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Frankenstein 454 swap. Overheating at idle.

Discussion in 'Tech Discussion' started by 83Burban, Apr 11, 2021.

  1. 83Burban

    83Burban Full Access Member

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    Some background...

    Ive got a nearly rust free 1983 4x4 Suburban. Based on the vin, it started its life as a 6.2 diesel. Previous owner swapped out for a 454 w/ th400. (think it's all from the 70s, have not yet been able to find numbers). Ive owned for a couple months now and am still trying to work out some bugs. Namely, over heating at idle. Its been this way sense I purchased it.

    I have zero clue if this thing is "built". But has Edlebrock performer 2.0 intake w/ 750cfm 1407 Edlebrock carb (fresh rebuild). Was converted to Serpentine. Has AC (front and rear). Recently replaced leaky oversized copper rad for new aluminum rad with dual fans. New hoses and thermostat. New plugs and wires. And recently had the manifolds and 2.25" dual exhaust swapped out for ceramic flowtech long tube headers and 2.50" pipes (off brand mufflers are not doing a whole lot ).

    Now....the serp conversion looks....well, kinda crude. Im not real sure if it was an actual kit, or if they cobbled it together. There is a huge run across the top that really seems, wrong. And I think they might not have installed a "reverse flow" pump....and serp is for sure turning it counter clockwise.

    Truck does just fine running down down the highway. Stays right at 185°. When I get in traffic or even just slow down to a crawl in a parking lot or drive way...the temp climbs up to 220-240 in pretty short order.

    I'm going to replace the water pump regardless. Really hoping someone might point me in the direction of a quality reverse flow? Part numbers are awesome. Found an edlebrock victor series (part # EDL-8854). Will this fit my application? 20210411_161548.jpg 20210411_161534.jpg 20210411_161413_HDR.jpg 20210411_161249_HDR.jpg
     
    Last edited: Apr 11, 2021
  2. Matt69olds

    Matt69olds Full Access Member

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    Make sure the fans are wired correctly, and make sure the fan blades are on the fan motors correctly.

    Most aftermarket fans can be used as pusher or pulleys, you need to wire the motors correctly AND have the fans on the motors with the right orientation.

    I’m not a fan (ha!) of aftermarket fans. The rated cfm of dirflow is VERY optimistic. Combined with no fan shroud, they tend to pull air from around the fan instead of air thru the radiator.

    It’s hard to beat a factory fan with a thermal clutch and the proper fan shroud. These trucks didn’t overheat when new, assuming everything is set up the way the factory designed it shouldn’t overheat now.

    The fact that it runs cool on the road proves you have plenty of cooling capacity. It heats up at idle, suggesting the problem is low speed airflow.

    If you just have to have electric fans, find something from a late model truck or car with a fan/shroud that covers the entire radiator. Make sure the shroud fits tightly against the radiator. Make sure any air the fan does pull actually comes thru the radiator
     
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  3. Turbo4whl

    Turbo4whl Supporting Member Supporting Member

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    Engine and water pump from the 1970's? Yes it is spinning the wrong way. Depending on the design of the pump impeller, it will move some coolant backwards.
     
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  4. Matt69olds

    Matt69olds Full Access Member

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    Crap, I forgot the serpentine belt/water pump compatibility issue.
     
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  5. 83Burban

    83Burban Full Access Member

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    Tbh im not 100% sure on the year. Ive yet to find any markings on the block or otherwise. Im assuming that this pump could likely be an aftermarket pump. I'm just fairly sure that its not designed to spin in reverse.

    Matt69olds .....Ive checked and double checked the fans. They are pulling through the rad the proper direction, and they do kick on like they are supposed to. Idk if you can see it very well in the attached pictures. But this is a pretty beefy rad / fan set up. I went this route because it should have been overkill for this truck. Ill see what I can do about closing the gap in the shroud. But, Im nearly positive my issue lies elsewhere as this was an issue with the previous rad / fan combo and that shroud did fully cover rad with no gaps. The fans were just junk, and the rad was leaking.
     
  6. Powerhouse Ranch

    Powerhouse Ranch 3G Connoisseur Supporting Member

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    holy serpentine belt!
     
  7. Turbo4whl

    Turbo4whl Supporting Member Supporting Member

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    Looking at your picture again, the serpentine belt drive is not factory. Homemade, not working with that water pump. Also does not have a very good rap around the power steering pump pulley either.

    I believe you need to address the belt drive system.
     
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  8. Wumbo

    Wumbo Full Access Member

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    looks like a gen 5 454 with some homemade accessory brackets.

    I would start with the water pump.
     
  9. 83Burban

    83Burban Full Access Member

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    This is my first time dealing with a serp converted truck. Also my first GM so im a little behind on the curve. Well, i've got a 55 Bel Air Convertible. But they are only similar in that they both have a bowtie on them.

    My theory is that the water pump is not designed to spin this direction (counter clockwise). So when the motor is not turning very fast, its gotta be moving very little water through the engine. That or maybe it is a reverse flow pump, and its just slipping? Regardless, Im going to change it anyways. Just really don't want to spend $$$ on a pump that wont fit this mess.

    As far as this serp system as a whole....any chance there is some kind of extra pully that could be used to take up some of the slack on the top run untill I can get a propper kit?
     
  10. 83Burban

    83Burban Full Access Member

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    I really have no clue on the motor. Did get new motor mounts while in the shop getting exhaust but was told they had to get mounts for a 70s vintage suburban? I just kinda assumed the motor would have been from that era based on that.

    But I'll take your word for it. I'm still learning how speak Chevy. Its been.....interesting. Lol
     
  11. Turbo4whl

    Turbo4whl Supporting Member Supporting Member

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    So I looked at my serp belt on the 454 in the '98 3500. It also spins the other way (like your's) compared to the '71 BB I have in the '82. The '82 has V belts.

    Most all serp belt systems have a spring loaded tensioner.



    [​IMG]

    I am sure that long straight run of your belt bounces.
     
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  12. Bextreme04

    Bextreme04 Full Access Member

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    That is some ghetto homemade serpentine mess. It should be a reverse rotation water pump from a Gen V or Gen VI 454 in order to flow properly. My replacement water pump for my 1997 Gen VI 454 is a NAPA PN#44030. You should definitely have a spring loaded tensioner like pictured above, you also shouldn't have that long of a run.
     
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  13. 83Burban

    83Burban Full Access Member

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    Yeah, its got a little bounce to it. Ive beem looking for one. But I'm not really sure which one I need, or where the tensioner should mount exactly. Lol ive not found any pictures or examples that resemble what ive got going on.
     
  14. 83Burban

    83Burban Full Access Member

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    I ordered an Edlebrock Victor series reverse flow pump late last night. Hoping it will do the trick. If it does not do the trick I'll look into that one.

    Any body got a part number on a tentioner that should work?
     
  15. Turbo4whl

    Turbo4whl Supporting Member Supporting Member

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    You probably will not find pictures of a belt drive system like yours. If it is working for now, wait until you get some cash and time to get it back closer to stock. Visit a wrecking yard and find a truck with what you need. Save the water pump you remove, that way if you spot a complete V belt system, you could use that system too. V belts have been doing the same job for years.

    Here are pictures of my '98 Hobby Wrecker. This is the factory system for the GMT400 that year.

    20210412_161026.jpg

    20210412_161039.jpg

    20210412_161046.jpg

    Yes, dirty engine, but it runs well. Pushes the 15,000 lb GVWR 3500HD where I want it to go. Oh, and yeah I've never had it overloaded.
     
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