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The camshaft has to turn and should just like the other side does. I'd say you either have a broken timing chain or the cam sprocket to camshaft bolts have sheared off so the sprocket is turning but it's no longer connected to the camshaft. Neither of these scenarios are good so I hope it's something else that I haven't thought of.
Originally Posted by ekstroemtj
Thank you for taking the time explaining your story in detail. In the end you are lucky. It could be much much worse.
Maybe it is much worse than it looks like already. As @theprf said above "there will be bent valves" as it is an interference engine. One mechanic suggested that I could perhaps get away with a replacement of the broken chain and the sprocket set. But the other mechanic was not very optimistic. He said there will be bent valves and repairing them will cost almost same as a new engine. He suggested I would not even try to spend money on the chain replacement. At this moment I might be suffering from the "sunk cost fallacy" as I was preparing the order the chain set. Then this bro saved me:
Thank you HumbleMechanic! You illustrate exactly what happens when the chain gets broken.
So just to rephrase, if your engine light comes on you start to have start issues. Stop there right now. Check the error code; if it is camshaft error. Call a truck to tow it away, if the chain is not yet broken, you might still have luck to save the engine.
Otherwise try to digest the following ---> timing chain broke = engine replacement.
I would pull the cams and then do a leakdown test on each cylinder. If you don't have excessive leakage, then proceed with the chain swap. If you have excessive leakage, probably time to start shopping for a new engine. Given you have a 2008 and they can have bore scoring issues, I'd try to find a good engine from a 2010. Good luck!
I would pull the cams and then do a leakdown test on each cylinder. If you don't have excessive leakage, then proceed with the chain swap. If you have excessive leakage, probably time to start shopping for a new engine. Given you have a 2008 and they can have bore scoring issues, I'd try to find a good engine from a 2010. Good luck!
Wow that sounds like a good idea. Can you point me out how I could do this leak down test on the cylinders?
Does it require me to strip off further parts?
I would not spend a nickel on it other than for a good replacement long block engine myself. If it were mine, I could pull the cams with just my labor and I might do that. Paying a shop to mess around with an engine that was driven with a serious fault until it would no longer start is probably not a wise spend.
It might be cheaper to borescope and look for indications of piston to valve contact.
Wow that sounds like a good idea. Can you point me out how I could do this leak down test on the cylinders?
Does it require me to strip off further parts?
Here in the States, you can rent (with a refundable deposit) a cylinder leak down tool kit from local auto parts stores. You'd also need an air compressor. If you can get a leak down kit (especially for free), and you already have an air compressor, then it would be worth you doing the leak down test yourself. Ideally, you would be able to rotate the engine to top dead center (TDC) for each cylinder to perform the leak down test, but, since you have a timing chain issue, pulling the cams is the only way. Once the cams are removed the valves will all be closed (or hopefully!) and the leak down test should at least show if you have any badly leaking cylinders. With the cams removed and the valves supposedly closed, no air should be escaping through the intake or exhaust except for the permissible amount that passes the rings.
If you have to pay someone or buy tools to do the leak down test, maybe try Jfrahm's suggestion of buying a borescope and looking for piston damage. However, I worry that it may be inconclusive. You should be able to pick up a borescope for under $100 USD and it's a good tool to have anyways.
Thank you @BobcatBrian and @Jfrahm for the gold advice. My friend has a setup for small repairs, he has the compressor and all. He has the borescope but not the cylinder leak kit.
We can just inspect the valves with the borescope to start with. Is removing the camshaft a complicated affair?
We'll check the valves tomorrow morning. I'll post the pictures for future reference. Thank you for the continued support.
I haven't removed the cams from a Cayenne, but I have read that the cam gear bolts are difficult to remove due to their high torque values during installation.
I haven't removed the cams from a Cayenne, but I have read that the cam gear bolts are difficult to remove due to their high torque values during installation.
This is true, however if the timing chain is actually broken the cams should be removable with the gears installed.
Do be careful of the trigger wheel on the back of the intake cam. It's fragile and easy to break.
This is true, however if the timing chain is actually broken the cams should be removable with the gears installed.
Do be careful of the trigger wheel on the back of the intake cam. It's fragile and easy to break.
Ah, that’s a good point. I wasn’t sure if the the cam gears needed to be removed for clearance. But if not, that makes it pretty easy. And good call on the trigger wheel too.
Yes. A trustable mechanic advised me to just replace the chain (set) and check how the engine is doing before buying a complete engine. This is relatively quick and cheap as I could find cheap OEM sets (which are actually compatible with VW, Audi, BMW). I have ordered the parts and waiting. He reckons, since the chain got broke during start up, the damage could be somewhat minimal.
He tells me that this issue is very common in these engines and the culprit is "the tensioner" not the guides or the chain. He says this thing malfunctions and the chain gets loose. The loose chain hits the guides and breaks them. When operating with the loose chain it bounces and snaps inside the cover and at some point it breaks. He says you need to change it every 100Kmiles or so. The replacement of the tensioner is very easy and cheap. But the problem it causes will be huge once it malfunctions.
He also tells me, if my engine is FUBAR, that I don't have to buy a 2008 engine, which costs around 5K.Seems I could just buy the previous generation 2007 engine and he could put my 2008 engine parts to the new 2007 engine block. He says the block is the same. This is interesting as the pre-2008 engines are half the price of a 2008 engine.
Anyhow, at this moment we need to change the complete chain set, including the tensioner, guides, chain etc. because the snapped chain broke them all.
I will post an update after we change the chain set.
I hope he takes you out on his boat, given that you're making the next few payments.
haha the guy just bought a hotel, he says he wants to get out of the garage business. He said he would change the chain set for free. (I would need to prepare the car for him tho). Well he is a good friend of a good friend. Sure I will need to reciprocate the favor. (I was in the hotel business before). I'd prefer the fussy engines to fussy hotel guests any day.
I hope the new chain fixes it. BTW, the 4.5L and 4.8L are not the same. The bore is different and you have direct injection. If you need a new engine, you’re stuck with the 4.8L
10-13-2023, 08:48 AM
as I was preparing the order the chain set. Then this bro saved me: 
