2002 Blazer. I was driving and the truck just shut off. Me and a buddy agreed the timing chain jumped. So I changed the gears and chain. The chain seems slightly loose, but it only deflects about a 1/4". There was no tensioner on the chain. Truck turns over and acts like it wants to start, but not quite. I took the dizzy cap off to look at the contacts and clean them. When I grabbed the rotor, I noticed if I lift up the rotor slightly and turn it, I can turn it 90 degrees. If I don't lift it, I can still turn it 45 degrees. The screws are tight. It's the rotor shaft that is turning. Maybe the pin that holds the gear on the rotor shaft is sheared? Or teeth are broken off the cam or rotor shaft gear? Or is the rotor supposed to turn like that?

 

Personal experience - our dist. shaft bearings wear out.
1/4" play/push in a timing gear chain is normal. I can't see a timing chain or distributor mucking up all of a sudden & shutting the engine off.
I had a fuse under the hood that would pop (can't remember which one right now) from a wire making inconsistent connections.
Look for popped fuses... but again that's my experience.

 

Checked all fuses underhood and in dash. All good. Just wanted to know if the play in the distributor is normal. I don't think you should be able to twist it that much.

 

Figured it out! The teeth on the bottom of the dizzy were worn off on one side. I took the cap off and had my kid turn over the engine. The rotor wasn't turning, so i pulled the dizzy. The teeth weren't broke or chewed, just worn. YAY! Now i just have to replace it, should run.

 

Pay close attantion to the position of the distributor when you remove it. The new one HAS to go back in the exact same rotation position.

 

Worn distributor gear is a symptom, the cause is worn distributor shaft bushings, very common on this engine. Time for a new distributor, if you replace just the gear, it will wear out just like this one did.

Now that you've got the timing cover off, it must be replaced, don't reuse it. After it's all back together, the crankshaft position sensor relearn must be performed with a capable scan tool. If not, the PCM will use old data which is now incorrect.