engine trouble question

[mentalQtip]

Hi guys. '77 2 liter westy. I was messing with the exhaust working to quiet it a little. I was listening to it idle when I heard a sound of metal bouncing on metal and quickly shut it off. I stood and stared and thought about it and then started it again and no sound but now I had what my wife said looked like blue smoke coming out. Crap.
Not knowing what to do, I did what I could think of.

Pulled the valve covers and looked. The valve stems all appeared in line and all alike.
So I checked the compression. #1/140 #2/140 #3/125 #4/135

Still puts out the smoke and if I gas it there is a cloud of this smoke. Definitely not black.

I'm seeing that this will require pulling the engine and the heads. Any other steps first?

Thanks

Joseph

[Jadewombat]

That compression is good. You didn't hear this noise before the exhaust work? Did you drop a nut in the muffler, etc. and it could be bouncing around?

Rod knock would be pretty obvious.

[mentalQtip]

There was no sound after the very first time and I shut it off. Now it just smokes alot.

Looking at the plugs, they are all pretty black. The 3/4 plugs are oily in the threads and the #3 plug has what appears to be little bits of metal on the surface of the washer facing the piston. I've just been advised to drain the oil and check for metal also. Will do that.
I don't think that a nut went into the exhaust and with other clues(smoke/metal bits on #3) I suspect something else. A dropped valve guide? Very little idea what to even look for. I've pulled the valve covers twice and they just look all the same.

Thanks

Joseph

[Jadewombat]

Pull the valve covers again then and try rotating the engine 90 degrees then look at each valve. It will be very obvious if you dropped a valve seat.

[mentalQtip]

If a dropped valve seat is obvious then I don't have one. After rotating the engine every valve looks the same. Adjusted to .006".
The metal on the #3 plug and the smoke are all I have to go on. I didn't drain the oil yet. Should I? Should I just pull the engine and pull the heads? Somewhat clueless here.

Thanks

Joseph

[Piledriver]

Valve seats have been known to get so loose they can fall out, generate a bunch of noise from play in valvetrain, then end up back in the hole, "fixing" itself.

OTOH, if your valve adjustments are dead consistent, perhaps a squirrel threw something at you?

If you don't know how long the heads have been on there, or if the seats were replaced...
It's time.

You might be WAY better off finding some 1.7L heads from a 914 or 411/412.
You can sometimes get away with only changing the ex valves on those, and opening them up for 2L jugs.
(You also may gain a few HP as they flow better, even with the same size valves)

BTW, "NEW" AMC heads are little better than what you have.
They need to be built PROPERLY with ALL new valves/seats/guides/everything.

There are some vendors that do this. Make SURE they do this.
Some don't.
You tend to get what you pay for.

[Jadewombat]

You could also try a leakdown test before pulling the engine. It wouldn't hurt to change the oil either and take a look at any metal in there. If you don't see anything in the oil you take out of the engine, ONLY if you don't see anything obvious in the oil, I normally don't recommend this but you could pull the screen a have a look at it and any bits in the bottom of the case. Putting the screen back in not overtorquing is CRITICAL. I think it's 11ft./lb. to avoid damaging the camshaft. I try tightening the bolt slowly just until the screen stops leaking.

[wildthings]

the #3 plug has what appears to be little bits of metal on the surface of the washer facing the piston. I've just been advised to drain the oil and check for metal also. Will do that.

The washer isn't exposed to what goes on inside the combustion chamber. You could melt down a piston and nothing would get on the gasket. I think you are barking up the wrong tree here, especially with the consistent compression.

Did you have the intake apart at all while working on things? That would be the most likely source of foreign objects getting into a cylinder. Hard to imagine much of anything working backwards against both exhaust flow and gravity up through the exhaust ports.

Maybe a big hunk of carbon broke loose from the cylinder head and temporarily wedged between the piston and the head. It would beat like crazy for a few revolutions and then clear up. Not sure why it would cause the engine to blow blue smoke unless it broke a piston in the process, but then I would think the compression would be low on at least one cylinder.

[mentalQtip]

Well, maybe part of the question solved. A friend helped me to drop the engine and we started pulling stuff off the engine and this thing was just caked everywhere with old oil and dirt. I mean everywhere. (I thought it was running hot.) Anyway there were metal fragments(washer?) embedded in the #3 head chamber. I DID have the intake off before installing the engine. Also I believe the #3 oil ring is damaged. I can see the spring in one spot and not on the other oil rings.
I'm guessing the oil ring is the cause of the smoke and a washer was the cause of the sound. Could a washer get in the intake and somehow get to an oil ring and damage it? I don't really see how.
I'll be cleaning engine heads, cylinders, tin, and case for days. I wonder where that much filth could come from. I've had the bus and engine for a couple of years without driving or even examining the engine.

Thanks

Joseph