Frost plug/Freeze plug size??
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Thread: Frost plug/Freeze plug size??

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    Default Frost plug/Freeze plug size??

    Hi guys!

    Frost plug, freeze plug, expansion plug, core plug, casting plug, whatever you prefer to call them: what size are they on a Cummins 4BT? I need the one on driver's side above oil pan in center. Thanks!!

    Oh, and I need size, not Cummins part number because I'll be sourcing through NAPA autoparts locally, thanks!

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    Quote Originally Posted by JimmieD View Post
    Hi guys!

    Frost plug, freeze plug, expansion plug, core plug, casting plug, whatever you prefer to call them: what size are they on a Cummins 4BT? I need the one on driver's side above oil pan in center. Thanks!!

    Oh, and I need size, not Cummins part number because I'll be sourcing through NAPA autoparts locally, thanks!
    If it's the larger sized ones I have some bad news Jimmie. The plugs are 58.06 mm which equals 2.285 inches. Past reports on other Dodge Cummins forums yields a fairly consistent failure rate by using 2-1/4 inch (2.250 inch) plugs because they install with a less than normal interference fit and actually push themselves out of the block under pressure and expansion within the block. I could never find a compatible sized Dorman tapered plug that would measure 2.250" on the small end and somewhere around 2.312" on the larger end.

    Reports are that Dodge sells them in the $5 or less price range and they are available from Cummins for around the same price, provided they do not charge a minimum shipping fee.

    EDIT NOTE: I can't get outside to the storage van to get a measurement because of freezing rain on ice so this info is from memory.
    Last edited by BobS; 12-25-2009 at 09:09 AM.
    BobS

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    First, stay in, stay warm, stay dry!!!

    No, that was some great info, I forgot that Dodge might carry them, Cummins tunnel vision!

    I can mic them out today, it was just cold & dark when I posted on it.

    I need to drill that particular one out for installation of a nipple, for the drainback on my Bypass Oil Filtration. May just go ahead and drill with grease on the bit & a magnet, any metal bits that slip by would just fall to the bottom of pan and stay there I imagine...? Worst case scenario, time for an oil change anyway, so drill, drain oil, drop the pan for a wipe & shine, call it good!

    Thanks, that's enough to tell me what I need to do!

    Meryy Christmas

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    Which plug are you looking for specifically? I'll see if my part book has it in there. Bobs memory serves him well, that is one size that is used but it's on the passenger side and rear. There are some behind the tappet cover or in that area if yours doesn't have the sound deadening cover. There is also the side oil fill port, but the Dodge Cummins engine mounting bracket covers that port and the manual doesn't specify the hole size... Which one?
    Last edited by sdstriper; 12-25-2009 at 05:01 PM.
    1989 D250 CTD, 727HD, D70/3.07, BHAF, DIY Cold air, Tuned VE, 4" exhaust

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    I think this one is possibly located in the center of the center mounting bosses. It's also a provision for an oil filler tube. I thought I had that size and part number in the index.
    BobS

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    I need the one on driver's side, above oil pan, in center. The one that's located in that raised casting area with the two threaded bolt holes. Can't remember what that cast area is for, but some auxiliary something or other attaches there. Used to know, before I lost my mind...

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    All I can currently come up with is a Cummins part number 3900958 but without any reference to size. I'll try and get measurement tomorrow. I have a block with that filler tube removed but it's buried deep in junque out in the garage.
    BobS

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    Please, Bob, don't bother! That area of engine on my installation is very easy to access for a measurement, no problem at all! There's no need for you to wrestle with stuff to get it.

    Also this isn't any kind of rush at all, I'm planning to install my bypass filter sometime in the next few weeks, not hours hah! So please don't bother with getting the measurement at all, it's much easier for me to do it here.

    I was only posting in order to start getting my Daffy ducks in a row on the install, very low priority. Thanks!

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    Looking in my Cummins Parts Book, Group 1, Cylinder Block for the plug JimmieD asked about, I find 3900958 which Bob also found. My parts book gives the dimensions of that plug as 32.02mm or 1.260"

    Paul

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    In another thread on here a member said he obtained his from NAPA. Jimmie, FWIW, if you go that route can you kindly post that NAPA or Dorman number on here for future reference? I hate open ended mysteries...........()
    BobS

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    Hi guys!

    Thanks, Paul! I can locate the part from that.

    Reason I wanted to get a new one for the mods is in order to braze a fitting in it, instead of trying to attach one by threading into a thin expansion plug.

    Yes, Bob, when I get it I'll post info here somewhere with part numbers etc.

    Thanks to you three wisemen...
    JimmieD

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    Ummmm... I guess I need a better parts book.....
    BobS

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    Paul has the same part number as my book, but my book does not give dimension for that expansion plug. That is the side oil fill. On the Dodge Cummins 6BT it is covered by the engine mounting bracket.
    1989 D250 CTD, 727HD, D70/3.07, BHAF, DIY Cold air, Tuned VE, 4" exhaust

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    "Ask, and you shall be receive, knock, and it shall be opened..."

    https://www.dormanproducts.com/cgi-b...72578&item_no=

    I think their I/T guy must get paid by the character?

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    Not much on the net for that 3900958 expansion plug.

    Mentioned in 2 Mil/Com Forward Support documents on heavy equip maintenance. Only a few applications use the oil fill blockoff plug, others have the filler connected there.

    Listed here:
    http://www.ptcpower.com/inventory/inventory_4_6bt.aspx

    Looks like maybe the 1.25" plug from Dorman sourced through NAPA is one answer, smack it sweet & easy to make it 1.260" and use sealant. No oil pressure or other pressure present there, so it won't take much to hold things in place.

    Of course a guy could knock out the plug, then use a simple flat steel cover plate with the nipple brazed in, sealed with paper gasket & some Permatex, and located by the two tapped screw bosses already there for retaining oil filler. Sounds like the best plan to me!

    Thanks for all help & suggestions!

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