Can I fix steam radiator shut off valves or do I have to replace

Hello,
I have steam heat in my condo and sometimes it gets too hot and I would like to be able to turn off the steam supply to some of the radiators.

The problem is that even when I crank down on the valves steam still goes into the radiator. It is a very old building and I wouldn't be surprised if the radiator valves are original and the gaskets/discs in the valve are worn.

So my question is do I have to replace the valves or is there any way to take out the stem part and replace just that. Any other suggestions?

Thanks

Thanks for the response but all the air vents are working OK and can regulate the heat a little bit ...as much as you can regulate steam heat.
The steam is a single supply (4 floor condo building) - only one pipe in to each radiator and no return so if I shut it off wouldn't have any impact on the other radiators.

Any way to fix the valves so that when I turn the handle it really staops the steam entering the radiator?

different seals

There is a difference between seal replacements for valves. They make special seals for hot steam applications but not every plumbing place handles them. I am fortunate enough to have a plumbing supply place in my area that handles them and this time of the year I always make sure I carry them.
Check with your local plumbing supply. When you remove the stem from the valve make darn sure you have the supply to the radiator OFF so you dont get burned. I also make sure that I have an assortment of new screws that hold the new washer in place because the old screw is so rusted or corroded from time that I have to use a needle nose vise grip to get the old one off. In one large apartment complex I work on in Milwaukee there is no way to shut off the heat to an individual apartment without shutting the entrie buildings heat down. So in that case I have replacement stems ready ahead of time and when the heat cycles off in a steam system I pull the old and put in the replacement before it cycles back on. I dont recommend this technique to anyone other than experienced people. Also in some cases I will remove the old valve entirely and replace it with a thermostatically controlled valve with a one 0 to 9 setting on the face dial so each radiator can be controlled independently in each room.

tonysprofessionalremodeling.com

washers

Steam valves use a hard washer, often held on by a nut and metal washer, which may not be available in all locations. You may also have a difficult time disassembling the valves to install the washers.

You might also just replace the air vent with a plug, if an existing air vent can't be throttled down enough.