Porsche 996 Ticking Sound on Idle

[JD911]

Hi Guys can you help please - I have a 996 2001 C4 (96k) its just had a major service and I am hearing a ticking sound on idle coming from the rear drivers side . I thought it was a spark plug issue and some say tappets .

I took it to Porsche today and they told me it was " Engine Noise Traced to cracked Liner on Cylinders 5/6 Will require a strip to determine fault " = 3100 Pounds to strip excluding parts to fix which he said could come up to 6k. They told me they traced the noise using a stethoscope and bore inspection but they also said 9/10 its a cracked liner . If they did a bore Inspection dont you think they would have said 100% cracked liner ? Also they only had the car for 45 mins

If it was this shouldn't there be oil and water and smoke coming out of the exhaust ? I am getting none of this and I only get a ticking noise which has has been present for 2 weeks now

All i am getting is a ticking sound on idle which goes away at 1800 revs and no power loss or oil pressure drop at all . Car drives fine just on idle is ticks .

The noise is EXACTLY the same as this I found on youtube

https://www.youtube.com/watch?v=D5byxowZb3s

Any Ideas guys ? or do you think Porsche are pulling a quick one on me ?

[hartech]

If you research ticking noises on various forums you will find it is usually something that is a sign of an older car and comes from a variety of sources - usually none of which are a sign of any mechanical problem.

If the noise is from a scored bore and is the piston tilting and touching the cylinder head then there will be higher oil consumption and a darker LHS exhaust pipe to go with it and a boroscope will reveal bore scoring.

It can be caused by an old tappet, and a variety of other components resulting in a slightly uneven tickover causing the cam chain to snatch.

Usually it cannot be got rid of without a full engine strip and even then some cars retain the noise after a rebuild.

I would avoid paying for a full strip that would lock you into an outcome of perhaps a new or expensively rebuilt engine with no other benefits or improvements.

Possibly get an independent to give their opinion (providing they are used to the subject and remedies etc).

Baz

[Rockster]

Who did the service? What was done?

Was the right oil used? Is the oil level good?

If the noise appeared after the service it is less likely to be something internal and more likely to be something external. I dare say more engine ticks have been due to a loose spark plug or a leaking exhaust than a cracked liner.

That you have used the car for 2 weeks and the noise hasn't gotten worse, that no other symptoms have appeared, the coolant level has remained constant along with the oil level, I'd say the noise is not an internal problem.

While I'm reluctant to go against the diagnosis of a tech, my money would be on a loose plug.

The Porsche dealer is probably doing like my doctor does when I visit him with a complaint. He tells me it could by this, or it could be that, and everything is terminal, but after the tests come back I'm told to exercise more, eat less, and get more sleep.

I would be inclined to take the car back to where you had it serviced and have it checked for a loose plug. Although, if I suspected the shop left a plug loose I'd be of two minds whether to return to that shop or seek another shop. I'd rather eat the cost of having the plugs checked than risk having the car back in the hands of the shop that left a plug loose. It might not bother to check for a plug and this could have you go on an expensive repair job for nothing.

If no plugs are found loose, if an inspection of the exhaust finds no leaks, then the noise can be something internal. It might then be worth it to have an oil sample taken and sent out for analysis. This will look for various things including the presence of anti-freeze compounds in the oil. If these are found, then a cracked cylinder becomes a more likely explanation.

[Pope]

Inspection has taken place - with a boroscope; suggesting the plugs, if they were loose, would now be tight again.

As Baz says it could be multitude of other things and or the liner/bore.

I have seen tappets wear through causing similar noises; but any internal noise will unfortunately require an amount of stripping and investigation to ascertain the noise source.

The boroscope would likely have a picture/video storage device - mine has - were you shown the results of the boroscope test??

[JD911]

Hi Guys thanks Hartech and BAz for replying.

So my Friend did the service but not an ordinary friend hes been a Porsche mechanic for 15 years :-)and he suspects a tappet but needs to look further so think a slightly thicker oil might do the job to get rid of the ticking sound . I took it to Porsche as hes busy for a few weeks and cant look at it .

I just got back from work and drove it hard with absolutely no lose in performance. idle is just under 2 bar and when at cruise 4ish -5 . At idle a few mm of fluctuation but nothing major which should result in the engine itself being good right ?

Porsche had the car for 45 mins I dont think its long enough for them to have taken the spark plugs out / found out which cylinder the noise was coming from and also to do a bore inspection like they said they did . I Hope all they did was link it to the computer and computer said 5/6 cylinder missing therefore lets get him to pay for a rebuild ??

[JD911]

Hi Pope no video evidence - Im an IT Director ; obviously if anything when we do a troubleshoot and have to show the client we do snap shots :-(

I shall call them tomorrow and ask them that at West London Porsche ;-)

I never thought of that !!!! and then they tell me its 9/10 its cylinder lining crack

Like I said if they saw it then its certain ! ufffffff

I have never posted on a Forum before but im so happy I did with the response i have so far

Thanks Guys !