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Discussion Starter #1
Hi all, I bought my first jeep TJ (2004) yesterday and while driving home the engine light came on. Took it to a nearby mechanic and he mentioned that there is a miss fire in cylinder 5 and 6. He also mentioned that there is a knocking noise coming from the lower back of the motor.
Essentially he told me that my motor is gone and that I would need to rebuild or replace.


Just wanted to know what you guys think. Is my motor gone? It’s the 4.0L with 82000 miles.
thanks
 

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What, specifically did the mechanic say was wrong? Piston skirt? Crank bearing?
 

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Discussion Starter #3
The mechanic did mentioned that it could be a bad bearning. He also mrntioned that he would need to open up the motor to find out more details. At this state Im worried that I bought a Jeep.
 

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Did you not inspect it before you bought it? You can always get your money back, unless it is an as where is deal, which should have prompted you to ask a qualified mechanic go through the car with a tooth pick. Good luck.
 

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Depending on how it was maintained and treated, yes, engine could be bad at 82k miles. If you've only had the vehicle for a day or two, I'd be taking it back to wherever you bought it. If it was a dealer, depending on your state's laws, you may have a 3 day return period. If you bought it from a private individual, assuming you can find them, you may or may not be able to return it. You may need to talk to an attorney before its all over.
How well do you know/trust the mechanic who gave you the diagnosis? He could be right. If he is, there could be other expensive problems just waiting to be found. Again, a whole lot depends on how the previous owner(s) took care and treated it. Know you've heard it before but you've really got to check a used vehicle out thoroughly, and especially an off-road vehicle like a Jeep, because many prior owners tend to not properly maintain and/or abuse and beat hell out of them. And if you don't know what to look for, get someone who does to help you.
 

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Good advice above. If you are stuck with it, start with a oil change. Pull the spark plugs for 5 and 6 and see if they are clean and hopefully gray in color. If they are oil soaked or black change them. The check engine light only tells you about the condition of the emission control system. It does not know if you have a knock or bearing issue. Issues with a head gasket or rings could cause those cylinders to burn "dirty" and trigger the check engine light. Typically with the check engine light there will be a code associated with it. Autozone will typically plug in and read the code for you. If the plugs dirty again there likely is a more expensive mechanical problem. Valve seals, cracked head, head gasket, worn or broken rings are the most likely. An issue with the crankshaft bearings should not cause a check engine light ever. Misfires can be caused by the plugs, coil pack, or fuel injectors. Fuel injectors and coil packs are easy to swap around for trouble shooting. If you move a part and the problem follows the part you have your answer.
 

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Discussion Starter #7
Thanks all for your feedback. Really lesson learned. I am taking it to another mechanic for a second opinion.
 

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Discussion Starter #9
Ive changed the spark plugs and so far no engine light. The motor sounds smooth. I don't hear any knocking noises
 

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Ive changed the spark plugs and so far no engine light. The motor sounds smooth. I don't hear any knocking noises
Great! Probably wouldn't go to that mechanic in the future. . .
 

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Great! Probably wouldn't go to that mechanic in the future. . .
+1 If the engine is still quiet and running well I would pay the first mechanic a visit and tell him he blew the diagnosis and lost a customer.
 

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+1 If the engine is still quiet and running well I would pay the first mechanic a visit and tell him he blew the diagnosis and lost a customer.
Lesson learned lol
I am on this forum to avoid mechanics completely. My next door neighbor has been a mechanic for 25 years. But the kind folks on these forums know these Jeeps inside out. So I look and search here first.
 
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