Knocking noise from engine

[tbo]

I have a 2003 C2 996 that I took in for servicing / inspection the other day. The diagnosis is that I need a new engine - no other option. I was hoping to get some expert advice on whether this is reasonable or not. Basically I took the car in b/c I of a knocking noise from the engine. They scanned the system for related fault codes and did not find anything. Aside from a few other tests, they eventually removed the spark plugs to check the bore of the cylinders. #4 spark plug was fouled and had deposits. Borescope determined that the sides of the cylinder walls were heavily scored. They determined this cannot be repaired. Can anyone confirm if this conclusion is appropriate?

Thanks in advance for your assistance.

[wvicary]

It could very well be damaged and need replacing. Does their scope capture images that you could post here? Can you describe the type of knocking and did it occur suddenly or over time? How may miles on the vehicle?

[tbo]

The scope captured a short video that was shown to me at the dealer - unfortunately, I do not have a copy of it to post. Generally, it looked like there were several vertical lines on the cylinder bore. I asked if it was possible to have this repaired and they said no... so a big question I have is whether the scores could be machined to repair it?

The vehicle has approximately 50K. The knocking is generally heard when you are idling - and it sounds like a rhythmic putt putt putt putt noise... not sure if that really helps; it is not really a loud or sharp noise, but is definitely noticeable. It's hard to recall, but I think it started several months ago - but at the time it didn't seem that bad... I actually thought it was coming from the muffler. I just happened to be at the service center the other day and asked a mechanic to listen to the noise for me, resulting in this diagnosis.

What I'd really like to get a handle on is whether this can be repaired - which would be much cheaper than buying a new engine. The shop said as soon as they saw the scored lines, it is beyond repair.

[Dharn55]

Take a look at resleeving the engine by LN Engineering, about $4.000 with new pistons and rings. This does not include disassembly and reassembly.

http://www.lnengineering.com/boxster.html

[txhokie4life]

I tore down a 3.4L that had a spun bearing -- it too had the scoring on the walls and pistons.

you could see where the piston was hitting the cylinder head. Ultimately causing a head gasket failure and intermix.

this block cannot be repaired short of relining.

I never heard this 3.4 when it was running -- but I suspect it would have sounded like what you described.

the spun bearing allowed the connecting rod to have more play and piston slap.

mike

[RFM]

It's a sort of tapping noise, a little more pronounced than a valve lifter. Some Cayenne V8 owners known the noise and the result very well.

[tbo]

I tore down a 3.4L that had a spun bearing -- it too had the scoring on the walls and pistons.

you could see where the piston was hitting the cylinder head. Ultimately causing a head gasket failure and intermix.

this block cannot be repaired short of relining.

I never heard this 3.4 when it was running -- but I suspect it would have sounded like what you described.

the spun bearing allowed the connecting rod to have more play and piston slap.

mike

Ok got it. Anyone have comments on whether "nikasil" or "alusil" would work?

Thanks for your patience.

Edited February 26, 2010 by tbo

[wvicary]

What part of the country are you located in??