Blaine Posted February 5, 2014 Share Posted February 5, 2014 87 Comanche 6 cyl 4.0 How long does it take for a jeep to warm up in 32 deg. weather? It seems to me that my truck is taking a long time to warm up. thinking it might be the thermostat but i replaced it not even six months ago. anything else might cause a slow warm up Link to comment Share on other sites More sharing options...
jimoshel Posted February 5, 2014 Share Posted February 5, 2014 Being in Maine, consider yourself lucky that it ever warms up. Otherwise I would say 10 minutes, you should feel heat from the vent. Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 lol true well mine def. took longer then 10 minutes, Link to comment Share on other sites More sharing options...
shelbyluvv Posted February 5, 2014 Share Posted February 5, 2014 If you put a FailSafe thermostat in it, it may be going bad. They are designed to fail in the open position. Link to comment Share on other sites More sharing options...
91Pioneer Posted February 5, 2014 Share Posted February 5, 2014 Idling or driving warm up time? Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 idling going down the road it won't go up to temp, prob. caused by the cold air being pushed through the radiator Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 I heard some cardboard in front of the rad would help keep it up to temp while driving, just don't cover the portion where the fan is so it don't overheat while idling. Link to comment Share on other sites More sharing options...
gogmorgo Posted February 5, 2014 Share Posted February 5, 2014 Sounds like a bad thermostat to me, or one for too low a temperature (should be 195°F). I can have heat from my blower within a few minutes of driving even at -32°F with the block heater left unplugged. I've never had it happen to me (knock on wood) but many people say they've had brand-new thermostats go bad on them. It's recommended to spend the extra money and get the Mopar one from a dealer. Cardboard in front of the radiator works, but it's a bit of a bandaid solution and doesn't actually fix your issue. Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 i have a 195 in it. ive heard of brand new t-stat failing too, so does it sound like it never fully closes to let the coolent reach temp. another thing once it is up to temp. should it ever fall back down a little like when the heater get turned on or when i start going down the road? Link to comment Share on other sites More sharing options...
sinkrun Posted February 5, 2014 Share Posted February 5, 2014 Flush the heater core, take off your hoses where they go into it at the firewall and using a garden hose spray water in each hole alternating back at forth. You most likely see brown crap coming out after a while do this for a few mins just not when it below freezing you don't what the core to freeze. Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 planned on it, its been flushed once a long while ago and crud came out of it. but should my temp fall go down once it up to temp. obv. it will a little when the heat is on but what about going down the road. Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 example: Today idling, heat off, it rose to temp (after a long while). turned heat on, temp went down but rose back to to running operation. now say its up to temp and i take off, the temp goes down to the line just above the 100 mark on my gauge. shouldnt it stay up to temp whether driving or sitting still? for the t-stat, to get the mopar one do u have to go to the dealership or would a place like autozone or carquest have one Link to comment Share on other sites More sharing options...
gogmorgo Posted February 5, 2014 Share Posted February 5, 2014 Given that he says the truck doesn't go up to temp, I don't think the issue is a plugged heater core, but flushing it can't hurt. Any reduction in flow due to a bad water pump or plugged coolant passage would, if anything, lead to the engine running hotter. The way the thermostat works is that it pops closed, blocking most of the coolant circulation until the coolant warms up, then it pops open, allowing all the coolant to flow through. I can watch this happen with my temperature gauge, as it climbs quickly up ~5° when the tstat closes and then slowly goes back down when it opens up again. On really cold days it fluctuates more, as the coolant looses a lot of temperature when the tstat's closed. Your truck came with a heater control valve on it. What it does is prevent coolant from entering the heater core when the heat is off. Many people choose to eliminate it because it can be finicky. But if it's still there and operating properly, when you first turn on the heat it will open and dump a bunch of cold coolant into the engine. I imagine this would be a noticeable temperature drop, but very short-lived because it's a fairly small amount of coolant going into a warm engine. My MJ's valve was already eliminated by a previous owner when I bought it, so the key words in that sentence are "I imagine". When you start driving, the extra air moving though the rad will significantly increase cooling, which will likely make the temperature gauge fall a little. Your thermostat should close before it drops too far, though. Given how far you say it's dropping, I'd say you've got a bad tstat. If you want to test it, you can pull it out. If it's open and cold, it's bad. If it's closed, then you can heat it up in a pot of water on the stove with a thermometer to see when it opens. If it's not opening within 5 or ten degrees of 195, it's bad. Avoid a non-stick pot for the sake of the pot and if it's you wife's pot, avoid getting caught for the sake of your health. ;) Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 perfect, i did plan eliminating that control valve cause there were some days it was up to temp and only warm air was coming through and other days nice hot air. i was just reading about this mod yesterday and said yep that's getting thrown out, which sucks cuz i replaced this not to long ago with a junkyard one cuz mine was leaking, if i had known this i would have bypassed it then. could i pick up a mopar t-stat at autzone or is it from the dealership? and trust me wouldn't catch me doing that with her pots cuz it would def. be the end of me, found out the hard way once :thwak: Link to comment Share on other sites More sharing options...
gogmorgo Posted February 5, 2014 Share Posted February 5, 2014 A Mopar tstat will only be available from a dealer. However, it may (or may not!) be the same as the MotoRad Fail-Safe tstat, which is a typical parts-store item. Can't speak as to whether or not Autozone will carry them as Autozone doesn't exist in my country. Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 how can u tell the diff. will they tell you? cuz if its the same as any part store i won't be paying dealer price for something i can get down the road for less, ive also herd of drilling two holes on each side if the t-stat, what does that do? Link to comment Share on other sites More sharing options...
gogmorgo Posted February 5, 2014 Share Posted February 5, 2014 Couldn't tell you the difference between the two. Someone stated recently on here that the Mopar tstats are presently made my MotoRad, and online pics show they look the same as the Fail-Safe, but I can't confirm the accuracy of that statement. Whether or not the same grade of parts goes to the dealer as to the parts stores is unknown. However it's not uncommon for parts manufacturers to sort parts as "adequate, good, and better", sell the "adequate" ones cheaply under a different brand, and divert the "better" parts to dealers so they can sell them for more. So you'll likely be getting a slightly better product at the dealer. Whether the potential difference is enough to justify the extra cost is up to you. If it's a difference of a long drive out of your way to the dealer vs a short walk to autozone, I know which one I'd choose. But again, it's up to you. You shouldn't need to drill any holes in the Fail-Safe or the Mopar, as it already has some kind of valve in it for the same purpose. I think it's for letting air bubbles out of the engine block, but I wouldn't know. They also say you should orient the holes/valve a certain way, but I didn't bother when I put mine (fail-safe) in back in November. I was on the side of the highway in -20°F windchill with no gloves and coolant everywhere because I'd just blown a hose (figured I'd swap it out while there was no coolant in it), so I just made sure it wasn't completely backwards and called it good. I have no idea which way the valve is pointed, but I haven't had any issues with cooling yet. Link to comment Share on other sites More sharing options...
Blaine Posted February 5, 2014 Author Share Posted February 5, 2014 so after ten minutes my truck temp needle didnt go up, after a minute of driving it started to rise, sound like a t-stat that once it warms starts to function right, and doesnt fully close, cause if it was fully open it wouldnt warm up at all Link to comment Share on other sites More sharing options...
gogmorgo Posted February 6, 2014 Share Posted February 6, 2014 Well, it might warm up... eventually. Sounds like a tstat stuck open, for sure. I timed mine this morning. Started it, let it idle for about a minute while I unplugged the block heater and I scraped the frost off the windsheild, then backed out of the driveway. Drove down to the end of the block, by which point the temp gauge had started rising. Two more blocks to get to the highway, sat at the stop sign for ~30s waiting for traffic, then accelerated to 60mph trying not to exceed 2000rpm. It took a total of 4m27s after I started it before the needle hit what would be the 210 mark on a US gauge. It was -15ºF and the block heater's on a timer as per my landlord (she sets it), so it was only on for about two hours. Link to comment Share on other sites More sharing options...
Blaine Posted February 6, 2014 Author Share Posted February 6, 2014 alright ill try another t-stat and hopefully it will warm up within a few minutes not a half hour, and stay up to temp Link to comment Share on other sites More sharing options...
sinkrun Posted February 14, 2014 Share Posted February 14, 2014 Any updates? Link to comment Share on other sites More sharing options...
Burntoast914 Posted February 14, 2014 Share Posted February 14, 2014 My 89 comanche same motor does the same takes about a hour or 45 mins to blow heat n then as soon as I switch heat to bi level or bent it starts to blow cold or if I stop at a stop light or sign so annoying but I changed my thermostat n it started to actually blow so much warmer but it still is cold after time to time Link to comment Share on other sites More sharing options...
cruiser54 Posted February 15, 2014 Share Posted February 15, 2014 The dealer stat #52028186 is NOT a fail-safe. Link to comment Share on other sites More sharing options...
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