"Stephen Young1" wrote: > shiden_kai wrote: > > NickHanson wrote: > > > > > >>I have a 1997 GMC pickup with the 5.7L V-8 Vortek > engine. The problem > >>I have is that it has a bad miss/shudder down the road > and rough idle. > >>I recently pulled all the plugs to check the condition > and see if > >>there was anything unusual. The spark plug on the #6 > cylinder is > >>covered with carbon. I also noticed that I have been > lossing a little > >>bit of anti-freez, about a half gallon every few > months. I think I > >>may have a burned valve on the #6 cylinder?? Also > maybe a leaky > >>intake gasket possibly both on the front and rear. > Any ifon that > >>anybody may have would be great or any ideas as to > weather my > >>diagnosis is correct on the burned valve. Thank you > very much > > > > > > The first thing I would do is get the intake gasket > replaced. Not > > only do they leak antifreeze on these engines, but I've seen > a number > > of them get distorted and they will go out of shape and > develop > > a vacuum leak at a cylinder or two. The vacuum leak will be > inside > > the engine, so spraying stuff around the exterior of the > intake will > > not find the leak. Anyway, if you are using antifreeze, the > gasket > > needs to be replaced. I'd do that first and then see how > she runs, > > she may smarten right up. > > > > Ian > > > > > While you have the intake manifold off, do a thorough cleaning > of the EGR valve & passages - > mine had 100% blocked passages which, when cleaned, smoothed > the motor immensely.
Thanks for the suggestions. I will do the manifold gasket first and do a good cleaning inside when I have apart. But I can?t see that causeing #6 spark plug to be covered with Carbon?? Maybe I am wrong but I think there are further problems. Last night I unplugged my mass airflow sensor and it did not take the roughness away but did give me all my power back and improved my gas milage quite a bit too. Anything else you guys can think of would be great!!
Thank you
Nick Hanson