991.2 Engine tapping noise after cold start
#46
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#47
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Here is my take.
It appears you will be getting some relief from Porsche. Hope so.
I think you have to look at the landscape here. I mean no disrespect here but, Porsche have created parts changers at best. From the SA to the tech's, they have to log in on any car and tell Porsche what they are doing. Porsche then advises them on what and how to do it. I'm sure there are some very clever people working , but if they are not allowed to think for themselves, what hope do we have.
In this case, I think there was some distance between the noise heard and what is expected to be normal. It seems that once the car was left at the dealer the time and scope of the noise was understood.
I think some good advice has been given and some really bad advice has been given. Do not add any sort of additive in the oil and do not change the oil weight other than what is in the owners manual.
The additive I suspect is some sort of anti wear additive to hopefully stop any wear from happening with excessive lash. First off, this stuff messes with your cat and secondly, a loose lash will not harm the camshaft base or follower. There is a designed amount of gap between the camshaft and the follower for oil to be present.
Oil weight plays a huge role in the engines performance and reliability. With today's mileage standards and emissions, lighter oil is required. Oil pressures are lower to help with performance. It takes a lot of the engines performance to push oil through the system at high pressure. With lower pressures comes tighter oil clearances. The bearing surfaces are rock hard as well for life span. The greatest amount of damage an engine can see from normal use is on startup. You run thicker "winter weight" oil and the oil film between the crankshaft and the bearings will not be there.
Also, the variable valve control is a function of the oils viscosity as well. Changing the oil will effect the valve timing.
A noisy follower is not normal and should never be heard. The oil is trapped in the system once the engine is stopped. The relief valves should close and the oil cannot find it way back. This holds oil in the oil galleys. However the oil has only one path in and out of the follower. The oil galley in the head to feed the follower is on the top side facing upwards. The oil would have to drain up against gravity to escape the follower. Difficult to imagine this happening. And its only way to escape is through the clearance between the follower and the head, which is less than 0.001" on each side.
The follower will collapse the same amount as the cam lift. At this point there is still some head room in the follower before it bottoms out. So oil will always be present in the follower. The cam lobe doesn't squeeze all of the oil out.
You sir have a failing follower that is leaking oil through its retainer sealing system inside that follower. This is happening even when the engine is up to running temps and pressure. The pressure is overcoming the leak, but the leak is allowing the oil to escape through the seal in the follower. This is on the bottom side facing the valve.
This is something of an old wife's tale that followers make noise. Even the dealer appears to be believing this still. The reason is, they don't understand how these engines are designed today as they never get to see inside of them. If they did, they would know its not possible and they would see all of the new ideas used to help with mileage and emissions.
Good luck and demand that the noise in investigated and not left to some old wife's tale. Arm yourself with knowledge. Knowledge trumps a wife's tale every time.
It appears you will be getting some relief from Porsche. Hope so.
I think you have to look at the landscape here. I mean no disrespect here but, Porsche have created parts changers at best. From the SA to the tech's, they have to log in on any car and tell Porsche what they are doing. Porsche then advises them on what and how to do it. I'm sure there are some very clever people working , but if they are not allowed to think for themselves, what hope do we have.
In this case, I think there was some distance between the noise heard and what is expected to be normal. It seems that once the car was left at the dealer the time and scope of the noise was understood.
I think some good advice has been given and some really bad advice has been given. Do not add any sort of additive in the oil and do not change the oil weight other than what is in the owners manual.
The additive I suspect is some sort of anti wear additive to hopefully stop any wear from happening with excessive lash. First off, this stuff messes with your cat and secondly, a loose lash will not harm the camshaft base or follower. There is a designed amount of gap between the camshaft and the follower for oil to be present.
Oil weight plays a huge role in the engines performance and reliability. With today's mileage standards and emissions, lighter oil is required. Oil pressures are lower to help with performance. It takes a lot of the engines performance to push oil through the system at high pressure. With lower pressures comes tighter oil clearances. The bearing surfaces are rock hard as well for life span. The greatest amount of damage an engine can see from normal use is on startup. You run thicker "winter weight" oil and the oil film between the crankshaft and the bearings will not be there.
Also, the variable valve control is a function of the oils viscosity as well. Changing the oil will effect the valve timing.
A noisy follower is not normal and should never be heard. The oil is trapped in the system once the engine is stopped. The relief valves should close and the oil cannot find it way back. This holds oil in the oil galleys. However the oil has only one path in and out of the follower. The oil galley in the head to feed the follower is on the top side facing upwards. The oil would have to drain up against gravity to escape the follower. Difficult to imagine this happening. And its only way to escape is through the clearance between the follower and the head, which is less than 0.001" on each side.
The follower will collapse the same amount as the cam lift. At this point there is still some head room in the follower before it bottoms out. So oil will always be present in the follower. The cam lobe doesn't squeeze all of the oil out.
You sir have a failing follower that is leaking oil through its retainer sealing system inside that follower. This is happening even when the engine is up to running temps and pressure. The pressure is overcoming the leak, but the leak is allowing the oil to escape through the seal in the follower. This is on the bottom side facing the valve.
This is something of an old wife's tale that followers make noise. Even the dealer appears to be believing this still. The reason is, they don't understand how these engines are designed today as they never get to see inside of them. If they did, they would know its not possible and they would see all of the new ideas used to help with mileage and emissions.
Good luck and demand that the noise in investigated and not left to some old wife's tale. Arm yourself with knowledge. Knowledge trumps a wife's tale every time.
#49
While I'm not affected (yet, I don't have my 991.2 C2 just yet) I really enjoyed this excellent description, thanks a lot for this! I have a question though:
How do you diagnose this short of pulling the engine apart?
You sir have a failing follower that is leaking oil through its retainer sealing system inside that follower.
#50
You cannot. But a noise like this warrants investigation and the only way is to disassemble and check. A noise like this could also originate from the chain/tensioner. You have to look and check. My post was more about how noises can be passed off as normal when they are not, if you knew how these engines are designed.
#51
I am having this exact same issue. 991.2 S. Longer it sits, louder the tick (yesterday, it disappeared by the time the motor was at operating temperature, after sitting for maybe 5 days. Interested to hear others experiences.
#53
Addict
Rennlist Member
Rennlist Member
I am having this exact same issue. 991.2 S. It takes about 4-5 days of sitting to get the tapping noise when starting the engine. My noise disappears when the engine warms up to operating temperature. I had it at the dealer on Wednesday to get the recall done for the updated fuel collection pipe bolts and mentioned the tapping. They told me it was not a problem. I told them I wanted to get it "on the record" in case there's a problem in the future. I'm very interested in seeing how this all turns out.
#54
Nordschleife Master
I am having this exact same issue. 991.2 S. It takes about 4-5 days of sitting to get the tapping noise when starting the engine. My noise disappears when the engine warms up to operating temperature. I had it at the dealer on Wednesday to get the recall done for the updated fuel collection pipe bolts and mentioned the tapping. They told me it was not a problem. I told them I wanted to get it "on the record" in case there's a problem in the future. I'm very interested in seeing how this all turns out.
#55
Rennlist Member
Your SO gets cranky when left unattended for too long. So does your 911. Drive it.
#56
RL Community Team
Rennlist Member
Rennlist Member
#59
However the oil has only one path in and out of the follower. The oil galley in the head to feed the follower is on the top side facing upwards. The oil would have to drain up against gravity to escape the follower. Difficult to imagine this happening. And its only way to escape is through the clearance between the follower and the head, which is less than 0.001" on each side..
#60