yuel

i just took the heads off my car because i was told it had burnt valves, the car would not idle correctly, runs great when moving, checked everything and so did the dealership, the head is now removed, how can i tell if the valves where burnt? some valves are black, some are white and some are inbetween colors. looks like the intake valves are all black and most of the exhaust valveses are white or whitish

R1UK

When you talk about burnt valves, its not really the colour thats the problem, tho that can give an indication of weak or rich running etc.
It refers often to that little lip around the valve known as the valve seat. Its where its supposed to form a gastight seal for combustion when in the closed position.
Sometimes valves can burn out, and you see bits of the valve actually "missing" or burnt away.
This is most often caused by too much heat, ie: wrong valve clearances, wrong ignition timing etc etc, theres quite a few reasons.
So really check the "edge" of the valve not the face.
And also that part of the head where the valve seat and the valve meet.

yuel

well one more question, all the valves edges looks good, no chips or anything, but the cyclinder is different from all others in color, the exhaust valves are white and intake are black, but both intake and exhuast valves is white, could that be a sign of the stuck valves or something? thanks

ede

burnt valves will have part of the valve head missing from being ate away from exhaust gas

R1UK

Sticking valves can cause misfires amongst other things, now if you have 3 sets of valves [say you have a four cylinder car] and the exhausts and inlets have matching colours, but say one cylinder has valves of a different colour, then there may be a problem.
If they are both white as yours is, its maybe running weak, so it could be an air leak, or a head gasket leak, theres quite a few options.

ede

little late now but a smart first move would of been to run a compression check or leak down test, that would of told you a lot without removing the first bolt

R1UK

Now that would have been a better idea.

yuel

your right, i should have done a compression check but i thought about that after tearing into the engine. i do my best thinking after the fact and its to late. but yeah one set of valves is different from the others, both valves are whitish while the other 3 sets are white and black. thanks for your guys input

Lo-tec

I would take them to a machine shop, and have someone there take a look at it. Is the piston in the cylinder in question really clean? Possible blown head gasket?