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IDI Serial Numbers

Discussion in '6.9L IH & 7.3L IDI Diesels' started by catbird7, Apr 7, 2015.

  1. catbird7

    catbird7 Full Access Member

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    I finally took the time to clean off the engine blocks on both of the IDI's I have and discovered the 6.9 engine I thought I had is actually a 7.3. Now I'm wondering just exactly what I have. The engine I removed from the 1989 F350 has serial number 7.3DU2U6239461 and the engine currently installed in the 1987 F250 (which I thought was a 6.9) has serial number 7.3DU2U617160* . Yes, the engine in the 87 appears to have an * at the end of the serial number. So, the questions I have are: #1.) Does the * mean anything? #2.) Can anyone decipher these numbers into anything meaningful?
     
  2. OLDBULL8

    OLDBULL8 Good Morning Ya'll. Supporting Member

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    The * could mean that the engine does NOT match the VIN number. In other words, the truck came with a 6.9 and a 7.3 was swaped into it. Googling the serial numbers didn't come up with anything.
     
  3. catbird7

    catbird7 Full Access Member

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    It has 6.9 valve covers on the engine so I assume these were from the original factory installed engine. Aren't most "crate engines" supplied without valve covers and oil pans? Maybe it was a crate engine from somewhere and the original tins were re-used??? Still curious about the * at the end of the serial number. I googled it and found nothing useful and hoped somone on here would know. I assume the serial number is stamped by Navistar and theorized the * denoted a factory (Navistar) reconditioned engine. (Wishful thinking!)
     
  4. madpogue

    madpogue Full Access Member

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    The engine number NEVER matches the VIN. The engines were made and shipped in bulk by IH, with the numbers assigned/stamped by IH. It's unlikely they were installed in the trucks in engine number order, so there's no relationship between VIN and engine number. I'm thinking the * is a place-holder for six-digit serial numbers (the part after the U). My engine is a Dealers Diesel reman, which had its own DD number on a badge riveted on top of the OEM number. The OEM number is six digits after the U, and has a * on the end. The "renumbered" engines that have shown up recently have either been with a separate badge like mine, or with the original number ground off, and a completely different number stamped in three rows (see IDIoit's recent thread).
     
  5. madpogue

    madpogue Full Access Member

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  6. OLDBULL8

    OLDBULL8 Good Morning Ya'll. Supporting Member

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    WRONG AGAIN.
    Who the hell said the engine serial number is in the VIN number.
    Checking the VIN number will tell you whether the truck came with a 6.9L or a 7.3L diesel.
    Read it again.
     
  7. KGIA103

    KGIA103 Supporting Member Supporting Member

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    What ever happened here? Why do some serial numbers have * at the end? Diesels destined for trucks had a 6.9DM2U... What does 6.9DU2U mean about the engines original intended use?

    I'm sure we all a kick out of searching through old threads only to be left hanging.
    Thanks.


    Edit : I have been set straight on M2 and U2...
    M for Internationals and U for Ford.

    Still wondering if they all have *...and why there are so many threads without conclusions? Ha Ha.
     
    Last edited: Jan 15, 2018
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  8. Tom Clifford

    Tom Clifford Registered User

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    I don’t know anything about the asterisk, YET, but I found this:

    7.3L IDI 1988-1994
    Block c/n 10809000C1 was used for the entire 7.3L IDI years of production. The serial numbers for naturally aspirated applications are 500,079 through 1,116,330.

    Mine is: 73DU2U509783, which, I believe, was, originally, installed in 1988 F250s, F350s, etc.
     
  9. chris142

    chris142 Full Access Member

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    The Astrix could mean anything. Mopar added different designations for an under size crank journal or an over size lifter hole.

    Maybe ihc did too?

    Yours may be an employee added it for fun after he test ran it. Or maybe a different plant built it etc.
     
  10. snicklas

    snicklas 6.0 and Loving It!! Staff Member

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    I think what the asterisk is for is a placeholder/modification deterrent.

    If the asterisk is at the end, then it would be more difficult to modify the serial number. Since there are changes that have a serial number break, some of those breaks are significant. I could see IH wanting to prevent modification, since there is the block heater/webing break. The pressin/bolt in oil squirters........ I could see a less than honest seller try to make the serial number “newer” on and older engine to make it more desirable.....
     
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  11. ttman4

    ttman4 Last Nite's Dream..

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    That's what I think^^^ My '94IDIT engine has a * at the end & I have seen an * on other 7.3s
     

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