dapalong

Had a really bad day Saturday. My 03 Z06 was on fumes, so I pulled in a Shell station and put in 10 gallons of 93 octane...the same stuff I've been running in it. I leave the gas station, and a few blocks down the road, the engine starts making a nasty sound. I've never blown up an engine before, so I don't know how to describe the sound, other than to say it was still running, but very noticeable. I coasted for another two blocks, pulled it off the road, and shut it off. Made sure there weren't any fluids coming out of it. Hopped back in a few minutes later, and it won't turn over. I'm fairly sure the engine is seized up. From the time I left the gas station, it was never over 3,000 rpm, and was running for maybe 90 seconds when this happened.

Any thoughts? Could bad gas somehow cause this? Have not yet torn anything apart.

Thanks,
Mike

RPM WS6

iTrader: (3)

I have a couple of questions:

1) If you were "on fumes", why did it only take 10 gallons? I don't recall the Z06s having a smaller gas tank than a regular C5 (unless they do, I could be wrong). I'm just wondering why you weren't able to get more gas in the tank (and/or maybe the tank wasn't as low as you think it was), unless maybe you purposely bought only 10 gallons. This might not matter, but I just want to understand this part of the situation.

2) So if it really was down to just fumes, I wonder if the fuel pump is now damaged from overheating or perhaps the filter has become clogged? When you try to start the engine does it crank at all? Click? Absolutely nothing? Have you tried to manually turn the crank to see if it's actually seized?

dapalong

It it was on fumes but I didn't fill it up. I don't drive the car a ton so I usually don't put a full tank in it, not wanting to leave the fuel in there too long.

It doesn't crank at all. It clicks but does not turn over. To see if the crank would turn, I put it in 6th gear and rocked it back and forth while watching the crank pulley. It did not move at all.

dapalong

Found the issue. #4 cylinder, broken valve spring. No idea why it happened.

Chpbstrd

Damn. How did you decide to look at the head first? Did a compression/leak down lead you there?

dapalong

By accident. Since the engine wouldn't turn over, we were in the process of removing the spark plugs, and were going to put a socket on the crankshaft bolt to see if it would turn over. Pulled the #4 spark plug and saw it was destroyed.

Biebs

Not bad gas just bad luck. Looks like a top end rebuild minimum - depends on damage to cylinder wall or bent rod.

How many miles on this engine and did it have modification to the top end??

dapalong

Yep, very bad luck. We'll stick a scope in there to try and gauge the extent of the damage before pulling it apart. If it looks catastrophic, I'll probably just park it for a while and focus on the Javelin.

38,xxx miles on it. So the original owner (2 owners before me) had some work done to it. From the outside, I can see that it's got an aluminum intake and headers. There is no paperwork on the internals, but I'm sure it has a camshaft, and was told it had work done to the heads. There is a dyno sheet from about 8 years ago, showing it made about 420 WHP. My buddy is guessing that they put in a bigger camshaft, but the springs look stock...and one of them eventually gave way.