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P0303 Weird Misfire

Old Mar 9, 2021 | 09:19 PM
  #31  
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Originally Posted by buickman32
So I really cant reuse the LIM and UIM even if its brand new less than 300 miles on them? I can't just clean them off and clean the surface again? I am sure they are in good condition still.
If you are talking about the gaskets they will be no good. Once they get hot the seal is formed and will never seal again once the seal is broken a new gasket is all that will fix it.
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Old Mar 9, 2021 | 09:27 PM
  #32  
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Jeez that is really upsetting to hear..
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Old Mar 9, 2021 | 09:29 PM
  #33  
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In most cases, when torqued, the gaskets are “crimped” or compressed which aids in the sealing of the gasket. This can vary as to what type of material the gasket is made from. The lower intake gaskets for example have a critical job to do in preventing water from entering the combustion chamber. I would not want to run the risk of facing yet another tear down if the gasket did not seal properly. There is too much to lose in my opinion with over 50 years of mechanic experience.
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Old Mar 9, 2021 | 09:31 PM
  #34  
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I understand. I just wish I did a compression test in the beginning of all this. All the articles I read said to test that last. Expensive lesson I guess.
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Old Mar 9, 2021 | 11:02 PM
  #35  
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Compression is one of the first things to check in a misfire. I do static and running tests.
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Old Mar 15, 2021 | 06:20 PM
  #36  
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SOLVED: After all this work, the issue is finally resolved. Wet compression test lead me to believe a valve issue. Pulled the valve cover and begun removing the rocker arms and pushrods. Cylinder 3'* exhaust pushrod was completely bent. I pulled the head off to investigate further and found the exhaust valve to be intact and not burnt. Investigating further, I pulled the spring off exhaust #3 and found the the valve stem to be completely snapped off. Went to the junkyard, pulled a new head, transferred everything over and put it back together. Drove back to school today and had: no coolant leaks, engine light, idle vibrations, and better MPG. Computer clocked me in at 29.7 MPG after the trip so I am happy. Conclusion: do a compression test first when diagnosing a misfire.
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Old Mar 16, 2021 | 09:05 PM
  #37  
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Thanks for posting your findings after the tear down as well as completed project. I am happy for you concerning your project with a successful outcome.
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Old Mar 19, 2021 | 12:30 AM
  #38  
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Thanks for letting us know how it turned out! Looks like you did a pretty thorough job diagnosing and repairing.

Keep an eye on coolant and oil for a little while in case there is a leak.

Any idea what caused all of this destruction?

Is the piston okay?
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