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Did The Addition Of A Clutch Fan To The 258 Require A Different Radiator?

Discussion in 'Intermediate CJ-5/6/7/8' started by lhfarm, Dec 11, 2019.

  1. Dec 11, 2019
    lhfarm

    lhfarm Sponsor

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    Putting a later model 258 in my 79 CJ7. New engine has the water jacket manifold and fan clutch that has the blade very close to the stock radiator. I don't have the fender in place but I'm guessing that buttoned up it is only a quarter inch or so from the blade to the radiator. It is possible that I have the wrong clutch and blade, but wondering if there was a radiator change.

    Had the radiator checked while out and it is going to need to be replaced at some point. Wondering if I should just change it now.

    Thanks
     
  2. Dec 11, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    There is only one radiator for the 1979 CJs with a 258. In 1980, the radiator changes with heavy duty cooling or not (presuming HDC gets a thicker core). There is no fan clutch listed for any CJs with a 258 in 1979 or 1980.

    If your 258 is from a model later than 1980, there are parts books on the Tom Collins site that you can look up the applications info.
     
  3. Dec 11, 2019
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Not sure its relevant but the stock fan on my 304 is 1.5 inches from the radiator. The only time it ever was a problem I hit very very hard a pot hole on a gravel road, the fan damaged the rad. How it flexed that much that time is a mystery but it never happened again. I am thinking all of the radiators that would bolt up to your grill will be the same. Most likely the difference would be in the water pump or the fan clutch, any spacers or fan blades.
    Maybe timgr can help with this, he would be far more familiar with it than I.
     
  4. Dec 11, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Check your motor mounts. Put a wide board and jack under the pan and see if you can lift the engine separate from the frame.

    The six and V8 radiators are different, but the core support does not change. I suspect the main difference is in the location of the outlets.

    Pretty sure the fan should be located aligned with the edge of the fan shroud, if you have one. With a shroud, there's no need for the fan to be any closer than just in the shroud, which should put it an inch or two away from the radiator. Definitely right up next to the core is too close. Also, it looks like HDC in this era for the 232-258 was a different fan and possibly a fan shroud (the book is clear about the fan but not the shroud). Some Jeeps also change the distributor advance when equipped with HDC - you'd have to check the vacuum diagram and TSM for that year. Look for a HDC CTO.
     
  5. Dec 11, 2019
    lhfarm

    lhfarm Sponsor

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  6. Dec 11, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Since you are mixing a 1979 Jeep with a later engine, you will have to sort out compatibility on your own. If I had the '79 engine, I would take everything off the front of the '79 and bolt it to the newer 258 block. Then you could use the 1979 radiator without any issues of compatibility. Since there was no fan clutch for a '79, you'd have to delete it or figure out a combination of parts that works with what you have. If you want to use parts that match the engine instead of the chassis, there is a parts book on the Tom Collins site that covers those years. Look up the parts and cross the numbers.
     
  7. Dec 11, 2019
    sdcj6

    sdcj6 Sponsor

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    Hayden 2947
    This is a short fan clutch. I don't know if it is shorter than what you have but check at the parts store
    [​IMG]
     
    Last edited: Dec 15, 2019
  8. Dec 13, 2019
    sterlclan

    sterlclan Member 2022 Sponsor

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    I recall something about a clutch hub from a jag being a short one.
     
  9. Dec 14, 2019
    lhfarm

    lhfarm Sponsor

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    I've ordered a model from Radiator Express. They had "15 models" for a CJ7. Will see how it works.
     
  10. Dec 14, 2019
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    My 74 cj5 has standard cooling with a 4 blade fan and aluminium 2'' spacer in front of the water pump.
    Last week while pulling parts from a j-20 at a salvage yard for my power steering project I see it has HD cooling with fan clutch and 6 blade fan. paid 10 dollars for it. I noticed it appeared as unusually short setup.
    I measured and found it is the same length as my stock 4 blade fan and aluminium spacer was. Was able to maintain my 1.5 inch clearance of fan to radiator.
    on edit- I think it was a 1978 year J20 truck with a 360 in it.
     
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