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I noticed that sometimes when I crank my truck blue smoke comes out of the exhaust. Does anyone know what this means. I know that my oil needs to be changed. Would that be the only thing to cause this...thanks
Yeah, that is probably correct. GM 350 engines are notorious for doing this. I believe we installed new valve guide seals on my old Chevy truck in one Saturday morning. Just requires a couple of special tools which are usually available at local autoparts stores.
There not bad to do but you will need an adapter to apply air pressure to the cylinder to hold the valves up and a valve spring compressor. You remove the valve covers and anything else to get them off, remove the rockers, then the springs and then replace the seals.
My understanding is that the valve seals are the pieces of rubber that the valves stick through down into the cylinder. Since there is oil up by the camshaft and the top of the valves, and the bottom of the valves are in the intake/exhaust path, if your seals are leaking then oil will get down into the cylinder and hence you will be burning oil.
The seals look like little umbrellas fitted over the valve stem, the valve stem is what comes up out of the head. The seals only limit the amount of oil that is allow to get on the valve stem, it does require some oil. When the seals go bad you get to much oil on the valve stems and it works it's way down into the intake. It builds up after you shut the engine vs getting burned slowly when it's running, thats why you notice more when you first start the engine after its been sitting.
Hey jhdaniels, which engine & year do you have?? The 2.8 V6 was notorious for doing this. Mine does it. They had neoprene seals, which don't hold up a long time. If you decide to do the job, try to get high quality seals, like DuPont Viton, or similar.