Unable to rotate engine by hand after valve seals replaced
#1
02-02-2018, 09:28 PM
Unable to rotate engine by hand after valve seals replaced
2002 V6 Manual
Not sure what went wrong but I was on my last cylinder of a valve seal replacement and tried to rotate engine by hand to get that last piston up top and it just would not budge past a certain point. In fact, it felt as though the crank bolt actually tightened slightly.
It's in neutral, all rockers, push rods and spark plugs are removed. There is 1 keeper unaccounted for but I'm having a hard time believing it could have fallen down and caused this.
Thanks!
Not sure what went wrong but I was on my last cylinder of a valve seal replacement and tried to rotate engine by hand to get that last piston up top and it just would not budge past a certain point. In fact, it felt as though the crank bolt actually tightened slightly.
It's in neutral, all rockers, push rods and spark plugs are removed. There is 1 keeper unaccounted for but I'm having a hard time believing it could have fallen down and caused this.
Thanks!
#3
02-03-2018, 12:44 PM
#4
02-03-2018, 05:28 PM
I went fishing in the cylinders with a magnet at pistons in the up position and came up empty. I even gave each a shot of compressed air while the magnet was in there.
I did however rotate the engine counterclockwise and the same hard stop occurs almost 360 degrees the other way, maybe 20 degrees short of it.
I did however rotate the engine counterclockwise and the same hard stop occurs almost 360 degrees the other way, maybe 20 degrees short of it.
#6
02-03-2018, 06:49 PM
Thanks!
#7
02-04-2018, 03:07 AM
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#8
02-06-2018, 03:04 PM
#9
02-06-2018, 04:13 PM
I went fishing in the cylinders with a magnet at pistons in the up position and came up empty. I even gave each a shot of compressed air while the magnet was in there.
I did however rotate the engine counterclockwise and the same hard stop occurs almost 360 degrees the other way, maybe 20 degrees short of it.
I did however rotate the engine counterclockwise and the same hard stop occurs almost 360 degrees the other way, maybe 20 degrees short of it.
You moved the pistons to the bottom each time you went fishing for lost parts, right?
You need the piston at the bottom so you can get all of the way around the cylinder wall. You won't get to the corner of the piston top and the cylinder wall if the piston is raised. The pistons that are at the top of the stroke right now are the ones you want to move to the bottom so you can go fishing with your magnet.
Last edited by JDStrickland; 02-06-2018 at 04:17 PM.
#10
02-06-2018, 06:27 PM
You moved the pistons to the bottom each time you went fishing for lost parts, right?
You need the piston at the bottom so you can get all of the way around the cylinder wall. You won't get to the corner of the piston top and the cylinder wall if the piston is raised. The pistons that are at the top of the stroke right now are the ones you want to move to the bottom so you can go fishing with your magnet.
You need the piston at the bottom so you can get all of the way around the cylinder wall. You won't get to the corner of the piston top and the cylinder wall if the piston is raised. The pistons that are at the top of the stroke right now are the ones you want to move to the bottom so you can go fishing with your magnet.
Thanks!
#11
02-07-2018, 03:59 AM
I thought of something else. In tapping on the tops of the valve spring retainers to loosen the keepers before compressing the spring, would it be possible to break off a piece of the valve head? I guess I could introduce compressed air again into the last cylinders I worked on and see if much air escapes. It shouldn't since all the valves should be closed now.
Thanks!
Thanks!
#13
02-07-2018, 07:42 PM
#14
02-08-2018, 01:15 PM
Turn the engine one way and mark where it stops, then turn it the other way and see if it stops in the same place. Also, observe the valves and see if they are closing fully, this could be a problem where the piston is hitting a valve. If the engine can go all of the way around when going backwards, then try going forward again.
Cut some sticks (dowel pin material) that are longer than the piston stroke -- if the stroke is 6 inches, cut your sticks to 10, whatever -- so they do not fall inside of the engine. Then as you turn the engine by hand, you will see which pistons are up when the crank stops turning. this will narrow your search to not more than 2 cylinders -- one is at the top of the exhaust stroke, the other is at the top of the compression stroke. You expect a valve to be open at the top of the exhaust stroke, this valve will be making the transition from open to closed, and the associated intake valve will be changing from closed to open. The piston at the top of the compression stroke should have both valves closed.
Cut some sticks (dowel pin material) that are longer than the piston stroke -- if the stroke is 6 inches, cut your sticks to 10, whatever -- so they do not fall inside of the engine. Then as you turn the engine by hand, you will see which pistons are up when the crank stops turning. this will narrow your search to not more than 2 cylinders -- one is at the top of the exhaust stroke, the other is at the top of the compression stroke. You expect a valve to be open at the top of the exhaust stroke, this valve will be making the transition from open to closed, and the associated intake valve will be changing from closed to open. The piston at the top of the compression stroke should have both valves closed.
#15
02-08-2018, 10:17 PM
Turn the engine one way and mark where it stops, then turn it the other way and see if it stops in the same place. Also, observe the valves and see if they are closing fully, this could be a problem where the piston is hitting a valve. If the engine can go all of the way around when going backwards, then try going forward again.
I have done that and it will turn almost a full 360...I'm guessing about 20 degrees short of that.
Cut some sticks (dowel pin material) that are longer than the piston stroke -- if the stroke is 6 inches, cut your sticks to 10, whatever -- so they do not fall inside of the engine. Then as you turn the engine by hand, you will see which pistons are up when the crank stops turning. this will narrow your search to not more than 2 cylinders -- one is at the top of the exhaust stroke, the other is at the top of the compression stroke. You expect a valve to be open at the top of the exhaust stroke, this valve will be making the transition from open to closed, and the associated intake valve will be changing from closed to open. The piston at the top of the compression stroke should have both valves closed.
I have done that and it will turn almost a full 360...I'm guessing about 20 degrees short of that.
Cut some sticks (dowel pin material) that are longer than the piston stroke -- if the stroke is 6 inches, cut your sticks to 10, whatever -- so they do not fall inside of the engine. Then as you turn the engine by hand, you will see which pistons are up when the crank stops turning. this will narrow your search to not more than 2 cylinders -- one is at the top of the exhaust stroke, the other is at the top of the compression stroke. You expect a valve to be open at the top of the exhaust stroke, this valve will be making the transition from open to closed, and the associated intake valve will be changing from closed to open. The piston at the top of the compression stroke should have both valves closed.
Thanks!