white4d96 Posted July 17, 2011 Report Share Posted July 17, 2011 Okay, my car randomly runs hot. Not absurdly hot, but based on the gauge (which I wouldn't assume is calibrated right) like 230-240, city driving. If I kick both fans on it will hold steady there. Of course, as soon as I get some speed going it steadily drops. Coolant level looks fine, and it's been in there long enough I'm certain there's no air bubbles. I'm thinking either old coolant or sticky thermostat. Thoughts? If I replace the Tstat, should I go to a 180? If so do I have to reset the fan turn-on parameters, or is there another fan switch I can get? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 17, 2011 Report Share Posted July 17, 2011 what reading do you see while cruising at 55 or so? Quote Link to comment Share on other sites More sharing options...
white4d96 Posted July 17, 2011 Author Report Share Posted July 17, 2011 Smack dab in the middle or 200 on the gauge. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 17, 2011 Report Share Posted July 17, 2011 sounds like your themostat is working as intended then. you're just not getting enough airflow at lower speeds to remove heat from the radiator. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted July 17, 2011 Report Share Posted July 17, 2011 230-240?! Shouldnt both fans be on by ~227? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 17, 2011 Report Share Posted July 17, 2011 i just looked this up recently, but 96 3100 PCMs don't command fan #1 on until 108*C, fan 2 on at 111*C. that's 226 and 232 *F. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted July 17, 2011 Report Share Posted July 17, 2011 Seems a little high IMHO Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 17, 2011 Report Share Posted July 17, 2011 a hotter engine runs more efficiently. GM knew that and set the fans up to account for it. why they still stuck with a 195* thermostat and allow a 30* temperature swing before the fans come on, i don't quite understand. Quote Link to comment Share on other sites More sharing options...
BXX Posted July 17, 2011 Report Share Posted July 17, 2011 I bet your A/C condenser has years of shit stuck in it and bent fins restricting airflow. Quote Link to comment Share on other sites More sharing options...
white4d96 Posted July 17, 2011 Author Report Share Posted July 17, 2011 It's weird though, because my fan used to kick on just after the halfway mark and even stopped it would plummet. This is just over the past couple weeks it's started doing this. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 17, 2011 Report Share Posted July 17, 2011 something isn't transfering heat away as fast as it should. i also vote obstruction. Quote Link to comment Share on other sites More sharing options...
white4d96 Posted July 18, 2011 Author Report Share Posted July 18, 2011 I'll have to take a look around, see what I can find. I suppose it could be a random air bubble or something too, seeing how it'll be fine for days and then act up? No clue how it would have one, but I guess ya never know... Worst comes to worst I flush the coolant out and try out some of those slim-line fans I've always wanted to try. I highly doubt it will get to that point though. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted July 18, 2011 Report Share Posted July 18, 2011 I agree with Robert to look for an obstruction first... But over the years, I've replaced several fan motors that while still operating, weren't moving much air anymore, and the fan motor had to be replaced. But, finding and fixing an obstruction is free, so I'd start there. something isn't transfering heat away as fast as it should. i also vote obstruction. Quote Link to comment Share on other sites More sharing options...
BXX Posted July 18, 2011 Report Share Posted July 18, 2011 I'll have to take a look around, see what I can find. I suppose it could be a random air bubble or something too, seeing how it'll be fine for days and then act up? No clue how it would have one, but I guess ya never know... Worst comes to worst I flush the coolant out and try out some of those slim-line fans I've always wanted to try. I highly doubt it will get to that point though. A slimline fan cant even compare to our stock fans. It will flow like 1/3 of the CFM Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted July 18, 2011 Report Share Posted July 18, 2011 A slimline fan cant even compare to our stock fans. It will flow like 1/3 of the CFM What he said. If you want something slim, go with the intrigue fan shroud. Replace the thermostat ASAP with a 195 degree one. I tried a 180 degree for about 3 years and I never saw a benefit from the 195 degree on my N/A 3800. Quote Link to comment Share on other sites More sharing options...
BXX Posted July 18, 2011 Report Share Posted July 18, 2011 (edited) What he said. If you want something slim, go with the intrigue fan shroud. Replace the thermostat ASAP with a 195 degree one. I tried a 180 degree for about 3 years and I never saw a benefit from the 195 degree on my N/A 3800. 3100s dont like running that hot in my experience... Keep the 180 stat in there, go fetch a 97 Lumina PCM (3100/4t60e) from the junkyard and ship it to me man, I'll bench flash it for ya so you have lower fan turn ons among some other nice things:thumbsup: Come next weekend, i'll be all set to bench flash PCMs. I just need to get a few things so everything can be board mounted (terminal blocks, DLC, PSU, PCM Connectors) I already have a 97 Lumina PCM, but its mine!! :lol::lol: And cause of the delay with the mounts (I still wanna kill my welder) i'll do it free for ya. I couldnt drop off them to be welded today cause he's not in the shop today (what kinda asshole takes off Mondays????) Edited July 18, 2011 by BXX Quote Link to comment Share on other sites More sharing options...
white4d96 Posted July 18, 2011 Author Report Share Posted July 18, 2011 I'm still debating the Lumi PCM idea, but I have to figure out the emissions thing. Some people up here say I'll be fine, some say I need to put my VIN on the PCM or I will eternally fail. Quote Link to comment Share on other sites More sharing options...
BXX Posted July 18, 2011 Report Share Posted July 18, 2011 I'm still debating the Lumi PCM idea, but I have to figure out the emissions thing. Some people up here say I'll be fine, some say I need to put my VIN on the PCM or I will eternally fail. They dont read the PCM vin for emissions testing AFAIK. 99% of scan tools cannot see what the VIN is in the PCM file anyway My offer is free and open to you. Worse case scenario, you somehow fail and toss in your stock on, pass emissions, throw back in awsome tuned 97 Lumi PCM:thumbsup: Get off your rear, get to JY, pay $35 (average cost), ship to BXX, receive win!!!:lol: Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 18, 2011 Report Share Posted July 18, 2011 couldn't you change the VIN on the 97 PCM anyways? Quote Link to comment Share on other sites More sharing options...
BXX Posted July 18, 2011 Report Share Posted July 18, 2011 couldn't you change the VIN on the 97 PCM anyways? Yes, but HPT has checks in place that wont allow you to write a VIN to the file that is from a different OS. 96 being different, I dont think it will accept the VIN. Actually Austin, shoot me your 96 VIN, I have a stock 97 Lumina .bin (unmolested, un-vin'd, and uncompressed) that i'll try it on. Quote Link to comment Share on other sites More sharing options...
BXX Posted July 18, 2011 Report Share Posted July 18, 2011 Either way, there wont be an issue. Just use the stock PCM to pass emissions and then throw in the tuned 97 Lumi and be done with it, that's worse case scenario. Swapping out the PCM takes like 10 minutes tops. Quote Link to comment Share on other sites More sharing options...
white4d96 Posted July 18, 2011 Author Report Share Posted July 18, 2011 Okay. IIRC I have to pass every 2 years so 10 minutes every 2 years won't kill me. Better than swapping out an L67 every 2 years :lol: Um...my VIN? 1g2wj52m6tf221628 Quote Link to comment Share on other sites More sharing options...
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