Stuck Rings
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From: Wyoming
Stuck Rings
Hi all. I have a '12 Q5 2.0T with 198k. I had it in the shop and was told there is a loss of compression on two cylinders (after he de -carboned it). He said the rings were stuck, and blamed it on whoever did the piston/ring job over 120k+ miles before. My brother thought it might be carbon build up, and suggested putting marvel mystery oil in the cylinders and letting it set a few days. Then I was to remove fuel relay and spark plugs and crank the engine to blow the crap out of the cylinders. Problem is, it won't crank at all with the plugs and coils out. He's done this with other vehicles and the starter cranked the engine, but it's not working in the Q5. Any thoughts on why this is? Is there some safety thing that won't allow it? (Please don't tell me it won't start without plugs. I don't want it to start.) 😉 Thanks in advance! BTW, I'm in the middle of Wyoming. There are no dealerships here.
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What is the marvel mystery oil that was used?
I would use a fluid extractor and remove any liquid from the cylinders. I would also blow out the cylinders with compressed air with a rag over the spark plug hole to remove the dregs. Then put it back together and start it. Ideally each cylinder should be filled to the spark plug hole with something like Berryman B12 and allowed to soak while each one is at TDC to ensure all valves are closed, as this also cleans the entire combustion chamber including the valve heads on a 2.0T.
I would use a fluid extractor and remove any liquid from the cylinders. I would also blow out the cylinders with compressed air with a rag over the spark plug hole to remove the dregs. Then put it back together and start it. Ideally each cylinder should be filled to the spark plug hole with something like Berryman B12 and allowed to soak while each one is at TDC to ensure all valves are closed, as this also cleans the entire combustion chamber including the valve heads on a 2.0T.
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From: Wyoming
AudiAllTheWay, Marvel Mystery Oil is supposed to break down carbon and sludge in the system. So, the idea is, if the rings are stuck due to carbon build up, it might help. I'm not sure what the mechanic used when he de-carbed the head. It may have been the B-12 you mentioned. He didn't say. At any rate, this is a last ditch effort to improve the compression in the two cylinders that were low.
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From: Jurupa Valley, California
These cars don't have a fuel pump relay so if you removed a relay then that relay is for something else. As long as it is authorized to start (key recognized by the car, transmission interlock ok), if the start button is pressed (or the key is pushed in), the starter will be energized. It doesn't matter if the coils are connected or not.
Last edited by alex_hobeanu; Sep 20, 2024 at 12:56 AM.
AudiWorld Member
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What is the marvel mystery oil that was used?
I would use a fluid extractor and remove any liquid from the cylinders. I would also blow out the cylinders with compressed air with a rag over the spark plug hole to remove the dregs. Then put it back together and start it. Ideally each cylinder should be filled to the spark plug hole with something like Berryman B12 and allowed to soak while each one is at TDC to ensure all valves are closed, as this also cleans the entire combustion chamber including the valve heads on a 2.0T.
I would use a fluid extractor and remove any liquid from the cylinders. I would also blow out the cylinders with compressed air with a rag over the spark plug hole to remove the dregs. Then put it back together and start it. Ideally each cylinder should be filled to the spark plug hole with something like Berryman B12 and allowed to soak while each one is at TDC to ensure all valves are closed, as this also cleans the entire combustion chamber including the valve heads on a 2.0T.
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Joined: Jan 2005
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AudiAllTheWay, Marvel Mystery Oil is supposed to break down carbon and sludge in the system. So, the idea is, if the rings are stuck due to carbon build up, it might help. I'm not sure what the mechanic used when he de-carbed the head. It may have been the B-12 you mentioned. He didn't say. At any rate, this is a last ditch effort to improve the compression in the two cylinders that were low.
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AudiWorld Newcomer
Joined: Sep 2024
Posts: 3
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From: Wyoming
These cars don't have a fuel pump relay so if you removed a relay then that relay is for something else. As long as it is authorized to start (key recognized by the car, transmission interlock ok), if the start button is pressed (or the key is pushed in), the starter will be energized. It doesn't matter if the coils are connected or not.
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