Removing head from seized engine
 

Have a 1967 250S with a 6cyl overhead cam engine. The engine is seized from sitting for 25 years . I've soaked the cylinders with kroil for 3 weeks and it wont budge. Crank damper nut wont move.

How do I safely remove the cylinder head to take a look and maybe tap the pistons. Cant turn the engine to get at TDC. Will I just have to cut the timing chain and then reset everything once I get the engine moving?

Thanks

It shouldn't be a huge deal to reset the timing on everything, assuming there are cam and crank marks for TDC. You can also use a paint marker to mark where it is now, and then return it all to this point on reassembly.

Don't think the chain would need to be cut...tie-wrap or wire the chain upward so it does not fall down into the front of the engine causing a jam. Unbolt the cam gear, move it forward off the camshaft and take the head off. Take pictures first!!!

Is the engine on a stand that can be rotated? If the oil pan can be removed it may be easier to determine what is stuck and to soak the bottom of the pistons and the wrist pins.

Good luck and keep us posted!!!

I agree that you don't have to cut the chain (although it might be time to replace it anyway).

If you can't find the order of cylinder head bolt removal for the M108 engine then I'd loosen them diametrically from the outside of each ends of the block inwards. (As generally tightening is made from the inner bolts outwards)

removing head
 

Thanks for the advice. I will take the cam sprocket off after I mark it.

Pack the cavity below the cam sprocket with rags before loosening the sprocket to prevent dropping anything inside the motor such as tools, a spacer or woodruff key.

Mark the front side of the sprocket to prevent putting it on backwards later.

Head removal
 

Thanks SB