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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 47657
Experience:  16 years experience
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I have a 2008 Ford 6.4L diesel engine that was just rebuilt

Customer Question

I have a 2008 Ford 6.4L diesel engine that was just rebuilt and has a bad vibration at idle.
Submitted: 7 months ago.
Category: Ford
Expert:  Chris (aka- Moose) replied 7 months ago.

Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner till early morning.

What is the idle speed?

If you raise the idle with throttle applied does the vibration stop at a certain rpm?

At idle does it run rough like there is a misfire?

Customer: replied 7 months ago.
Idle speed it maybe 700 rpms and if you raise the engine speed it's less noticeable but still present. It does not feel like a misfire. It feels more like and in-balance somewhere in the engine.
Customer: replied 7 months ago.
The engine was recently rebuilt and we replaced all gaskets and seals. The only hard parts replaced were the bearings, piston rings,and 4 rods. The rods replaced were all on one bank.
Expert:  Chris (aka- Moose) replied 7 months ago.


Did the rebuilder use a vibration analyzer to try and figure out what is out of balance?

While driving is there a power loss?

Customer: replied 7 months ago.
No he did not use a vibration analyzer. He seems to think that since we didn't replace all 8 rods during the rebuild that that is causing the problem. I would think that with replacing the rods that they should all weigh the same regardless if they were replaced or not.There is no power loss when driving. It has plenty of power.
Expert:  Chris (aka- Moose) replied 7 months ago.


My suggestion is to use a scan tool to run a cylinder contribution or power balance test and relative compression test. If any cylinders show weaker than others then a manual compression test is needed. If one or more cylinders are low then you may have a bent rod which will cause that cylinder to have lower compression. Other possible causes are a damaged balancer or missing nuts holding the converter to the flexplate.

A vibration analyzer will be able to tell you the diameter and rpm of the part that is spinning out of balance once some math is done based on the hertz reading from the tool.

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Thanks for using Just Answer, Chris

Expert:  Chris (aka- Moose) replied 7 months ago.

Hello again Chris here,

  1. I have to assume you were not pleased with my help, because you have not replied or rated the post.
  2. What would you like to do regarding your question now?
  3. Do you still need help? Please reply I want you to get equal to or more than what you paid for.
  4. This post is coming up on the 7 day mark where it times out. That can prevent me from being able to post answers to your replies.

Thanks Chris

Customer: replied 7 months ago.
No it's not that at all. I'm just trying some of your suggestions on the truck but have not had time to get my mechanic down here to try them. He's coming down tomorrow to look at it and try some of your suggestions.
Expert:  Chris (aka- Moose) replied 7 months ago.

Thanks for getting back in touch with me. Keep me updated.

Customer: replied 7 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 7 months ago.
Chris are you available to chat?
Expert:  Chris (aka- Moose) replied 7 months ago.

I am now, what would you like to talk about?

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