fsi / carbon buildup

[John Larson]

On 6/6/2014 12:50 PM, Huw Powell wrote:
> Look up VW intake manifold cleaning on Youtube, they use a propane 
> torch and compressed air to burn it out.  Very cool to watch the eight 
> foot flames...
>
> On 6/6/2014 11:40 AM, thejimrose wrote:
>> ...it's probably mostly there to stay,
>> until it's forcibly removed a la media blasting and dental picks...
>
My comments are based on carbon buildup on the intake valve stems, not 
the intake manifold, which is a "diesel thing".  While a PITA as well, 
it's a whole different thing, and the build up is a nasty semi-slimy 
accumulation of passage filling carbon goo caused by exhaust gas 
recirculation, not hardened carbon on the valve heads and stems.  I've 
done the diesel manifolds, and they're no picnic, but you don't have to 
watch what falls into the engine.  BTW, I've seen a case where bits of 
carbon have fallen off a valve and gotten caught between the valve and 
the seat.  Those valves are mighty tiny, and they bend REALLY easily.

John