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198 V6 Overheating

Discussion in 'Early CJ5 and CJ6 Tech' started by Bigdaddy13, Jul 31, 2020 at 12:43 PM.

  1. Jul 31, 2020 at 12:43 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

    So.Cal
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    Soooo, my wee little 198, that runs well and pulls hard up hills was taken for a nice spin yesterday. Went into town, gassed up, and stopped for treats for my kiddo's at a local store.

    Drove well, stopped well, but darn it all, started showing high heat on the way back getting up to about 220-240. Normally it's pegged in between 180-200. It was a hot day, but my expectation is that 200-ish would be the high spot.

    What I've done, as preventative maintenance a couple months ago, (but with no recent work and no recent overheating issues)

    1. New water pump
    2. New thermostat (installed correctly - I agonized over this)
    3. New upper and lower spring-lined hoses
    4. New bypass hose
    5. coolant system flushed and replaced with distilled water/new coolant
    6. New thermostat housing
    7. System was burped on a 45 degree slope, and topped off when warm
    8. fan belt is tight
    9. Shroud is in place.

    Thoughts?

    I'm not going to invest any big $$ into this motor, but I'm very OK with easy fixes...
     

    Attached Files:

  2. Jul 31, 2020 at 12:50 PM
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Assuming everything you mentioned above is okay, radiator is only thing left.
    Sounds like a possible circulation problem.
    With engine warm and radiator cap removed (caution) can you see movement off idle ?
    Is water moving thru the radiator?
     
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  3. Jul 31, 2020 at 1:01 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

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    That's a good thought. I have done zero other than flush the radiator. It's original to the car, i think.

    I've seen a coolant geyser that ended up burning my uncle right in front of me - so I'm very cautious, but truly thanks for the warning. I actually had the cap off once it cooled down and started the motor to see if I saw anything obvious like bubbling, leaks, etc. What would I be looking for off idle? the gauge temps spiking or?
     
  4. Jul 31, 2020 at 2:52 PM
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Increased water flow/movement with increased RPMs.
    Obviously, the t/stat needs to be open for movement to occur.
    We can't see deep inside a radiator to see how scaled up it might be.
    Restricted water passages restrict flow of water.
    Scale builds up and insulates the tubes and prevents heat transfer from occurring.
    Think insulation; if the hot water can't contact the metal tube, the heat won't transfer.

    Passages in the block could be restricted and/or scaled up as well.
     
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  5. Jul 31, 2020 at 6:09 PM
    Jonbbrew

    Jonbbrew Member

    Paso Robles, CA
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    X2...yes cap off and let the engine warm , even at idle, until the stat opens and see how it flows differently. Also might as well let a radiator shop boil it etc...

    Another side thought. Did you ever take the fan off where you may have put it on backwards? Just a crazy possibility that might make a difference.

    Also I know you said it was fine for a long while before but not sure what an original radiator would be since it’s an implant. Might need a bigger radiator but again that might just be why yours isn’t flowing well. Maybe something (debris) fell off from other places during flush and is getting lodged in radiator.

    Also might want to revisit thermostat placement. Why did the housing need to be replaced?
     
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  6. Jul 31, 2020 at 6:26 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

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    I’ll check the fan - good idea!
    Debris in radiator - very possible.
    Thermostat housing was leaky/corroded. Put a new Stant (Standt) thermostat in just for good measure.
     
  7. Jul 31, 2020 at 6:35 PM
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    If you decide on a new radiator, both the Falcon/Mustang and Fiero radiators are a popular replacement. Search for those terms and you will find a lot of discussion. Early Mustang radiator should be widely available and inexpensive, considering the popularity of those cars.
     
  8. Jul 31, 2020 at 8:15 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

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    Fan’s current position, with rotation direction noted.

    EFC05F0A-691E-4121-9B9C-D28DBE2FFA99.jpeg
     
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  9. Aug 1, 2020 at 8:05 AM
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

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    If it's properly installed, you should feel air pulled through the grille from the front. That said, with that rotation, the leading edge is toward the front; I'd say it's properly installed.
     
  10. Aug 1, 2020 at 9:55 AM
    Keys5a

    Keys5a Sponsor

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    If your cooling is marginal, a tighter fitting fan shroud can make a significant difference. I see a partial shroud in your photo, but one the covers the whole radiator and fit reletively close to the blade will make the most effeciency.
    -Donny
     
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  11. Aug 1, 2020 at 11:07 AM
    Jw60

    Jw60 Chim chiminey Chim chim cher-ee!

    Sedalia MO.
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    I recommend a quick cardboard fan shroud to test this.
    I've noticed a significant improvement in my 4.3 swap with a fan shroud on the '65 mustang radiator.
    If you can... grab an ir thermometer andreproduce the situation with overheating and check the temp everywhere the coolant flows. (Might want to videotape this)

    Have you checked the spark plugs?
     
  12. Aug 1, 2020 at 10:01 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

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    Put an impromptu shroud around about 50% of the opening. No difference. I did notice that its pulling a crap-ton of air towards the motor, and sits at idle just fine (no overheating)

    (Not saying it’s exactly what was recommended, but there’s no shroud on the bottom and this is all i had time for today.)

    got to about 220 before i shut it down.
     

    Attached Files:

    Last edited: Aug 2, 2020 at 1:40 AM
  13. Aug 2, 2020 at 10:26 AM
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

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    You need to see flow of coolant by looking down into the radiator. I would not trust the numbers on the temperature gauge - I'd use an infrared thermometer. A cheap and handy tool.
     
  14. Aug 2, 2020 at 10:48 AM
    boopiejones

    boopiejones Member

    California east bay
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    Where is the best place to check the temp with a thermometer? Temperature seems to vary significantly depending on where I point the thermometer.

     
  15. Aug 2, 2020 at 11:18 AM
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

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    That's not a bug, that's a feature! I would try it several places. At the thermostat housing or pointing at the temp sensor brass, I would expect it to be about the same as the gauge indicates. Supposed to be cooler leaving the radiator.

    The coolant returns from the block through the thermostat housing and into the upper radiator hose, so I would expect the thermostat housing and upper radiator hose to give you the highest reading. The temperature sensor should be right there at or in the thermostat housing, where it can sample the coolant carrying the engine heat.
     
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  16. Aug 2, 2020 at 11:45 AM
    Jw60

    Jw60 Chim chiminey Chim chim cher-ee!

    Sedalia MO.
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    Expect The area around the spark plug and the exhaust to be hotter than the coolant. Check that they are consistent between cylinders if anything. The back of the engine is a little hotter than front due to air exposure and less coolant flow. Thermostat should fluctuate when it opens as the hot coolant gets replaced by cooler fluid.
    An IR thermometer is indispensable with persistent overheating issues.

    Sounds like air flow is not Brian's problem.
    Yes Water flow needs verified and you might be able to mist the radiator when the engine is at 220 and watch the paint dry. If an area of tube takes longer to dry you know to backflush.
     
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  17. Aug 2, 2020 at 3:10 PM
    Jonbbrew

    Jonbbrew Member

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    Might also be able to test at various levels and from side to side on the radiator as you may be able to see where there could be a block. But in either case I would send to radiator shop for a boil and pressure test etc...cheap maintenance.
     
  18. Aug 2, 2020 at 3:21 PM
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

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    Meh. I wouldn't mess with it if it's plugged. Just replace it. Radiators are a commodity item today, and anything you try to do to this one will be at premium cost.
     
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  19. Aug 2, 2020 at 4:05 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

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    Thats my thinking, too. Not one to throw parts at a problem, but literally everything else is new with only about 20 miles on them


    Messed around with the radiator on my XJ for a week, then i realized you could get a lifetime Aluminum model from Autozone for $100.00. Had that car 4 years and 100k added to the odometer. Never had another cooling issue.
     
    Last edited: Aug 2, 2020 at 4:11 PM
  20. Aug 2, 2020 at 5:38 PM
    Bigdaddy13

    Bigdaddy13 Member 2020 Sponsor

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    Alright, well in spirit of buy once/cry once that i have resolved to have with this Jeep, my cooling system will be 100% brand new once this is installed.

    CC6571

    Took careful Tank and core measurements, noted the inlet/outlet sizes and locations, and ordered up. $260-ish out the door, on sale.

    might be dealing with other issues like a bad thermostat or pump, but those are easily found locally. Don’t want to have to question my radiator in the future.
     
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