[DML] Re: carbon deposits in combustion chamber

["Dave Swingle" <swingle@xxxxxxxxxxx>]

That's not the combustion chamber, but the backside of the intake 
valve. The buildup is, unfortunatly, pretty normal since this is a 
CIS (constant injection) engine, so fuel is coming out of the 
injectors all the time. Over time it just builds up carbon on the 
back of the valve. There's no real good way to clean it up short of 
taking the heads off the engine removing the valves. For a while when 
gasoline started having a lot of additives put in, it was fashionable 
(not necessarily on DeLoreans) to remove the intake manifold and 
blast the back of the valves via the intake port with walnut shells, 
but I've not heard of that process for a long time now.

I'd let it be, just going in there and scraping off chunks of carbon 
is likely to cause you more problems than you'll solve. This is one 
of those "they all look like that" things. 

Dave S


--- In dmcnews@xxxxxxxxxxxxxxx, "supermattthehero" <supermatty@xxxx> 
wrote:
> Hello,
> 
> I pulled off my intake manifold last weekend to clean things up, 
and I
> sure am glad that I did.  
> 
> Anyway, getting to the point, when I pulled the fuel injectors, I 
saw
> quite a bit of carbon buildup in the combustion chamber.  I mean, I
> can clearly see a metal rod that goes through each chamber, but the
> bottom of it is really caked up with a hard black material. 




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