3.0T CTUC partial teardown - solutions looking for problems!

[sQ5inSD]

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!

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added pics of the valves removed from the head to show the condition before cleaning

[STXA7]

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!

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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.

[sQ5inSD]

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

[silver_tt]

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

[sQ5inSD]

actually no it does not - the bores feel really smooth

[silver_tt]

You should be ok then

[sQ5inSD]

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

[silver_tt]

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...

[sQ5inSD]

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

[silver_tt]

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.

[sQ5inSD]

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

[hahnmgh63]

Did you do a leakdown/troubleshooting test before pulling it apart to try to determine what leaked the most, Rings or Valves? Hard to tell from the pics but the valves/seats don't look too bad, how are the guides? Obviously new guides and stem seals will help with some of the Oil but how much depends on how bad they were and how much is getting by the rings. As Silver_tt said, if that one cylinder scrape is the worst, and you really don't feel it with a fingernail then the rings are probably most likely pretty good shape for at 150k motor. Probably won't go another 150k without more work but maybe 100k. Do you have the lower and upper oil pan sump off the bottom? If so I'd pull a Rod cap towards the back and check the connecting rod bearings, they tend to go before a main bearing. May want to throw in a set of Rod bearings and new rod bolts. All of the Supercharged 3.0t's use the same versions of the Rod bearingshttps://kingenginebuilders.com/cr6882sv , color codes are stamped on the Block but you can get the King Rod bearings which cover the range for around $125, Rod bolts are only $1.43 each, unusually cheap https://www.buyaudivwparts.com/oem-p...-wht003466audi

[sQ5inSD]

Good question on the leakdown test - I did one back when the motor was blowing smoke after the serp belt failure (see the Preamble at the start of this post) and at that time the results were good (90 psi into each cylinder holding 85 PSI) but recently I did not do that test again becasue I had just decided the motor was going to be out for fixing the oil leaks - yes, that was impulsive but I am far enough into the teardown now and looking forward to fixing as much as possible while it is out.

I just got a Harbor Freight Racing engine stand so now the block is on it and I will pull the bottom off this week so stay tuned...

[sQ5inSD]

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pulled one of the pistons closeest to the rear main - looks like the bottom ring is bad but all else looks good - probably going to do the rings and rod bearings on all six just because I am this far in and it is only time/$ after all

[silver_tt]

Yep that oil control ring is toast. Same style rings as the 2.0T and looks just like mine that I pulled out a month or two ago. I would replace the pistons... on the 2.0T the piston replacements were slightly larger and all 3 rings were completely different. I would also look at the timing chains while you are in there, the 3.0T can stretch chains just like the 2.0T.

[sQ5inSD]

ok thank you for the info - I have a source for reasonably priced OEM rings (RockAuto as well as UROtuning) and con rod bolts but OE VAG rod bearings are $$$ so after I pull the other pistons I will post pics - not trying to be cheap but why do you say new pistons now?

I have a full OEM timing service kit - when I pulled the rear covers off everything looked like new, there were no broken guides and none of the tensioners were at their limit, all the cam gears were aligned with the timing windows as well - prior to tearing down the motor I was able to lock both sets of cams and install the crank locking pin so that tells me the motor was good in that regard

thanks again for the feedback from all members so far - this is as far into a motor as I have ever been in 30+ years of VAG cars and dang did I pick the right one to learn on

[silver_tt]

I bought all my parts from Audi. I bought the rod bearings but returned them because upon visual inspection they looked great (I change my oil frequently).

I said consider new pistons for a few reasons. At least on the 2.0T the new OE pistons are slightly larger -- not sure about the 3.0T but seems feasible. Further the new OE pistons come ringed and it will be difficult to completely clean the ring lands your old pistons (maybe you can dip them in B12 for a week I don't know) which would inhibit the new rings from functioning completely properly.

[sQ5inSD]

I did soak the pistons in B12 for a few days but do not plan on replacing them unless that is the only way - I am not seeing any info stating this needs to be done on a motor given my situation but I am still in research mode now

CRANK_SPECS.pngPISTON_SPECS.png

trying to gather info for having a machine shop measure for wear limits and sizing new bearings - these are from the shop docs on ERWIN - does anyone have any more/better info?

UPDATE: got busy with work and travel during Thanksgiving to see my 19 yr old son graduate from USMC boot camp on Parris Island - finally had a chance to "interview" a local machine shop and was told by the shop owner German motors have loose valve guide tolerances so their cylinder head services include replacing all the guides - that rang bell in my mind so I went back to the repair docs and found this:

VALVE_SPECS.png

Can anyone confirm this note about the valve guides not being replaceable - I will try a couple other machine shops and see what they have to say so stay tuned...

[sQ5inSD]

Did you do a leakdown/troubleshooting test before pulling it apart to try to determine what leaked the most, Rings or Valves? Hard to tell from the pics but the valves/seats don't look too bad, how are the guides? Obviously new guides and stem seals will help with some of the Oil but how much depends on how bad they were and how much is getting by the rings. As Silver_tt said, if that one cylinder scrape is the worst, and you really don't feel it with a fingernail then the rings are probably most likely pretty good shape for at 150k motor. Probably won't go another 150k without more work but maybe 100k. Do you have the lower and upper oil pan sump off the bottom? If so I'd pull a Rod cap towards the back and check the connecting rod bearings, they tend to go before a main bearing. May want to throw in a set of Rod bearings and new rod bolts. All of the Supercharged 3.0t's use the same versions of the Rod bearingshttps://kingenginebuilders.com/cr6882sv , color codes are stamped on the Block but you can get the King Rod bearings which cover the range for around $125, Rod bolts are only $1.43 each, unusually cheap https://www.buyaudivwparts.com/oem-p...-wht003466audi

I did finally reach out to Kings but they told me they do not offer any bearings for this motor

[sQ5inSD]

I also contacted AMTuned in Florida - they offered to sell me piston rings but said no to any of the bearings.

[sQ5inSD]

small update - got the OE fuel injectors back, all cleaned and flow tested with new teflon tip seals and shipping for $250 turns out two of the six were not spraying any fuel and the other four were all not operating correctly but after cleaning they are all like new again!

[sQ5inSD]

has anyone had any luck sourcing OE or high(er) quality aftermarket main and rod bearings? Audi dealers that have them in stock are charging outrageous prices compared to what aftermarket vendors offer for other VAG motors - the problem these vendors do not have an application for the 3.0T so far I have reached out to King, VAC/Milano and ACL - none offer bearings. Any info helps - what are folks using?