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  1. #1
    Established Member Two Rings sQ5inSD's Avatar
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    Apr 26 2020
    AZ Member #
    546264
    Location
    Las Cruces, NM

    3.0T CTUC partial teardown - solutions looking for problems!

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    Preamble: 2013 Q5 at 149k miles now, purchased bone stock in 2020 at 95k miles. Mods: 034M stage 2 (91 octane) with 187mm crank pulley, IE intake and Merc HX. Stock exhaust and cats. Typical service history under my ownership including PCV (latest rev VAG-06E103547AH) coolant pump/thermostat, plugs/coilpacks, all fluids and filters, belts, etc. Carbon clean intake valves at about 125k miles. Failed a serp belt tensioner around 135k miles (January of 2023) so I pulled the crank pulley and inspected the front crank seal which looked fine. One month later I noticed a "greyish" smoke exiting the rear mufflers on startup, not white not blue. Life got in the way and I did not determine or fix the cause of the smoke on startup, it does not always smoke on startup nor after running at normal operating temps - cold starts after a few days sitting make the most smoke. A few weeks ago the motor began misfiring badly. I pulled the plugs and found them totally fouled with wet carbon. After replacing the misfires did not change at all so I said F#$@ It! and began pulling the motor. The pics show what I found and it does not look good to me...

    So I need advice on what next steps to take. I have on hand new head gaskets/bolts as well as a complete VAG timing service kit. I plan to find a shop that can flush/test the fuel injectors or I will replace them if necessary. I have a reasonable cost source for new piston rings and valves if needed. I intend to do as much of the labor as possible. Other than decarbonizing and reassembling the motor what else needs to be done? Is there any way to prevent or reduce the carbon returning? What about oil on the injectors/plugs? I want to keep this Q and make it reliable again!

    heads_valves.jpg

    bore score.jpg

    injectors.jpg

    valves.jpg

    added pics of the valves removed from the head to show the condition before cleaning
    Attached Images
    Last edited by sQ5inSD; 11-03-2024 at 10:00 AM.

  2. #2
    Junior Member Two Rings
    Join Date
    May 24 2024
    AZ Member #
    987740
    Location
    South Texas

    Quote Originally Posted by sQ5inSD View Post
    Other than decarbonizing and reassembling the motor what else needs to be done? Is there any way to prevent or reduce the carbon returning? What about oil on the injectors/plugs? I want to keep this Q and make it reliable again!

    heads_valves.jpg

    bore score.jpg

    injectors.jpg
    You could research the pcv relocation kit and or oil catch can. for many years it was believed that multiport injection / CREC engine would eliminate carbonbuildup,but as far as i know none of the above will entirely eliminate carbon buildup.

    IMO it would be self-ownage / self-trolling of the highest degree if putting in 11 year old /135k mile injectors caused another major failure...
    Have you e-mailed 034 for advice on the topic? they answered someone's injector related question in today's live stream episode not sure if that might've been you.
    I am a 034 nutswinger
    Disclaimer: I am not sponsored or affiliated with 034 motorsport, just one of many happy customers.

  3. #3
    Established Member Two Rings sQ5inSD's Avatar
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    Apr 26 2020
    AZ Member #
    546264
    Location
    Las Cruces, NM

    thanks for the reply - a couple of others have also suggested the relocation/catchcan option, I am not sure but willing to try that if it resolves the problem - no it was not me, I have not contacted 034M about any of this but despite my less-than-ideal history with them I probably should!

    I will do some research about getting the injectors tested simply because the OE/OEM versions are too $ to just toss out and if it does turn out one or more are bad then at least I will know what has been contributing to the problems.

    what I need to decide on soon is how much further to teardown the block if the piston rings need to be replaced - I am planning to clean and refurbish/upgrade the valvetrain regardless, maybe a set of titanium springs

  4. #4
    Senior Member Four Rings
    Join Date
    Dec 01 2020
    AZ Member #
    575541
    Location
    2014 Q5 2.0T

    That cylinder bore looks scored. Does a fingernail catch when you run it across that section of the bore?

  5. #5
    Established Member Two Rings sQ5inSD's Avatar
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    Apr 26 2020
    AZ Member #
    546264
    Location
    Las Cruces, NM

    actually no it does not - the bores feel really smooth

  6. #6
    Senior Member Four Rings
    Join Date
    Dec 01 2020
    AZ Member #
    575541
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    2014 Q5 2.0T

    You should be ok then

  7. #7
    Established Member Two Rings sQ5inSD's Avatar
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    Apr 26 2020
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    Location
    Las Cruces, NM

    I hope so but I am still considering going all the way and pulling pistons to inspect the rings - for now I have the valves out of each head and they all look like just cleaning will be enough to restore them plus maybe new stem seals just because it is all apart now

  8. #8
    Senior Member Four Rings
    Join Date
    Dec 01 2020
    AZ Member #
    575541
    Location
    2014 Q5 2.0T

    How much oil was it burning? If you have it this far I definitely would pull the pistons to inspect the rings, especially if it was burning oil...

  9. #9
    Established Member Two Rings sQ5inSD's Avatar
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    Apr 26 2020
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    546264
    Location
    Las Cruces, NM

    that is hard one to answer because the upper timing chain covers both had bad leaks and then the front main crank seal was apparently compromised - probably from when the serp belt failed - include a suspicious PCV so overall just before I yanked the motor out it was a quart every 300 miles

    forgot to mention when the supercharger lifted off there was motor oil in that weird offset vent tube between the bottom of the SC and the top of the PCV so I also plan to pull the bricks and inspect the interior of the SC

  10. #10
    Senior Member Four Rings
    Join Date
    Dec 01 2020
    AZ Member #
    575541
    Location
    2014 Q5 2.0T

    At a quart every 300 miles seems very likely there was oil consumption, since you are this far in I would def pull the pistons to inspect the oil control rings and see if they are clogged with carbon.

  11. #11
    Established Member Two Rings sQ5inSD's Avatar
    Join Date
    Apr 26 2020
    AZ Member #
    546264
    Location
    Las Cruces, NM

    that is my next move - just need to finish removing the lower timing chains and pick up an engine stand at Harbor Freight Racing

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