Oh Crap! I think I just killed it.

[Sluggo]

Starting the Bus up to take my son to his doctor appointment. Heard a sound like someone breaking metal with a giant hammer and then Ka-Chink.....Ka-Chink.....Ka-Chink..... in time with the engine rotation. Immediately shut off the engine and used the Toyota. When I got back I pulled my little Fuel Pump Pushrod fix and that was fine. It sounds like a piston broke and is just banging around. I'll be dropping it this weekend. We reused the pistons & cylinders. Maybe that was a mistake. They checked out when we inspected them!

[chitwnvw]

Dang, Sluggo. I don't think I could have even posted that message, I'd have come home from the doctor and handed the baby to the wife and crawled under the covers. Probably would have cried myself to sleep. No shame in that. I know it's all in learning about your bus, but it's nice to get to drive it a couple of thousand miles ‘tween major disasters now and again.

Well I hope it’s not a thrown rod or the like. Good luck.

[Amskeptic]

Starting the Bus up to take my son to his doctor appointment. Heard a sound like someone breaking metal with a giant hammer and then Ka-Chink.....Ka-Chink.....Ka-Chink..... in time with the engine rotation. Immediately shut off the engine and used the Toyota. When I got back I pulled my little Fuel Pump Pushrod fix and that was fine. It sounds like a piston broke and is just banging around. I'll be dropping it this weekend. We reused the pistons & cylinders. Maybe that was a mistake. They checked out when we inspected them!

This is so damn painful I am almost in tears. That was a beautifully smooth engine that you and Bottomend put together. Be a forensic pathologist, inspect carefully as you disassemble. Please let us know what you find. Used pistons and cylinders are not in themselves a mistake. If they measure out, they measure out. Please remember, if an engine makes it past the first 20 minutes of break-in with no funny noises etc, you have established that you put it together with suitable clearances. A massive failure 1,000 miles into it suggests metallurgical failure. Start with an inspection of all valve spring heights. If one retainer is wedged against the rocker arm, it was a valve drop. Bad keepers? AMC heads, like Jake Raby said, have trashy valve components.
If heads are OK, battered valves and heads but not dropped, but you have a connecting rod all over the place, did you have a connecting rod nut loosen? God I hate this, Sluggo, I hate seeing hard work get blown up.
Colin

[satchmo]

"I feel your pain, again." (said with Bill Clinton accent).

Let us know what you find.

Good Luck, Tim

[Sluggo]

Checked the valves. Nothing too tight or loose. Can only crank the engine by hand about half way before it locks up. Something in the block is broken or came loose and is keeping it from turning. Have it ready to drop. I'll be doing that tomorrow.

[Sluggo]

Dang, Sluggo. I don't think I could have even posted that message, I'd have come home from the doctor and handed the baby to the wife and crawled under the covers. Probably would have cried myself to sleep. No shame in that. I know it's all in learning about your bus, but it's nice to get to drive it a couple of thousand miles ‘tween major disasters now and again.

Well I hope it’s not a thrown rod or the like. Good luck.

I really doubt it's a rod. They were in excellent shape and we did a good job on those nuts. Used Loc-tite too. Impossible to tell before I drop it and split it but I just have a gut feeling it's a piston. #3 to be exact. It had bad compression, there was oil coming out from between the #3 cylinder & head and Colin said he thought he might have heard a slight piston slap when he was here. Plus it sounded like something broke and then made a hard sliding sound (like dump truck brakes) and chink repeated in time with the engine rotation.

[joe_westy]

Are you sure the valves are OK?

Try having someone turn the engine as you observe the valve move. It sounds like a valve hung up and the sould you hear is the valve hitting the top of the piston.

If you're lucky you might be able to replace the valve guide, valve and maybe the one piston.

[Amskeptic]

Are you sure the valves are OK?
Try having someone turn the engine as you observe the valve move.

Any valve-to-rocker clearance means that the keepers are good, and the valve is likely intact. If you find a valve with no clearance at that cylinder's TDC firing position, it is a suspect.

I am going to cross my fingers and hope it is a simple enough piston.
You know. . . . . . skirts can crack if you rotate an engine with pistons installed but no cylinders yet. Can look like a minor moment

Awaiting your discoveries,
Colin

[Sluggo]

Pulled it apart today. Started on the 3/4 head because of my hunch. Didn't take long to find the problem.

Diagnosis:

Dropped #4 Intake Valve Seat.

[albumimg]319[/albumimg]

Also confirmed the #3 oil leak.

This is the damage to the #4 Piston.

[albumimg]320[/albumimg]

I'll be bringing the head to my machinist on Monday.

I checked the lifters & cam lobes. They look perfect. No pits or dings. Rockers are fine. I'll check the pushrods tomorrow.


Questions:

1. Is that a lot of carbon for 800 miles?
2. Should there be oil in there?
3. Is that piston shot? The dent is about 1/8".
4. Can I seal the head to the piston with Permatex to stop the leak?
5. Anything else I should check for?

[Sluggo]

Are you sure the valves are OK?

Try having someone turn the engine as you observe the valve move. It sounds like a valve hung up and the sould you hear is the valve hitting the top of the piston.

If you're lucky you might be able to replace the valve guide, valve and maybe the one piston.

You were damn close!

[Westy78]

That really sucks but it could have been much worse if that valve head had popped off and put a hole through the piston. Where these AVP heads or rebuilds from somewhere else? That piston doesn't look to horrible. You might be OK with filing any high spots to avoid pre-detonation and reuse it.

[Amskeptic]

1. Is that a lot of carbon for 800 miles?
2. Should there be oil in there?
3. Is that piston shot? The dent is about 1/8".
4. Can I seal the head to the piston with Permatex to stop the leak?
5. Anything else I should check for?

1) Not necessarily for an engine that has mostly puttered around on surface streets. Some is caused by oil coming up past the rings.
2) Not to that degree. How were the cylinders honed and what kind of rings?
3) No, it can be smoothed out. Check the ring lands very carefully if you pull the cylinder. You want absolutely consistent gap across the land and the top of the ring. If it gets tight at the scene of the damage, then the piston has collapsed a land, replacement is then called for.
4. No. The leak is a symptom. Sealing would be a mask. Sealing is also not allowed. You may lap the cylinder barrel to the head. Does the fin boss hit the head before the very top of the cylinder contacts the head sealing surface? I had a head flycut too deep and the cylinder fin area was contacting the outside of the head. I got 100,000 miles out of it, but the heat was always stinky due to leaking when the engine was cold.

[Sluggo]

That really sucks but it could have been much worse if that valve head had popped off and put a hole through the piston.

That's exactly what heppend with my Jetta when the timing belt broke. Two valves were completely embedded in the piston. I pulled one of the valves out of the piston and it hangs from my rearview mirror.

Where these AVP heads or rebuilds from somewhere else? That piston doesn't look to horrible.

Those are slightly used and reconditioned original VW 1.8 liter "big valve" heads.

You might be OK with filing any high spots to avoid pre-detonation and reuse it.

That's what I was hoping. I plan on getting some new poistons & cylinders anyway. If I could make these last 5,000 miles I'd be good.

What about my other questions?

[Westy78]

What about my other questions?

See above.

[Amskeptic]

What about my other questions?

WHADDABOUT 'EM? HEH? My answers not GOOD ENOUGH FOR YA? HAH?
Colin :blackknight: