what exactly are valve seals? Are these the little o-rings at the top of the valve stem?

What do they do, and what would happen to an engine's performance/oil usage if one was missing?

please help quick, I am trying to troubleshoot my engine...

 

Valve seals are "umbrella" shaped seals which fit around the valve and sit down on the valve-guide on the head - they keep oil from getting past the valve and entering the combustion chamber. If one or more go bad, you will burn oil.

 

car will smoke after start up..wont effect preformance at all.....mine got chewed up pretty bad after the cam isntall, and for a while i wasnt running any valve seals on 8 of em. I was quite suprised when i went to replace them

 

ah, interesting. other than burning oil, there's no other symptoms? Would the smoke from burnt oil come out into the valvetrain/topend or leave out the tailpipes?

And one other question.. what would happen if one was completely missing, and on top of that had an overtightened valve? Would the exhaust gasses escape into the topend?

I'm trying to figure out why my passenger side valvecover pressurizes (like blowby), but not on the driver's side valvecover...

 

My car started smoking a little after startup, so I diagnosed it with leaking valve seals, and slowly started purchasing the parts needed to fix it. Now 4 months later I just did an oil change, and burnt thru a quart of oil in 500 miles, Im hoping its just leaking seals gone worse and not the rings. Could the seals leak that much oil or am I going to get mad because its my rings.

 

Monk, if you lost a qt in 500 miles, I doubt that was just do to your valve seals. Worn valve seals may have contributed to the problem, but you need to look elsewhere as in rings.

I understand that forged piston engines have a tendency to burn a little more oil than engines with cast.

 

Valve seals stop oil from running down the valve stems. They don't control compression leakage. The valve seats would have to be leaking to get gases up through the valve guides. More often, blowby is caused by ring leakage.

 

Yeah thats what I was afraid of, I'm going to try and replace the seals by just taking the valve covers off. Thats going to be a project. Then I'll see how how long it takes me to burn another quart. I'm hoping that I just didnt put all 5 quarts in for the last oil change, it is possible since I use the 4 qt jugs of mobil1.

What valve seals should I get?

 

A set of viton seals from Combination Motorsports has worked well for me. $9 for the set.