Hey guys, My engine is burning some oil and am confident that I have bad valve seals. (The engine is recently rebuilt with only 3000 miles or so). So I am wondering if I can Change the seals with the heads on the engine. I know I can get off the rockers and springs fine, but i am worried about the valve. If i take the spring and the retainer off can the valve slide down through the valve guide and into the cylinder and not be retrievable? If so is there a way to hold the valve so it does not slide down when I change out the seals??? Thanks!
You need a good continous supply of compressed air to pressurize the cylinder to keep the valve up. You can also feed a rope in the cylinder if you don't have a good air compressor.
I've done tons of valve seals and springs with head on. The compressed air fitting screws into the spark plug hole. Needs a good supply of air like Dan said - like 90 psi. And watch out when you hook the air up as it will spin the engine as the piston is forced to BDC.
What heads do you have?? If we're talking something that uses the old umbrella type, unless they are missing or falling to pieces probably won't make much difference...
If you're already burning oil after only 3000 miles?.. I'd be more suspect that the rings didn't seat correctly before looking at valve-stem seals. Improper cross hatching patterns or even insufficient scratch depth can cause these issue too. Crosshatch pattern angle and depth is the lifeblood of a cylinder and needs to be right. And like Tom said above, if they didn't install positive style valve seals during the rebuild?.. then you will be fighting this issue forever and a day.
289, I just got done yanking an engine with 1,000 miles on it. It was burning a quart in a 100 miles. Turned out that the builder did not read the intake manifold instructions and forgot to install the baffle under the PCV. Had I ever imagined that scenario, I would have pulled the intake rather than the engine. Just throwing it out there as a possibility to save you some grief. Micah
