I am doing a timing chain job on a 3.0tfsi v6 Audi engine for the first time. Going great but the process of locking the timing has had me a bit worried. The process has been: firstly locked the camshafts both sides and loosened the bolts on both camshaft adjusters. I then was supposed to (after a bit) lock the crankshaft with a pin. After opening the "plug" where you are supposed to insert the locking pin I noticed that the "hole" was not 100% aligned to get the pin all the way in. So with my eye looking inside I had my left hand rotating the crankshaft clockwise and counterclockwise with a maximum of 2-3cm rotation back and forth to perfectly align the hole so the pin could go all the way in. So the question is, have I f**ed the timing now? I’m almost done installing all the new chains and tensioners ):
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Welcome to Motor Vehicle Maintenance & Repair!– Pᴀᴜʟsᴛᴇʀ2 ♦Commented Jul 22 at 13:43
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1 Answer
No, you haven't f'd up anything. If you felt no resistance and were gentle in the procedure, you've done no harm.
The problem with turning the crankshaft is that your engine is an interference engine. The pistons and valves occupy the same space inside the cylinders, except they occupy that space at different times, thus why the timing is important. If the valvetrain is locked in a single position while you turn the crankshaft, you run the risk of running a piston into a valve head. By only turning the crank a small amount, as long as you felt no resistance, there is no issue, because you've not made contact between the two.
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Thank you for the answer. I proceeded with the rest of the job, actually finished up putting all the chains and tensioners in about an hour ago, however when I was going to turn the engine over a few times to check everything after I pulled all the locking hardware, the engine locked up after one revolution, I rotated backwards and it did one more revolution and then after that it wouldn’t budge….i wonder where it went wrong, if I have to reinstall everything? ): I have now rotated the engine backwards to fit the locking hardware one more time ready to do everything again, if that’s the case Commented Jul 22 at 19:10
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@thomshaug - Are you doing the rotating with or without the spark plugs in?– Pᴀᴜʟsᴛᴇʀ2 ♦Commented Jul 22 at 20:10
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@thomshaug Before you come to the logical and probably correct conclusion that the engine is mis-timed, be aware that an engine can also lock up from debris falling into a cylinder. Presumably you took the spark plugs out to make it easier to turn the engine. Any chance something fell into a spark plug hole? A quick peek with a borescope would rule that out. I had an engine lock up from a crumb of carbon that fell in from the intake manifold. It was a diesel with almost no clearance between piston and head.– MTACommented Jul 22 at 20:16
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Yes I have removed the spark plugs so there is no compression. And if debris have fallen inside could be so I have to check but should be a pretty big chunk that would lock up the engine no? What I can’t figure out is why the engine locks up and when turned counterclockwise a bit, it then would rotate a whole new "round" then it locks again. Chain is tight, tensioners work as they should, balancer shaft is not locked up, and camshaft adjuster have the same position both sides. If they have the same as when removed I donno but shouldn’t affect when everything is replaced. Commented Jul 22 at 20:26