Cummins Big Cam 855 Lockplate Tightening Sequence Discrepancy

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Hilltop Hustler, Jul 6, 2025.

  1. Hilltop Hustler

    Hilltop Hustler Light Load Member

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    Is retrofitting it as simple as getting a smaller diameter hose or...?
     
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  3. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    No Sir, lot more to it than that. Low flow & High Flow are 2 different animals including the radiator.

    The front section of the water manifold is different as well, and the Low Flow manifold has restrictors under all 6 ports where it bolts to the heads. Finding the needed parts to convert would probably be a chore, not counting buying a radiator…

    IMG_0055.jpeg
     
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  4. Star Rider

    Star Rider Road Train Member

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    Took a side job once, guy wanted me to do an engine swap on a 1979 Transtar (this was a long time ago).

    What does he bring me? You guessed it an 88NT Low Flow.

    I told him it it will be very expensive and you will not be happy.

    I got it done, a 9670 low flow radiator shimmed up about a half inch works.

    Everything worked great until winter hit. Guess what? no heat! Not enough flow through the heater core.

    That was the best "I told you so" ever.
     
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  5. OLDSKOOLERnWV

    OLDSKOOLERnWV Captain Redbeard

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    When they worked properly they wasn’t bad, but they could be a bear when they didn’t. Those radiators have a divider in them, when the seal goes bad it can be hard to track down. That setup was Cummins stab at pleasing the e p a….
     
  6. Hilltop Hustler

    Hilltop Hustler Light Load Member

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    Apr 29, 2023
    West Virginia, USA
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    Is overheating a major issue?
    The person who I'm looking to contract with has a couple odd ball runs to Texas and Arizona during their peak summer heat
     
  7. IH9300SBA

    IH9300SBA Road Train Member

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    Never recall that being an issue with one, mine certainly doesn't suffer from it.
     
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  8. IH9300SBA

    IH9300SBA Road Train Member

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    Cummins was trying to keep the OEM's from having to design and install a CAC in order to accommodate their engine. The "coldest" water circulates through the JWAC to reduce intake air temps. The problem is, every part in the system has to be performing near flawlessly when summer temps hit, because there simply isn't enough volume of water to displace heat if it isn't if you're gassing on it.
     
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  9. Animosus

    Animosus Heavy Load Member

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    upload_2025-7-11_22-22-4.png

    Can't help with the other stuff, but here is your dataplate off quickserve.
     
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