Dick964

Last time I did a valve-clearance job, sparkplug change, oil change etc. etc.
I found 3 small pieces of ceramic origin in catalysator...

I did some research on all the well known forums about this and I found out that it often happens that the ceramic innerliner of the exhaust ports can come off. What I didn't find was a good answer about how bad this is...

So what is your opinion ? Can it harm the engine ? Will it run hotter ? What is your experience with this 'problem' ? Is it the start of more problems in the nearby future ? Will more ceramic particles come off ?

My car is a 1991 Carrera 2 Tiptronic with only 61.000 miles on it...

Hope some of the technicians can answer this

Thanks to all,

dick964

chancecasey

I'm no expert - but many that I've talked to say don't sweat it. The 964 was the first production Porsche head incorporating ceramic liners if I'm not mistaken - so long as the bits never get sucked into the cylinder, they are harmless going downstream. The performance effect of the missing ceramic is pretty negligable.

Geoffrey

It certainly affects the port flow and hence the exhaust scavaging.

pete000

I think the Porsche tech article publishes that if the chunks are smaller than a certian size not to worry. I can't remember the exact size. I found some small chunks in my Cat when I had it off. I think most every one does...

JasonAndreas

Cylinder Head Ceramic Liners - Cracks or Breaks

June 8, 1990

Model
911C2/C4

Group
1

Number
9015

Part Identifier
1570

Subject:
Cylinder Head Ceramic Liners


ATTENTION:
Service Manager/Service Technician

Models Affected:
911 Carrera 2 and 911 Carrera 4

Concern:
Cracks or breaks in ceramic exhaust port liners.

Repair Information:
Small cracks and/or breaks in the ceramic port liners in the area of the valve guides are sometimes visible even on new cylinder heads (See Figure 1). They do not influence the function of the port liners.

Cylinder heads must not be replaced for the above mentioned symptoms unless 1) breaks go down to the base material of the cylinder head, 2) broken surface area is larger than 1 sq.cm (0.155 sq.in.) or 3) the cracks extend from valve guide to the edge of the ceramic liner (on the valve seat or exhaust flange area).

Dick964

Hmmm, I have not seen my exhaust ports (yet...) but if I understand the tech article right, one should have to worry a bit about particles...

Is there anyone who knows of a failed engine due to the absence of the ceramic liner ??

Thanks,

Dick964

Chris Martin

Here's an example

http://muvvachicken.com/images/porsc...mage013_sm.jpg

Dick964

OK Chris,

Thanks for the picture.... It doesn't seem that harmfull to me... I will take off the complete exhaust this winter to see how bad it is in my engine.


gr.

Dick964