I've got a real mystery here with my timing belt. I had just replaced my (TAC) throttle actuator control and PCM and the car was running fine. No codes, smooth idle, and good power. I pulled it into the shop to replace the timing belt (68K).
As I was turning over the engine with a wrench on the crankshaft to line up the marks, I got resistance about half a revolution through and the engine wouldn't continue to turn over by just using the wrench.
The marks weren't close to being lined up yet, so I made the fatal mistake of using the starter to roll over the engine to get the marks close. Well, I probably bent the valves in the process and it was a stupid mistake, but at the time it didn't even cross my mind that the marks wouldn't line up. I mean I had just driven the car.
Anyways, as I line up the camshaft marks with each other, the crankshaft is about 5 teeth off, roughly 90 degrees. I mean it's not even close.
And yes, I know the crank revolves twice for every time the cams rotate once.
Well, I've never had this happen before. How the heck did the car run? The original belt I'm taking off isn't broken nor missing teeth nor does it have any oil on it. It looks really good.
I'm the original owner of the car and have never had any trouble with the timing belt and this is its first replacement.
After I realized my probable mistake, I put on the new timing belt anyways. I lined up the timing marks properly after taking off the old belt. Once lined up and with the new belt on, the engine rotated freely all the way around with a wrench as it should.
I hoped I might have gotten lucky and tried starting it, but no, the car wouldn't start. It just turns over. I have spark and fuel pressure.
So my next step is going to be a compression test. Assuming my compression is next to nothing in one or more cylinders because of bent valves, I'll remove the head and examine the valves.
But how in the world was the timing of the original belt off in the first place when the car was driving fine. The only possible explanation I've heard so far, is that the crank bolt and the serpentine belt pulley held tension on the crankshaft timing belt pulley, and that when I loosened the crank bolt to remove the serpentine belt pulley, that tension was released from the crankshaft timing belt pulley and allowed it to move.
Any ideas. I'm at a loss.