Burnt valve

ok I just love stuff like this,,,,this X5 with a N55 engine has been already at 3 different dealers for misfire on cylinder 1,,,,each dealer would replace ignition coils,,,spark plugs or fuel injector and they would ship the car saying it was fixed,,,,so my dealer gives me the car and tells me to find out what the problem is,,,,I knew 3 different set of spark plugs and ignition coils and injector did not fix the problem,,,,so I decided to check compression test,,,found 80lbs on cylinder 1,,,performed cylinder leakage test we had 80 percent leakage on cylinder 1,,,,I checked the intake no air leakage,,,checked the exhaust and found air coming out,,,ok now we know we have a problem internally with the engine,,,I installed a borescope to check out the valves but was unable to see anything,,,,so I had to remove the cylinder head and this is what I found,,,problem found,,,,happy customer

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19 Responses to Burnt valve

  1. Musti says:

    Ooh man, stories like this. The satisfaction. Keep posting this man. Any ideas how the valve get burnt like that? Because of my main work, I can’t work on cars often, but reading your experiences are keeping me alive. I had valvetronic issues with my N55 and you helped me sort it out months ago, thanks again for that. Happy follower from Belgium.


  2. JC says:

    Wow. That’s a first for me. Was there a lot of carbon in the combustion chamber?


  3. Sam G says:

    Good job 👏!!!


  4. F30ed says:

    Is it defective valve or is it burnt by using wrong fuel? What is the reason?


  5. Bart Bixler says:

    Disappointing that the other so called qualified BMW dealers tech’s could not find the problem, nobody is teaching basic troubleshooting anymore.


    • Don’t get me started on this subject,,,lol,,,,this is a major problem with the newer and younger BMW techs,,,,they just know how to replace parts it’s a very sad issue in this business.


      • Alan says:

        Just blindly replacing parts makes more money mate!

        Your kind will be run out of town if you keep looking after the customer like that!!

        Bloody good work mate. Keep it up.

        Your blogs are always a great read man.


  6. Lee says:

    Ha- the others made it ez for you. Had one years ago- replaced the coil and plug but not the boot connector (was the earlier two part coil/boot).
    Worked for a while. Then went to the dealer. They finished what I started by replacing the boot. Some spark plug insulators come loose and allow hot exhaust gas to escape up and when everything is cold and damp from humidity it will blow moisture under the boot and cause carbon tracking/arching = random misfire. When BMW started using the one piece coil the problems missed by trying to save a customer money by reusing boots went away.
    While a bit off course it’s the same subject but my point being a smart tech reviews whats been done and moves forward.
    My question is: how many miles?
    My experience is that it’s possible a bad injector could cause this (lean = too hot) but a new injector won’t fix it but a new injector should be used or risk a repeat- unless stats prove a bad batch of valves which BMW may or may not share info.
    Keep up the good werk and thanks for sharing!

    Liked by 1 person

    • I don’t remember the mileage but it was still covered under BMW warranty,,,BMW has found out the problem is a bad batch of exhaust valve.


      • concerned says:

        This would have been one heck of an expensive odyssey if paid out of pocket! A generic misfire fault code lumps so many possible issues together without further details. So how can a good mechanic decide on a compression test without swapping plugs + coils first?


      • I think every mechanic would first start with the common things first ignition coils and spark plugs,,,the problem is when it came back the 2nd,3rd and 4th time with the same problem and nobody would look any further.


  7. JC says:

    Morning Andreas!

    Quick question, How are the B-series engines holding up? Any issues unique to these particular engines?


  8. Will says:

    Hey, How’s it going. I have an “issue” I would love to pick your brain about. I have a 2011 BMW 335I Xdrive Build date of 04/10, it has a spun rod bearing. So with the help of some e90post members, I found a mechanic who is a BMW master tech with his own shop. Per his advise I bought an N55 engine with all the bits with it, It is a “New to Me lol” N55 from a 2013 335I that has a build date of 2012-07-09. Come to find out a lot of parts attached to the block have changed from my N55. Is there a way to compare what parts will be different and what will need to be swapped and what CAN’T be swapped?


    • No there is no way to compare on which parts are different,,,besides you are best to swap over your part from your engine to the new engine,,,,lol,,,because you know your parts are good on your engine,,,,I have seen people not swap over parts and they find out the intake manifold is cracked or something else is bad.


  9. Sandiego says:

    Thanks for the very good posting. I was told N55 is one of the most reliable engines on these days BMW. However, the more I see the issues here, the more I think I should be away from BMW. 🙂 My 550i is super nice to drive until it drives but so many issues are killing me. Not only the issues related to the engine but also all the basic issues.


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