Newbie here! Bought 2005 Aveo with 50,000 miles and two bent valves. Took head to shop put in two new valve guides all new valves. Installed. Started car up for a few seconds, motor racing about 4 grand shut it down. checked throttle cable, everything appeared correct. Started again same thing. Couldn't find anything. Tried the third time (third time is the charm) NOT! all the intake valves are bent. All my timing marks are still aligned. Haven't pulled head yet but exhaust valves appear ok. Intake buckets are not touching intake cam. Anyone have any thoughts on this? Could the motor racing cause the valves to bend? What could cause the engine to race like that.

 

You installed the head yourself ? After a machine shop repaired the head ?

Assuming you had the proper amount of oil in the engine and a good oil filter and oil was circulating proper , I doubt 4,000 RPM would damage the valves , although it is probably not good on the rest of the engine . For a cold engine .

Is this a 1.8l or a 1.4l engine . The 1.8l has a cam belt . The 1.4l has a chain , I think ?

You said you had the timing marks lined up . Are you aware the crank pulley / sprocket is 1/2 the diameter as the cam pulleys / sprockets ?

This means the crank pulley / sprocket makes 2 revolutions for every 1 revolution the cam pulleys / sprockets make . This means the timing marks can be perfect , and the cam pulleys / sprockets can be 180 degrees in error .

The timing marks should be lined up with # 1 cylinder at Top Dead Center on compression stroke . If the cams are 180 degrees in error , # 1 cylinder would be on exhaust stroke ( I think ? ) .

As to why the engine was racing , I would have to think about that .

Did you replace the belt , tensioner and idler pulley ( if it has a belt ) ?

God bless
Wyr