97oldscutlas Posted April 1, 2012 Report Share Posted April 1, 2012 (edited) Hi guys! My first post! I joined cause i've been troubleshooting my 3.1 getting hot parked at idle. It'll stay normal temp or a touch hot when moving just about any speed or with the A/C fan or cooling fan on. It'll creep up to hot then fan kicks on and cools her back down. takes about 10 min. and it heats back up to hot and the cycle continues. Replaced t-stat and checked water pump, all is good. Flushed with new coolent. Belt tension seems good. Check engine light is throwing catalytic converter code. There is a hairline fracture on the radiator inlet that will leak initially, but then seal up from the heat. Radiator seems to hold good pressure and the cap closes off. I’ve not seen small leaks or even moderately low coolant cause heating like this. The radiator and reservoir is completely full and air bleeders only push out coolant at this point. Pretty sure it's gotta be the cat restricting exhaust and heating up my heads. Haven't done a vacuum test though. Do you guys recommend any other checks and what cat have you guys had good experiences with? Thank you! warmed up gets hot and fan kicks on after fan kicks off chillin' with A/C fan on Edited April 2, 2012 by 97oldscutlas Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted April 1, 2012 Report Share Posted April 1, 2012 You sound like you know a thing or two about being under the hood, that's a plus! The one thing you have to remember about these 3100s is that they require a very specific bleed procedure. They like to retain air in all sorts of places which can cause hot spots in the heads. It's been a while since I've bled a 3100, so I don't remember all the steps. The theory about the cat has merit, but I think you'd be having some sort of drivability issues if the cat was clogged. We had a w-body meet in Dayton, Ohio (last year, one I couldn't make it to) where a member had a clogged cat that was causing all sorts of problems. Bunch of guys wound up gutting the cat in the parking lot of a Wal-Mart LOL! As for a replacement cat, I'll leave that advice to people who've been down that road (all my cars are pre-downstream O2 ) Of course, you could always check your back pressure before and after the cat. That's a bit invasive though. I'll try and figure out the exact bleed procedure for the 3100, and post it up. I suspect a bleed may help your overheating issues before a new cat will. Oh, and the obligatory: Quote Link to comment Share on other sites More sharing options...
97oldscutlas Posted April 1, 2012 Author Report Share Posted April 1, 2012 (edited) thanks for the quick reply and advice, tornado. I've done quite a bit of work on cars and trucks, but don't work in the auto industry. I love knuckle bustin'. Hoping to draw from everyone’s experiences with similar symptoms. I let it run for good while and continually open the bleeder; let a lot of air out. Only shoots coolant now, but I’ll double check the bleed procedure too. I do have pics of the temp gauge at warm up, when it gets hot, then where it sits when done cooling off. I’ll upload those in a couple hours when I get back to the house. Thank you! Edited April 3, 2012 by 97oldscutlas Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 1, 2012 Report Share Posted April 1, 2012 I joined cause i've been troubleshooting my 3.1 getting hot parked at idle. It'll stay normal temp or a touch hot when moving just about any speed or with the A/C fan or cooling fan on. It'll creep up to hot then fan kicks on and cools her back down. takes about 10 min. and cycle continues. this sounds completely normal to me. when you're sitting still you have no airflow going through the radiator. if it stayed hot while moving, that's an issue. Quote Link to comment Share on other sites More sharing options...
AL Posted April 1, 2012 Report Share Posted April 1, 2012 How are the lower intake gaskets? Quote Link to comment Share on other sites More sharing options...
97oldscutlas Posted April 2, 2012 Author Report Share Posted April 2, 2012 posted the symptom pics RobertISaar, I don't think this is normal. radiator/t-stat should keep it at 195. something is causing it to get hot, but isn't major as the fan or air movment gets it back down. Another reason why i think it could be the restricted exhaust. i guess i will need to do a vacuum check to know.. AL, I'm not sure about the lower intake gaskets. wouldn't there be fluid exchange or get too much pressure or continual air in the coolant if my gaskets were bad? i guess i could have some plugged passages. is that a common on the 3.1? I have yet to do a compression check, but i don't think that would point me the direction of extra heat. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 2, 2012 Report Share Posted April 2, 2012 a thermostat only controls the lowest regulated temperature to allow. a 195 stat, when it reaches 195, won't allow the coolant to go under 195 again(unless the engine isn't making any heat by being shut off). if it does, then it's faulty. it does absolutely nothing to keep it from overheating, that's the job of the radiator. but if you're not moving, the radiator isn't receiving any airflow, so it can't disipate the excess heat, so that's why the fans are commanded on. Quote Link to comment Share on other sites More sharing options...
cutlassdude96 Posted April 2, 2012 Report Share Posted April 2, 2012 this sounds completely normal to me. when you're sitting still you have no airflow going through the radiator. if it stayed hot while moving, that's an issue. I agree with this statement. Mine does the exact samething. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted April 2, 2012 Report Share Posted April 2, 2012 Yeah, just looking at your pictures, your temps are running just fine. If you were creeping up anywhere above about the 2nd white tick mark, up towards the red, then you might want to start worrying a little bit. And like I said, you would know if you had a clogged cat because you would have more drivability issues. The car just wouldn't run right at all if there was a restriction in the exhaust. Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted April 2, 2012 Report Share Posted April 2, 2012 have you looked at your radiator? is there alot of junk caught up in it? My 94 has never gotten that hot even while sitting in summer traffic so it cant be normal. Maybe youve got some build up in there as well. Quote Link to comment Share on other sites More sharing options...
97oldscutlas Posted April 2, 2012 Author Report Share Posted April 2, 2012 (edited) I really apprecitate your feedback. I was wondering if i was jumping the gun here, but when i drove a 3.1 and in any other car I've not seen the temp creep that high and continually rely on the fan unless it’s a scorcher out. I think i'll do a vacuum test to satisfy my curiosity. One of my neighbors has a 3.1 was considering doing a stare and compare. Planning on replacing the radiator anyways, so let me try that first and we'll see if this system is that sensitive. Thanks guys! You’ve put my mind at easy. I’ll take my time checking the rest over. But incidentally, when I do need to replace the cat, is there any that anyone would recommend or at least recommend avoiding??? Edited April 2, 2012 by 97oldscutlas Quote Link to comment Share on other sites More sharing options...
97oldscutlas Posted April 2, 2012 Author Report Share Posted April 2, 2012 (edited) same thing i was thinking, seems out of spec to me.. i was considering the same about the radiator, but then all it needs is a touch air and cools right down. so i figured the radiator is doing its job, but was thinking something must be bumping the heat up on the coolant.. There is a hairline fracture on the radiator inlet that will leak initially, but then seal up from the heat. Radiator seems to hold good pressure and the cap closes off. I’ve not seen small leaks or even moderately low coolant cause heating like this. The radiator and reservoir is completely full and air bleeders only push out coolant at this point. Planning on replacing the radiator anyways, so let me try that first and we'll see if this system is that sensitive. Thanks! Edited April 2, 2012 by 97oldscutlas Quote Link to comment Share on other sites More sharing options...
ricklovin93 Posted April 2, 2012 Report Share Posted April 2, 2012 theres nothing wrong with your car, my cutlass does the samething, its just the way the cooling system is, when idleing you get no airflow through the radiator which increases coolant temp, so the fans kick on at a certain temperature, which then cools the coolant back down, just like what robertisaar said Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted April 3, 2012 Report Share Posted April 3, 2012 this sounds completely normal to me. when you're sitting still you have no airflow going through the radiator. if it stayed hot while moving, that's an issue. QFT. All my cars behave this way, and the reason is just what Saar said; no airflow through the radiator. Now with that crack in the radiator, you are likely going to get air back in the system so you are definitely on the right track to replace it. Quote Link to comment Share on other sites More sharing options...
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