|
|
|
|
| Author |
|
|
Registered
Join Date: Mar 2006
Location: sweden
Posts: 39
|
Why is cylinder 2 and 5 black?
Hi
I did a top-end rebuild 2009. 3.0 SC engine. All head was restoration and now when i look at heads again i see that cylinder 2 and 5 are running rich. This time i check all valve for leak, because a over rev and cylinder 2 and 5 was not perfect. I didn't do that check 2008 because i thought the shop was professional. Could that be the reason that cylinder 2 and 5 are black (running rich)? Picture below is a sample on bad and good head.   Regards tom
__________________
/tom 911 sc -83 944 -86 KTM 125cc Last edited by tom.langborg; 06-11-2012 at 10:42 AM.. |
||
06-11-2012, 10:33 AM
|
|
|
Registered
Join Date: May 2003
Posts: 3,346
|
That doesn't look bad to me. There is very little carbon in the ports. That blob of carbon is from oil, not from running rich. Just a little oil is leaking in through the valve guide. Don't worry about it.
-Andy
__________________
72 Carrera RS replica, Spec 911 racer |
||
|
06-12-2012, 10:37 AM
|
|
|
Senior Advisor
|
exhaust valves have the worst job in an engine, they get the hottest, operate at the highest pressure, move very fast, metal to metal contact, and must be lubricated. i don't thing that any engine has prefect valve guides. As Andy says, don't worry about it, drive!!
__________________
08 Cayenne Turbo |
||
|
06-12-2012, 12:49 PM
|
|
