Crank shaft lock?

[Preacherman]

07 mkz 3.5lt engine.
I'm trying to line up tdc and the crank shaft locks up just a touch before the cam shaft lines up. I can then turn the it back counter clockwise one cam shaft revolution and then it locks up again. Anyone know what is up with that?

 

[p238shooter]

I am sure others here will chime in who know about this particular motor, but if this is a motor your are building, sounds like you might have a valve contacting a piston top. I would back track from that point of view to take a look at things. Are you sure the markers you are using are the correct ones?

 

[Preacherman]

Yes, they are the correct markers. The engine is still in the car but the motor mounts are disconnected. The dumb thing has an internal water pump that I'm trying to get out

 

[swampratt]

I also feel a piston is contacting a valve.

That tool may help.

 

[Preacherman]

I also feel a piston is contacting a valve.

That tool may help.

Thank you. I have this tool but the crank is not rotating to the place it needs to be to use it. I don't doubt you guys I just don't how a valve is now getting in the way. The heads have not been removed or anything touched under the valve covers such as cams etc.

 

[swampratt]

did you remove the timing chain or loosen it.??
It takes very little slack to get the valve to hit a piston in some vehicles.
Normally you would have a minimum of .120" clearance for piston to valve contact.

Note that the piston is NOT all the way up the bore during this time when the valve is fully open.
You change where the crank and cam clocking is at and you will change piston to valve clearance.
1 tooth off it may hit.. or 1 tooth off the other direction and you could double the piston to valve clearance.

 

[Preacherman]

did you remove the timing chain or loosen it.??
It takes very little slack to get the valve to hit a piston in some vehicles.
Normally you would have a minimum of .120" clearance for piston to valve contact.

Note that the piston is NOT all the way up the bore during this time when the valve is fully open.
You change where the crank and cam clocking is at and you will change piston to valve clearance.
1 tooth off it may hit.. or 1 tooth off the other direction and you could double the piston to valve clearance.

No, I have not removed the timing chain yet. I'm trying to get tdc lined up so that I can place the cam tools.

 

[swampratt]

If you have not removed anything and not disrupted where the timing chain is at then I have no idea why it is not rotating all the way around.
Spark plugs are out I assume and nothing fell down the spark plug holes.
Tensioner is not binding up for some odd reason.
HHHMMM???

 

[Cowcatcher]

If you have not removed anything and not disrupted where the timing chain is at then I have no idea why it is not rotating all the way around.
Spark plugs are out I assume and nothing fell down the spark plug holes.
Tensioner is not binding up for some odd reason.
HHHMMM???

I was wondering if the plugs were out.

 

[swampratt]

With Preacherman jumping into a task like this i would "assume" it is not his first rodeo and the plugs are out and he would know what it feels like to turn a crank against compression..and turning in reverse i would think there was not any compression.

I could be all wrong though and I think this has some VVT also and that throws another monkey wrench in the mix.

I sure like my old cars

It's a mystery.