Crankshaft binds on 2.4L

[fackbell]

I’m in the process of replacing the cylinder head on my 2001 Olds 2.4L. When reassembling the timing chain, I found that I can no longer make a full rotation on the crankshaft. Something is stopping the crankshaft from completing the rotation a few degrees from TDC when I rotate the crankshaft in either direction. However, the crankshaft rotated without a problem before I pulled the head off. I have since removed the camshafts again so the valves are completely released. I’m trying to avoid removing the new head as it is a big hassle to disassemble the timing chain housing and I’d have to get a new head gasket, but I may have to for lack of any other ideas. It doesn’t seem like it is valve to piston interference though… Could it possibly be some binding with the balance shaft assembly? I'm at a loss here...

[Moppie]

Welcome to AF,


If you have taken the cam off, then all the valves should be sitting back in their seats.
It may pay to check they are, this will then rule out a timing issue etc.

How are the balance shafts driven?

[fackbell]

Yes, I'm thinking that my next move is to remove the head, something I've been avoiding as it is a lot of work and it doesn't seem to be the problem, but for lack on any other ideas I think I may need to do it.

The balance shafts are run off the crankshaft by a chain within in the oil pan area. From what I understand, the purpose of these shafts is to smooth out/change the engine’s resonant frequency as it was an issue in earlier versions of the engine. It looks as if the engine would have to be pulled to get the oil pan off to get at these shafts. If it comes to this I’ll probably junk the vehicle.

[Moppie]

Can you get easy access to the front of the motor, and check the full length of the chain?

It maybe something simple has become mis-aligned or slipped when you took the chain off to get to the cam.
Is it the same chain that drives the balance shafts?

[fackbell]

I actually found the problem. I pulled off the head again and found the broken head of a small screw embedded in the top of the cylinder head preventing the piston from completing its stroke. How it got in there I have no idea. Anyways, now back to getting it together again with hopefully no more issues!

[Moppie]

Originally Posted by fackbell

I actually found the problem. I pulled off the head again and found the broken head of a small screw embedded in the top of the cylinder head preventing the piston from completing its stroke. How it got in there I have no idea. Anyways, now back to getting it together again with hopefully no more issues!

Wow, that is an odd find.
Glad you fixed it though

Did you tape up the inlet and exhaust ports on the head after removing the manifolds?
It's amazing what can find its way into them.