instead of behind/below the engine bay, especially if there is a lot of back pressure. Link to comment Share on other sites More sharing options...
Mbrianc Posted March 7, 2017 Author Share Posted March 7, 2017 I can get you one in a few hours when I am back at the house. If it is a shroud issue, I have a maxima fan shroud without the fans. A little work with some scrap sheet metal would fit my fans to it. Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 7, 2017 Share Posted March 7, 2017 One last comment: note that the temperature probe (if you have it inserted in the metal cooling fins of the radiator) is not going to be measuring the coolant temperature. It measures the temperature of the metal fins adjacent to its location. Coolant flows from the top tank of the radiator through each of the vertical coolant passages to the bottom tank. Now, let's say you run an experiment where you place a fan that blows freezing cold air on 1/2 of the radiator and nothing on the other half. And now, let's modify the air flow so that air drawn through the radiator is forced to exhaust back through the other half of the radiator. If you place you temp probe on the half of the radiator covered by the fan, it will measure a different temperature than if you place it on the other half, neither of which will be close to the actual coolant temp. That being said, when I had a Flex-a-lite electric fan installed, its temperature probe actually inserted into the upper radiator hose, measuring the actual coolant temperature, not the radiator cooling fins. The location of the probe may be another source of the problem. Link to comment Share on other sites More sharing options...
Mbrianc Posted March 7, 2017 Author Share Posted March 7, 2017 I'll send a pic in a little while but I think you are correct. While those fans were rated at 1650 and 1200 cfm, I would bet there performance is reduced when encountering that high pressure air pocket created by a closed hood. And yes perhaps even forcing air back through the radiator. Out of curiosity, your problems with electric fans developed while offroading and using extra light bars and such correct? No problems under normal driving conditions? Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 8, 2017 Share Posted March 8, 2017 your problems with electric fans developed while offroading and using extra light bars and such correct? No problems under normal driving conditions? Under "normal" driving conditions, the fans worked, but in the summer (100°F+), when climbing long grades or idling, engine temps would go up to about 216° unless I turned off the A/C. 214°F is still within "normal" operating temperature, but I (and my passengers) didn't much appreciate having to turn off the A/C. My alternator died while off-roading in the desert (2+ hours from the nearest town) forcing me to rely solely on the battery for engine cooling (as well as engine ignition, etc.) while driving in 4LO (producing minimal unassisted air movement through the radiator). The e-fan I was using could draw nearly 30 amps. After that, I decided that it is too risky to rely only on the electrical system for engine cooling on a vehicle whose main use is for driving off-road. 1 Link to comment Share on other sites More sharing options...
Mbrianc Posted March 8, 2017 Author Share Posted March 8, 2017 Here they are. I haven't cleaned the wiring up. Was waiting until I was sure it is operating correctly. Sent from my Nexus 5 using Tapatalk Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 8, 2017 Share Posted March 8, 2017 Yeah, that setup is not going to work. First, you have reduced the cooling efficiency of the radiator to only 52%, since nearly half of it has no forced-air cooling when the vehicle is not traveling fast enough to push air through the radiator. The radiator dimensions are 19x27 (give or take) or 513 sq in. Your fans cover only 267 sq in. [(14/2)^2 * 3.14] + [(12/2)^2 * 3.14] 267/513 = 52% Second, your temperature sensor is not located in the airflow of any of the fans. As I suspected, cool air being drawn through the radiator in by the fans is heated, then being partially exhausted forward out of the radiator where the fans have no coverage. You really need to get a shroud for those fans if you expect to have any hope of them keeping your engine cool in the summer. The shroud must be fashioned in such a way that there is negative air pressure on the entire radiator when the fans are on. That means you'll have to mount the fans to the back of the shroud, not directly against the radiator as you have them installed now. 1 Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 8, 2017 Share Posted March 8, 2017 If e-fans is something you really want to do, you would probably get better performance installing a single 16" fan in your original shroud than what you have now. But ultimately, you would get the most reliable results with something like this: https://www.summitracing.com/parts/der-16927/overview/ You'd need to check the clearance between the radiator and the steering box, however. When I had my Flex-a-Lite #295 installed, there wasn't enough clearance there and I had to trim off some of the fan shroud to fit it. You'll probably notice that the original fan shroud is flatter in the lower left corner for the same reason. 1 Link to comment Share on other sites More sharing options...
Mbrianc Posted March 8, 2017 Author Share Posted March 8, 2017 Yeah, I am starting to believe you are correct. I just put it indoors and used my fogger that I test my PC case airflows with. While there is substantial pull through the radiator, there is a draft of hot air coming out from around the edges of the radiator and immediately being pulled back in. Recycling its own hot air. So the answer would be to put at fan with substantially higher airflow, or seal around the radiator to prevent the engine bay from exchanging air with itself. Sent from my Nexus 5 using Tapatalk 1 Link to comment Share on other sites More sharing options...
Citron Posted March 8, 2017 Share Posted March 8, 2017 Great idea with the fogger. Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 9, 2017 Share Posted March 9, 2017 (edited) So the answer would be to put at fan with substantially higher airflow, or seal around the radiator to prevent the engine bay from exchanging air with itself. Yeah, such as this: https://www.summitra...16927/overview/ which does both Edited March 9, 2017 by XPLORx4 Link to comment Share on other sites More sharing options...
Mbrianc Posted March 9, 2017 Author Share Posted March 9, 2017 Oh yeah, I saw it. That bad boy is expensive. I can probably fab a shroud like that and purchase my own fans. Would need some better fans, but it could still be done for a good bit less than that. Sent from my Nexus 5 using Tapatalk Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 9, 2017 Share Posted March 9, 2017 Oh yeah, I saw it. That bad boy is expensive. I can probably fab a shroud like that and purchase my own fans. Would need some better fans, but it could still be done for a good bit less than that. Cool, keep us posted with your project status. I guess you know what's needed now to solve your issue: Full radiator coverage Shroud Fan(s) with adequate CFM Properly-positioned temperature probe Link to comment Share on other sites More sharing options...
Mbrianc Posted March 9, 2017 Author Share Posted March 9, 2017 I appreciate your input, and I will look into what can be done. Push come to shove, I can always put a new clutch and fan in. However those fans you linked would draw way too many amps for the stock alternator. And just out of curiosity, where should the probe be mounted? The position I chose was where the controller instructions indicated. But you actually have experience messing with these things. Sent from my Nexus 5 using Tapatalk Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 9, 2017 Share Posted March 9, 2017 However those fans you linked would draw way too many amps for the stock alternator. And just out of curiosity, where should the probe be mounted? Welcome to the slippery slope of vehicle modifications! I would install the probe in a part of the radiator that experiences air flow from the fans if you really want to have the fans cycle on/off properly at a particular temperature. It should be located as close to the upper radiator hose as possible. OR.... you could just give up and not be too concerned that the fans don't cycle on/off with the hood closed, and as long as the ECT is stable, don't worry about the fans staying on at idle. They do turn off when you're moving, right? Link to comment Share on other sites More sharing options...
Mbrianc Posted March 9, 2017 Author Share Posted March 9, 2017 Oh yeah, as soon as I take off the fans shut off. I'll play with it some more, but just in case, I ordered a new clutch and fan (aftermarket of course). Push come to shove, I'll mount one on the AC condenser for airflow at idle for the AC. Sent from my Nexus 5 using Tapatalk Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 10, 2017 Share Posted March 10, 2017 Push come to shove, I'll mount one on the AC condenser for airflow at idle for the AC. Push... literally. If you mount a fan in front of the AC condenser, it needs to PUSH air, not pull it. Sometimes depending on the fan design, you can just reverse the positive and negative leads so the motor runs backwards. However, some fans have blades designed to move air only in one direction. This is actually how I have my Pathy configured. I have the stock belt-driven fan and clutch, and a 12" pusher mounted in front of the AC condenser. It runs only when the AC compressor is on. Link to comment Share on other sites More sharing options...
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