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O/T engine overheating probs witha jeep CJ7.

Discussion in 'The Garage' started by ChevBlazin, Jan 5, 2004.

  1. ChevBlazin

    ChevBlazin 1/2 ton status

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    I know most of you dont like jeeps, I have a K5 also so give me a little credit. Need a little help with a problem the jeep is having. It has the 258 I-6 and at freeway speeds the temp gauge goes pretty high, close the the "H" IT is 6 below zero out and this is still happening. around town driving the temp stays at the middle of the gauge. I just replaced the thermostat tonigt and still same problem. after a ten minute drive and the gauge reading high I was still able to hold the radiator and hoses with my bare hands as well as parts of the block and head. is it possible the water pump cant keep up with the engine speeds on the highway? 2500 RPM @ 60 mph. maybe the water pump is bad. even in the summer the jeep ran cool around town. havent driven it since then but am forced to now since the blazer is down for a while. any help or ideas would be great. also the jeep has no fan shroud and the fan is a direct drive, not a clutch fan.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    IMO, water pumps don't "fail"...the seals fail, thats it. You might spin the impeller on the shaft, but I doubt it.

    Flex fans suck, and no shroud is even worse. Take the fan off, and go for a freeway drive, see what happens. You don't need it at freeway speeds (cruising, not towing etc) if the cooling system is adequate. Is the radiator clean on the outside? How about the radiator mix? Enough antifreeze (and new) to keep parts of the radiator from freezing?

    If parts of the engine are cool enough to touch, I'd perhaps suspect the gauge or sender, especially if the problem seems to be a sudden occurrence.
     
  3. ChevBlazin

    ChevBlazin 1/2 ton status

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    THe fan is the stock one, I also believe that a fan shroud was an option on early jeeps as this one and my previous one did not have them. Someone mentoned one another board that possibly one or more of the impeller blades rusted and or broke off on the water pump. That is what I meant by it failing. I also believe the coolant is close to a 50/50 mix, however I should probably verify that. If the sending unit or gauge are incorrect is it normal to have the temp vary so much when on the highway vs around town. If anything I would think it would be cooler on the highway, especially with the sub zero temps around here now.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Well if the pieces are stock for that engine, then something else is wrong. /forums/images/graemlins/smile.gif

    I only say gauge or sender because they may not reflect correctly, constantly. One of them may be "sticky" for instance, if thats even possible. I know senders can fail, and I know gauges can fail, and if the engine isn't hot like it should be at that reading, I would suspect the items monitoring the engine.

    If the engine has been taken care of, the impeller blades couldn't rust off. That's what antifreeze is for. I know reality is that most people don't take care of their cooling system as well as they should, but impeller blades are thicker than your sheetmetal, how long does that last?

    If you had an impeller blade come off, I would bet you'd know it. Haven't had the back off of anything other than an Oldsmobile water pump, but if a blade came off, nowhere for it to go, except be hit by the next blade.

    As to freeway vs. city, cooling and load are different in the two situations, you're sure the radiator is perfect internally as well? (only way to know is if it's brand new, or has been flow tested, honestly)Still, even that doesn't sound likely, if you aren't towing, load at cruise isn't that high, no worse than idling, but more airflow over the radiator.

    However, with a partially plugged radiator, I could see the higher fluid volume at cruise causing parts of the radiator to be "skipped" if they are plugged or severely restricted. Have you put your hand on parts of the front of the radiator to see if the whole thing is hot? Not scientific, but if a portion of it is cold, when it should be warm from coolant, you could have a radiator problem.

    I just wouldn't bank on any one cause until you can assure yourself that the sender and gauge are actually correct. Heck, could be a plugged exhaust or something equally unlikely, but there are always many options.
     
  5. greybeard

    greybeard Registered Member

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    I'm glad to see someone else has a CJ parked next to their K-5!!

    I would also check the sender and gauge. You can get both for about $25 from www.jeepdoc.com if you just want to replace them.

    I should add that my CJ does have a shroud and a clutch fan. However, mine is a 304. YMMV.
     

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