Elite Engine Problem

[Tanz]

A friend of mine is having a problem with the engine in his Elite.
The car was on the drive with the engine ticking over when there was suddenly 'a loud tinkering noise' so he quickly turned the engine off and pushed the car back into the garage. Then he removed the plugs and tried to turn the engine by hand. It would turn so far then lock solid. If he turned it backwards the same thing happened. Looking down the plug holes it locks when cylinders 2 & 3 are at the top. The car didn't back fire when it was running on the drive.
Any thoughts welcome

[JB455]

I know this should be obvious, but worth asking- is the cam belt intact?
If he has a borescope I'd take a peek through the plug holes to see what is making contact. If not, and the belt is intact, I'd pull the cam covers off to see if any of the valves are sticking.

[MetBlue]

Maybe the timing belt has jumped a tooth on the crank.
Check the timing mark alignments.
Tony

[Tanz]

I know this should be obvious, but worth asking- is the cam belt intact?
If he has a borescope I'd take a peek through the plug holes to see what is making contact. If not, and the belt is intact, I'd pull the cam covers off to see if any of the valves are sticking.

Thanks for the reply: The cam belt is intact but very old and overdue to be changed. We removed the inlet manifold and inlet cam cover. All the valves appear to be moving on the inlet side but No 2 cylinder cannot be checked as when turning the engine over by hand, the engine locks up before the high part of the cam can act on the bucket. I took my borescope and had a look down the plug holes but couldn't see anything wrong. The only clue was the top of piston no 2 looked slightly shiny as if something had made contact with it. I think we are going to have to pull the head off was praying for an easy fix.

[Tanz]

Maybe the timing belt has jumped a tooth on the crank.
Check the timing mark alignments.
Tony

Thanks for the reply Tony.
The timing marks all line up - Crank at TDC and the marks on the pulleys. I guess if it had jumped a tooth or 2 and made contact with a valve no matter how slight, we would still have to pull the head to check for damage.

[Marten]

I know this should be obvious, but worth asking- is the cam belt intact?
If he has a borescope I'd take a peek through the plug holes to see what is making contact. If not, and the belt is intact, I'd pull the cam covers off to see if any of the valves are sticking.

Thanks for the reply: The cam belt is intact but very old and overdue to be changed. We removed the inlet manifold and inlet cam cover. All the valves appear to be moving on the inlet side but No 2 cylinder cannot be checked as when turning the engine over by hand, the engine locks up before the high part of the cam can act on the bucket. I took my borescope and had a look down the plug holes but couldn't see anything wrong. The only clue was the top of piston no 2 looked slightly shiny as if something had made contact with it. I think we are going to have to pull the head off was praying for an easy fix.

First check for a bent valve is by measuring the valve clearances.

If you presurize the cilinder with the valves closed and the piston at tdc (put the transmission in gear to lock the engine) it should become pretty clear To pressurise make (or buy) something like sparkplug with the guts knocked out and a tyre valve brazed on top.

The spring loaded cam tensioner is a failed design imho