Back and fourth play in crankshaft 2006 trailblazer 4.2

[CASHKJ]

Hi,
Still working on 2006 trailblazer trying to find tapping noise.I noticed that when I turn the engine by hand that there is what feels like back and fourth play in the crank is that normal?I have the valve cover off and if I stick a screw driver in the spark plug holes to watch piston come up it does look like it affects the pistons movement.

Thanks!

 

[CaptainXL]

Hi,
Still working on 2006 trailblazer trying to find tapping noise.I noticed that when I turn the engine by hand that there is what feels like back and fourth play in the crank is that normal?.
Thanks!

Sure it's normal but you cant just go by feel. You need a dial indicator to check thrust bearing clearances. Even then it should only be a very small amount of movement. Clearances are in the Haynes manual under the engine rebuild section.

 

[ByCo]

My first thought when I listened to the video in your other thread was that the thust bearing was bad but I dismissed the thought because it's fairly rare. The only time I've seen it happen was after a transmission was replaced and the shop that did the work didn't get the TC fully seated on the input shaft, we went through two engines before we figured it out.

 

[CASHKJ]

The play that I am talking about is when I rotate crankshaft clockwise or counter-clockwise not pulling or pushing crank.It seems there is a little play when rotating crank not pulling or pushing crank.I may not be explaining it properly.

 

[CaptainXL]

The play that I am talking about is when I rotate crankshaft clockwise or counter-clockwise not pulling or pushing crank.It seems there is a little play when rotating crank not pulling or pushing crank.I may not be explaining it properly.

Your feeling timing chain slack more than likely. Its not a problem cause when the engine is not running there is no oil pressure tightening it up. If your cam to crank correlation was off you would get a CEL.