Loud metal clash while driving, no longer starts

[Chilezen]

Video of attempted start

Turns over, doesn't fire. There does seem to be a faint knocking sound on the bottom end.

I was driving normally, accelerating from a stop, and without warning I hear a loud metal-being-annihilated clash. It was similar in nature to grinding gears, but lower pitched. I coast to a stop and push it to a parking lot. Towed home.

There are no leaks, no fumes, no external damage within the engine bay.

Previously, for several months, this car would stall at idle and cut out during acceleration (but continue running). I don't drive it often for that reason. But otherwise it runs fine.

The timing belt is new and fine, it still rotates the cam. This leads me to believe the valves didn't hit.

I can't mentally piece together the loud sound with the car not starting, given that I hear no clashing sound during the attempt to start it. I don't understand why the engine still turns over if there *is* metal broken. And if there isn't metal broken, why won't it start?

[ahlem]

What do you see when you take off the valve cover? I'm guessing you broke your timing belt. You can pull the rubber cover off the front of the drivers side of the motor and look for rubber teeth.

[Chilezen]

The timing belt is new and fine, it still rotates the cam. This leads me to believe the valves didn't hit.

I haven't taken off the valve cover yet.

[15Michaeljoseph]

What do you see when you take off the valve cover? I'm guessing you broke your timing belt. You can pull the rubber cover off the front of the drivers side of the motor and look for rubber teeth.

+1 although when mine went it wasn't really metallic sounding, but you could hear the thwacks as the valves hit, really fast. that 'oh sheit' moment every e30 owner fears.


--Mike

[AndrewBird]

Pull the dip stick and see what the oil looks like and report back.

[vpilarrt]

Quote:
Originally Posted by Chilezen
The timing belt is new and fine, it still rotates the cam. This leads me to believe the valves didn't hit.

I haven't taken off the valve cover yet.

So how do you know that the cam still rotates?

[Chilezen]

So how do you know that the cam still rotates?

I have now pulled off the cover, the cam does indeed rotate:

http://youtu.be/WpchqsdaQHE

The oil on the stick looks clean, I changed it about a month ago.

A compression test is next.

[Chilezen]

Update:

[econti]

that's an issue

[AndrewBird]

You have at least one broken valve.

Ouch.

Pray it didn't take out a piston as well.

[Chilezen]

Cylinder 6 has no compression (I wonder why...). The rest are fine.

How can I check the valves? I can visibly see the rockers moving those valves.

--

Sooo, what do I do? I spent $2k on the rebuild only 1,000 miles ago.

[mr.vang]

Time for s52 swap

[Chilezen]

How can I check the valves?

The exhaust valve is still pressing against the rocker, even though the cam lobe is on the other side. It's as if the keepers aren't keeping it down.

I have no money for any swap or another rebuild. If the valve is the only problem, I may have enough $ (in time) to replace it, assuming the piston and cylinder wall is intact.

[smooth]

Sooo, what do I do? I spent $2k on the rebuild only 1,000 miles ago.

Call the person who did the rebuild.

[Chilezen]

Call the person who did the rebuild.

Thanks for the suggestion, but as you'll see in my sig, I did the rebuild.