Camshaft gear pin sheared off 2000 Corrola, other problem.

[mikmic2]

So my mother is driving her 2000 Prism, (same thing as a Toyota Corolla) with a 1.8 DOHC at about 65 mph. All of a sudden she said it felt like somebody slammed the brakes on for a second. She has an automatic transmission. She said that it then let loose and she coasted over to the side of the road, and it barely turned over. After waiting a while it turned over a little better she said, but still wouldn't start. She is 100 miles away, so I load up the tools and get down there about 6 pm. I noticed it was backfiring through the intake. So I take the valve cover off, and notice the intake camshaft isn't spinning.

It sheared the pin on the intake camshaft sprocket so the intake camshaft didn't spin anymore. So after an hour or so, I get the half of the pin out of the camshaft. Then I'm thinking to myself, I sure hope this isn't a zero clearance engine. Naturally I forgot my compression tester, so I do with what I have. On each cylinder I turn the camshafts so all four valves are closed and blow into the spark plug. Every cylinder seems to be not leaking any air, except cylinder 3. I then noticed that even with both lobes not touching the lifters, that both intake lifters on cylinder 3 are about 3/16 of an inch farther down then the rest of the cylinders are during the compression stroke. So I'm wondering if the valves got bent, or something got lodged between both valves in the head, that are stopping them from returning to there up position.

I don't know if the pin busting on the intake camshaft sprocket caused the problem. Or some other problem caused the pin to bust. Either way it looks like I have to take the head off to see what the problem is.

I was just wondering if anybody had any ideas as to what the problem might be, and what caused it?