6.9 idi replacement motor

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Charles Vogel, Nov 8, 2018.

  1. Charles Vogel

    Charles Vogel Registered User

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    I recently replaced my 6.9 that had a cracked block with a good one. It’s got the banks sidewinder and everything. My problem is the motor shakes violently and has a lot of pressure build up in the radiator when I turn over the motor. Any ideas what it can be?


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  2. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Sounds like a blown head gasket
     
  3. Charles Vogel

    Charles Vogel Registered User

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    I had just put in a new head gasket about a month ago when putting all new gaskets



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  4. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Did you check the block and head for straightness? Magnaflux the heads?
     
  5. Charles Vogel

    Charles Vogel Registered User

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    No, but the entire thing ran great before pulling it out of the donor truck


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  6. Chemgrad

    Chemgrad Full Access Member

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    I agree with thewespaul. The pressure in the radiator is generally indicative of a blown head gasket or a cracked head. Interesting that it ran well before. What was changed or added after it pulled?
     
  7. Charles Vogel

    Charles Vogel Registered User

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    I had put new head gaskets. Could that be the problem? I really don’t want to take it apart again unless I have to


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  8. Chemgrad

    Chemgrad Full Access Member

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    I've never had a 6.9 apart. TheWesPaul are those head-gaskets like the 302 handed? What I mean is the left has to go on the left and the right has to go on the right or flipped around? It really sounds like you're getting combustion gasses in your cooling system. Also odd that it is running rough now. Does it run rough at all RPM's?
     
  9. Charles Vogel

    Charles Vogel Registered User

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    Oh. I have no idea if they have a left and right. I have to see. But the rpms are ok. The motor is just running REALLY rough.


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  10. Chemgrad

    Chemgrad Full Access Member

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    Does it run rough at all RPM's or just at an idle? Sounds like it isn't running on one cylinder or more. Can you pull off the rocker arms and see if all the valves are actuating properly?
     
  11. Charles Vogel

    Charles Vogel Registered User

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    It’s running rough on all rpms. I’ll take a look at the rockers tho


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  12. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    You cannot get the head gaskets on wrong on these, but if you do not remove the head bolts opposite of the torque pattern the head may have warped, causing your hg leak.

    Get out a laser temp gun and shoot each of the exhaust ports. If you found one that’s different from the others by more than 50* you found your problem child.
     
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  13. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    If I'm right, there's an up and a down on the head gaskets, but not a right and left. The same with a 302.
     
  14. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Haha yep there’s an up and down, but I’ve found a couple head gaskets installed upside down when tearing down cores, no signs of issues with them flipped, but entertaining none the less
     
  15. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I've never heard of any issues either, but I ALWAYS take enough time to make sure that they're installed right. I just din't want to take any chances. Even if it's on a 302!
     
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