possible sticking/bent valve...help!!

[garntea]

Hello to all...im new here so thanks for the forum....I have a 05 Rio bought at auction...The car runs ok...not great, if your going flat but when you hit a hill you can tell something not exactly right...there is a miss or skip, which i could deal with if thats all was wrong....real problem is sometimes as your taking off from a stop gaining speed, particularly if there is a little incline, a clacking or knocking sound can be heard from engine and smoke will pour out of the exhaust, white with a little blue tint maybe..no smoke at all unless this sound is heard....starts up perfect every time....i am aware of this being interference engine type...timing belt looks good but have no idea when it was changed.....does this sound like a bent or sticking valve?....maybe someone didnt change the belt soon enough in the past?...car sometimes will go 3 or 4 days with no problems then it will do it 3 or 4 times in one 25 mile trip to town and back....doesnt use any oil unless the smoking thing occurs then i have to add....120k mileson car......any help will be appreciated, thanks!!!!

[Mkast]

Preform a cylinder leak down check.

[Wry 'Cuda]

If the belt had been a problem in the past causing bent valves, you wouldn't have an intermittant problem; -the engine wouldn't go at all. As you say, it could be a sticky valve and/or bad oil seal on the valve.