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Thread: CJ running hot!

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    liljeeplover's Avatar
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    CJ running hot!

    I have a 1980 cj7 with a 304 v8 4spd. i just put a temp gauge in it because someone thought it was running hot. the temp gauge only goes up to 240 and that is what it is running at, maybe further because thats as far as the temp gauge goes. I have put a new radiator on it a couple months ago. and this morning just installed a 6 blade fan because it only had a little 4 blader. I was thinking maybe taking out the thermostat? any suggestions. the water pump is working. Thank you.

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    xt master's Avatar
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    Re: CJ running hot!

    Check to see if your temp sensor works properly and check your water pump to make sure it is circulating the water properly.Quick easy check of water pump is wait till the engine is hot and check the hose from the water pump to the radiator.It should be firm and warm.If it is very flexible your pump is not working properly.This is easier to check with out the T stat.If you leave the the T stat in you have to wait until the engine temp is above the temp of the T stat.

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    Re: CJ running hot!

    Is this temp. gauge a mechanical or electrical gauge?.. I'm running my 360 with a 185* t.stat with a mechanical gauge, electric fan off a 00 GC and an adjustable t.stat fan module, 4 core aluminum radiator and a flowkooler waterpump. The temp. stays around 190*-200* idling around the ranch..
    Confucious says: Don't eat the snow where the huskies go!

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    Re: CJ running hot!

    it is an electric gauge

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    Re: CJ running hot!

    Have you tested the coolant temperature sensor?. If the sensor is stuck closed, it wouldn't be much different if you just grounded the sensor wire. Check the resistance of the sensor when it's cold and again when it's hot..
    Confucious says: Don't eat the snow where the huskies go!

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    Re: CJ running hot!

    ok thanks for all the help i am changing the thermostat in the morning. ill let you know how it goes thanks again!

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    Re: CJ running hot!

    it is in the intake manifold sorry bout the confusion guys. i did change thermostat today.. i only drove it for about 10 minutes. by the temperature gauge which like i said reads max 240.. sat at 235? is that still too hot? i have no checked fan clutch and a mechanic did install the gauge and sending unit so it should be correct. when i boiled this thermostat for about 8 minutes it opened up about 1/2" is that ok?

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    xt master's Avatar
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    Re: CJ running hot!

    235 is way too hot...the max would be around 200..I live in the north so i run a 190 t stat..My gauge will usually get around 200 when I notice it start to fall..Have you checked the water pump yet?

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    Re: CJ running hot!

    Quote Originally Posted by liljeeplover View Post
    I have a 1980 cj7 with a 304 v8 4spd. i just put a temp gauge in it because someone thought it was running hot. the temp gauge only goes up to 240 and that is what it is running at, maybe further because thats as far as the temp gauge goes. I have put a new radiator on it a couple months ago. and this morning just installed a 6 blade fan because it only had a little 4 blader. I was thinking maybe taking out the thermostat? any suggestions. the water pump is working. Thank you.
    Try changing the T-stat first. A six blade fan might be better.

    After you've tried everything else you can think of, consider this;
    Bucky's "engine runs hot" fix.

    While it might not be your problem, it is a possibility. Besides, changing your freeze plugs can't hurt & you'll know for sure that it's clean in there.
    Forums/CORF Carolina's & surrounding states.
    Forums/CCOR Eastern Carolina's.

    I have more redneck mods than you!
    1990 YJ 4.2L AX-15 on board 220 amp alternator welder, York OBA with rear bumper air tank, Hitch mount front or rear XRC8, Junkyard tube doors, MC2100, TeamRush ign., 60" Hi-lift w/Jackmate, Homebrew cage add-ons, Homemade 1/4 ton trail rack, removable hood-windshield-tailgate, soda bottle coolant & W/W reservoirs Home built stinger & dual hitch front bumper..............

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    Re: CJ running hot!

    I just changed the thermostat and installed a flex six blade plan.. but im on pause now because i cracked my thermostat housing while tightening the bolts so that wont be here till thurs

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    Re: CJ running hot!

    There was a rather good article entitled "Custom Cooling" in the May 05 4wd and sport utility magazine mentioning fans, water pumps, radiators and so on. Perhaps there's a link on the web, although I was unable to find one. Likely other mag sites will have resources though.
    Quick fixes are so named for how long they stay fixed.
    If you run out of gas, no matter which way you decide to push, the closest gas station will always be uphill and in the other direction. Corollary: The likelihood of running out increases when all of the nearby gas stations are closed.
    The parts shop that stocks part for Skylab II will not have parts for our year/model of Jeep.
    We cannot accurately judge the trajectory of a speeding critter (cat, dog, sasquatch).

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    Re: CJ running hot!

    ..

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    Re: CJ running hot!

    How far is the fan from the radiator? Are you using a shroud? You did use a 3 core radiator with the V8? Does it get hot at idle or highway speed.. or both?

    I run a 3 core radiator with a stock 7 blade clutch fan and shroud. Jeep runs cool for the most part. Temp gauge will start to creep up if I'm on the throttle for an extended period (like a slimy hill climb) but otherwise it hovers around 200-210ish.

    If it stays cool going down the road, but overheats at idle, I'd look at airflow (as in fan) problems. Stays cool at idle but overheats going down the road, I'd look at water flow problems. If it overheats no matter what, I'd look at water flow (stuck thermostat or bad pump) and radiator capacity (maybe running a 2 core instead of a 3 core?).
    1980 CJ5, Injected 360, T176, D300 w/4:1, D44s, 3.73s, 33" LTBs, 4" RE lift w/RS9000 shocks.

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    Re: CJ running hot!

    are you sure the gauge is good? at 240 or so, i would expect a boil over. i'm guessing you're not running as hot as you think..
    Make mine an old CJ with a V8 and no top!

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    Re: CJ running hot!

    Ya come to find out that gauge didn't work, put a new mechanical gauge in and im running just fine. althought i did increase fan size and change thermostat so may have something to do with it

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    Re: CJ running hot!

    I discovered the primary reason for my slight overheating problem was the upper radiator hose collapses when the motor is under load. The reason I've never noticed it before is at idle, the hose looks just fine, but I happened to be blipping the throttle with my hand, checking for leaks and peered over the cowling and that's when I saw that uppper hose collapse. I reckon the high flow water pump I installed last summer has something to do with it. For remedy, I carefully bent up a wire coathanger (as I did for the lower hose) and inserted it.
    Quick fixes are so named for how long they stay fixed.
    If you run out of gas, no matter which way you decide to push, the closest gas station will always be uphill and in the other direction. Corollary: The likelihood of running out increases when all of the nearby gas stations are closed.
    The parts shop that stocks part for Skylab II will not have parts for our year/model of Jeep.
    We cannot accurately judge the trajectory of a speeding critter (cat, dog, sasquatch).

  17. #17
    xt master's Avatar
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    Re: CJ running hot!

    time to upgrade the hoses to some steel braided or the hoses that have the wire molded into the hose.

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    Re: CJ running hot!

    I do realize the problem was a bad gage, but I noticed the op is running a flex fan. I would say get rid of it and run a stock style fan with a shroud. flex fans do not pull enough air at slow speeds. I had a flex fan and changed it to a stock 7 blade fan from a 440. man did that move some air, I never ever had a temp issue after that. 1977 cj5 two row radiator chev 327
    Last edited by Ggg; 07-23-2009 at 11:43 PM.

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    Turbogus's Avatar
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    Re: CJ running hot!

    I bought a new Gates hose and custom bent some wire to hold the vacuum collapse. Also found the top tank developed more holes than the proverbial horse trader's mule. While I was at it I re-mounted my electric fan with fabbed brackets that go the the radiator mounting studs (got away from those tranny cooler zip tie things) on account that, what with the substandard quality of manufacturers of radiators, came to find that the torque of the fan was causing the zip ties to wear on the downtubes to the point of break through. Pity that 'cause it was a three row radiator. Luckily found another new one for $240 bones.
    Quick fixes are so named for how long they stay fixed.
    If you run out of gas, no matter which way you decide to push, the closest gas station will always be uphill and in the other direction. Corollary: The likelihood of running out increases when all of the nearby gas stations are closed.
    The parts shop that stocks part for Skylab II will not have parts for our year/model of Jeep.
    We cannot accurately judge the trajectory of a speeding critter (cat, dog, sasquatch).

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    Turbogus's Avatar
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    Re: CJ running hot!

    After running yesterday out on the highway and in town it seemed to range from 180 - 205 with the mods I listed prior. No surprise it'd be a little warm with the winch blocking some of the airflow. I'm hoping that it'll keep it's cool when the weather warms up again.
    Quick fixes are so named for how long they stay fixed.
    If you run out of gas, no matter which way you decide to push, the closest gas station will always be uphill and in the other direction. Corollary: The likelihood of running out increases when all of the nearby gas stations are closed.
    The parts shop that stocks part for Skylab II will not have parts for our year/model of Jeep.
    We cannot accurately judge the trajectory of a speeding critter (cat, dog, sasquatch).

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