So here you will find a picture of the left-over bolt: http://www.pbase.com/macisaac/volvo&page=2

Also, there was a knocking sound when I took the car around the block, so I adjusted all the valve clearances to specs. Then there was no knocking sound for about 3 blocks, and then it started again, worse than before. It speeds up and slows down with the engine.

What started all this was the washer going into the 4th cylinder and welding itself to the piston head. There was some pretty hard banging when that happened. If my piston is damaged, would that be a knocking or tapping sound, or worse? Or is it possible I just didn't adjust the valves correctly?

Any ideas?

Greg

I suspect a bent wrist pin. That would sound like really bad piston slap as the binding of the pin would force the piston skirt against the cylinder wall pretty hard at both top and bottom.

The valve, even if bent a little (and your pictures don't indicate much damage to the valves) won't hit the piston crown. The amount of stress on the rod, piston, wrist pin and bearings when it attempts to compress the washer between the piston crown and head is immense.

Small bits of kaka shouldn't cause knocking and mis-adjusted valves souldn't either. A bent pushrod can certainly do it but none of the valves had a mark on the face indicative of having the washer forced against it. Pushrod check is pretty simple, remove them (one at a time) and roll across a flat surface like a piece of plate glass (although a typical formica counter is probably flat enough for a quick check).

I'm curious, did you remove the valves from the affected cylinder so inspect the seats? Were the nasty gouges smoothed out of the combustion chamber? Although they wouldn't cause a knock (unless you are describing a pre-ignition type "knock" which most certainly could result once things heated up in there).

Holed or cracked piston from after the reassembly (arising from stress to piston that wasn't immediately apparent) is a minor possibility. Check at PCV hose for lots of blow-by gasses.

Bent rod, bashed bearing are possibilities but less likely.

A very remote possibility is a fractured crankshaft. I've seen it but I still don't believe it.

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Mike!

You figure a little washer could bend a wrist pin? Ever see a wrist pin? Fracture the crankshaft - in a Volvo? You ever see a crankshaft?

We all know how sturdy a B30 engine is. We should all be trying to help on this site, not just be hypocritical to those that honestly try to supply a solution - right or wrong.
So, do you have an answer to the knocking sound? Could it be severe detonation? Remember, the noise went away after adjusting the timing. Perhaps the distributor was not tighten securely?

Klaus
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98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)

I did help. See my other post. The washer would have been pinched in the squish zone, and for sure could have cocked the piston to reduce the diameter at the skirt. That would make it sound like a hollow knock, that comes and goes. Retarding the timing would have also dropped the pressure enough to cause the knock to go. I just don't think scaring folks with the idea of broken crankshafts and bent piston pins, is a good idea. It didn't happen that way.

Could be that the skirt of the piston was collapsed by the bolt pinched in the squish area. If the noise changes with engine heat, that's what it will be.

Did you get rid of all the washer remnants in the cylinder? I had a screw go into my last engine, and just put a different engine in for the time being. Anywho, did you do your best to get rid of the parts that were sticking up in the piston? Get all the other junk out too if there was any? Could be a possibility.
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Kyle - '68 142? - Oregon Volvo Tuners?

Loose valves just make tappity tap noises. Not banging.
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I'm JohnMc, and I approved this message.

1st. Don't drive it.

Is that bolt the lower alternator pivot bolt?

It appears the washer got smashed up in the 'squish' area of the combustion chamber.

Did you have a valve job done? You might have bent a valve when the washer went in. Probably, in fact. It could be just enough to make the stem stick.

The bent valve could be sticking open in it's guide and hitting the piston.

How to check in place? I don't really have a good answer short of removing the valve spring and seeing if it sticks. You can drop the valve into the cylinder, so compress the cyclinder, or stick in a lenght of rope through the spark plug hole to prevent dropping the valve. If it sticks, the head has to come off anyhow.

Remove the head, save the gasket, have the valve guide and valve replaced. Replace the head.

If it's not a valve, it could be worse, below the piston crown somewhere.

Don't drive it.


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MPergiel, Elmhurst, IL '74 145e T-5 'Orange Alert'

I wonder how often stuff like this happens.

I just pulled a head, with a bent valve.

There were regular marks, like the sides of spark plug threads, I thought, on both the top of the piston and the inside of the head's combustion chanber.
The spark plugs were pretty well stuck to the head... never changed?
Could the lower portion of the plug separate, fall in...?

Unfortunately, by the time I got to it the 1 plug was missing, the one from the damaged cylinder.
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Gregg Shadduck, Mpls, MN -- 2x '87 745; '92 245; '67 Amazon