Fuzi0n

My car puffs smoke the first 1-15 seconds when i start it and from all the reading i have done i believe its my valve stem seals.

Previously when i bought my car they told me it had a valve job done on it and the head got send to the machine shop. When they did the valve adjustment they didnt do it right and left one of the cyclinders open. So i was running on 3 cyls for awhile. I got the valve adjustment done and when that was finished we fired it up and it smoked for about 5-10 mins. Mechanic told me it was from all the build up in that cyclinder since it hadnt been fired in awhile.

Anyway so my question is how hard is it to change the valve stem seals? Anything i should watch out for or any specials tools I should aquire?

Thanks

- Fuzi0n