Dropped Washer in #1 Cylinder. Opinions??

drola · 12-01-2016, 06:33 PM

as careful as i thought i was being and as much as i made sure nothing fell when i took off the intake on this 2.7, a pesky washer fell in to the number 1 cylinder. i know something was up because the engine would not spin the full 360 degrees but for the life of me could not determine the cause. i was already mentally prepared to split the case to see what was up when i took one more look and behold i noticed the bottom of the piston had some odd looking marks. so i turned the crank until the cam was opening the intake valve, turned the adjustment screw all the way in, and i saw something odd. stuck my thin magnet and viola. damn washer. it was crushed by the piston. from what i could see, there is no damage to the exhaust valve.
take a look at the pic. do you guys think i will have a problem? it is not gouging the cylinder walls but it is close. i'm afraid with the heat it may expand and do some damage. as of right now the walls look perfectly good. the pic looks like there is damage but that is just the reflection

drola · 12-01-2016, 06:41 PM

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drola · 12-01-2016, 06:56 PM

drola · 12-01-2016, 06:58 PM

i thought of maybe pulling just the #1 jug off and filing it down. but while i'm in there ..........
we all know how that goes

tharbert · tharbert's Garage

Drats! But, at least you found the problem. I dunno about the damage. I know what I would probably do...err on the side of caution as the engine's out of the car..

Rusty 356 · 12-02-2016, 10:39 AM

Do a leakdown on the cylinder. If okay, go for it.

till@frankfurt · 12-03-2016, 04:33 AM

In my opinion, the piston has been deformed and probably the top ring is stuck. This will lead to unsufficent sealing.

I would take a deep breath of fresh air, motivate myself and then pull the cylinder to check and modify the piston ring groove with a file.

WERK I · WERK I's Garage

If there is piston damage, you can bet the head took a hit as well. There's going to be an area in the combustion chamber that will develop hot spots, increasing the probability of pre-ignition.

Walt Fricke · 12-03-2016, 10:41 PM

Let me see if I have this right: an 8mm washer (steel? Aluminum?)fell into the intake port unnoticed. And then, as you hand cranked the engine at some point, it worked its way through the valve into the cylinder? Where you found it and fished it out, and we see it on the towel?

I don't understand what the other picture (or is it two pictures) shows. Is that a Borescope shot looking up inside the combustion chamber at the valves? Something else? I'm guessing Borescope because you say the cylinder wall does not look scored. What edge of what are you talking about? You say the bottom of the piston had some marks. How can a washer falling into the cylinder from the top with the piston in place damage the bottom of the piston? You can't see the bottom of the piston anyway, Borescope or no. So it is hard to know what damage you saw.

Till thinks the washer distorted the top ring land. If the engine was horizontal, the washer would lay flat on the down side of the cylinder, and as the piston rose it would compress the washer lengthwise between the edge of the piston and the head, more or less. That could account for the shape of the washer. Is that where you saw some distortion of the piston crown?

I'd not think an aluminum washer would damage the piston to that extent, but steel is more likely for intake manifold nuts and washers and that could cause more problems. The picture/pictures of what is inside just don't seem to show anything one can use.

I had six short 4mm screws fall into a motor on the race track. They had held the three carb air horns on that one side in place, and vibrated loose and jiggled in, one by one. My wife, who was racing, didn't really hear anything, but I did, standing in the pits - engine didn't sound right. Race ended a lap or two later. Some got spat out the exhaust, some were embedded in the tops of pistons, and maybe one in the head. After pulling the heads I cleaned things up with a file and put it all back together. Engine ran fine.

But I am surprised you didn't feel the resistance the first time you turned the crank by hand, with the plugs out, after it fell in. Had to have taken some force to bend that washer.

boosted79 · 12-04-2016, 06:56 AM

" My wife, who was racing,"

Where can I find one like that?

drola · 12-04-2016, 08:50 AM

Quote:

Originally Posted by Walt Fricke

Let me see if I have this right: an 8mm washer (steel? Aluminum?)fell into the intake port unnoticed. And then, as you hand cranked the engine at some point, it worked its way through the valve into the cylinder? Where you found it and fished it out, and we see it on the towel?

steel washer somehow fell in. fished it out with magnet. when? how? i'm not sure as i was very careful when i pulled the intake runners. also, i immediately plugged the ports with balled up paper towels to avoid this very thing

I don't understand what the other picture (or is it two pictures) shows. Is that a Borescope shot looking up inside the combustion chamber at the valves? Something else? I'm guessing Borescope because you say the cylinder wall does not look scored. What edge of what are you talking about? You say the bottom of the piston had some marks. How can a washer falling into the cylinder from the top with the piston in place damage the bottom of the piston? You can't see the bottom of the piston anyway, Borescope or no. So it is hard to know what damage you saw.

the pictures are of the bottom of the piston taken through the spark plug hole from two different angles. with the piston at the bottom of the stroke you can see the bottom of the head without any problem. the washer must have fallen in and gravity laid it at the bottom of the cylinder. when i turned the crank it pushed the washer up against the head and deformed it. thing is, i didn't force the crank to turn. once it felt like it wouldn't turn any more i didn't force it. from flipping the engine around on the stand, the washer must have moved because suddenly the crank would turn but at that one spot it would not turn smooth. almost like it had a spot of play or something.
also, by bottom of the piston, i'm referring to the bottom of the dome or head or whatever it's called.

Till thinks the washer distorted the top ring land. If the engine was horizontal, the washer would lay flat on the down side of the cylinder, and as the piston rose it would compress the washer lengthwise between the edge of the piston and the head, more or less. That could account for the shape of the washer. Is that where you saw some distortion of the piston crown?

yes, that is correct. i don't see how it would have distorted the top ring land as it wouldn't have made its way between the piston and cylinder wall.

I'd not think an aluminum washer would damage the piston to that extent, but steel is more likely for intake manifold nuts and washers and that could cause more problems. The picture/pictures of what is inside just don't seem to show anything one can use.

anything one can use? as in the piston is trashed?

I had six short 4mm screws fall into a motor on the race track. They had held the three carb air horns on that one side in place, and vibrated loose and jiggled in, one by one. My wife, who was racing, didn't really hear anything, but I did, standing in the pits - engine didn't sound right. Race ended a lap or two later. Some got spat out the exhaust, some were embedded in the tops of pistons, and maybe one in the head. After pulling the heads I cleaned things up with a file and put it all back together. Engine ran fine.

wow. gives me hope

But I am surprised you didn't feel the resistance the first time you turned the crank by hand, with the plugs out, after it fell in. Had to have taken some force to bend that washer.

i did feel the resistance. but i didn't force it. i think when i moved the engine on the stand the washer must have moved around in the combustion chamber and somehow allowed the piston more upward movement and somehow crushed the washer. maybe at the top of the stroke the piston put more force on the washer without necessarily more force on the crank (?)

Walt Fricke · 12-04-2016, 04:49 PM

Well - learned a little more: steel washer (the stock ones for the intakes are thin spring steel, aren't they?), hand turning, no special force, and even with the washer fished out, still a tight spot?

Your terminology is, not to put too fine a point on it, unusual. The crown of the piston is its top. That is the part which could be damaged. You could describe the part of head where combustion occurs as the combustion chamber I suppose (though this technically includes the top of the piston?), but here we all understand what you mean when referring to the part of the head which faces the top of the piston.

I am afraid the pictures don't help me at all - they look like the face of the moon. Was the Borescope lens pointed up to show the head? Or down to show the top of the piston? All I see is two round things (two separate pictures of the same thing?), and a sort of line angling across both. Borescope interpretation is tricky, to be sure.

Here are some suggestions: use your bore scope to inspect all of your cylinders to see if there are any foreign objects in any more of them. Assuming none, use the scope to inspect all around the circumference of the piston top to see if there is some kind of dent made by the washer. Use the bore scope to inspect all of the cylinder wall along its bottom (and, if you flipped the motor before fishing out the washer, its top) to see if there is any scoring. If you can use right angle Borescope mirror ends to do so, inspect the head, especially around what would be the bottom of the combustion chamber (and the top, if you had flipped the motor).

To damage a ring land, you would not necessarily have to have shoved the washer between the piston and the cylinder. If something pushes hard enough just on the top outer edge of the piston, it might force the aluminum in that area down just enough to bulge into the groove into which the top ring sits, which would pinch the ring, etc. I am a bit dubious about that having happened. And I don't think that would produce the hitch in your gitalong when turning the crank.

It is that unevenness, which I assume simply was not there before this happened, which seems of most concern. When the washer was in there, you had a clear physical cause of why it suddenly got hard to turn. You fished that obstacle out. Now what could cause an interference somewhere? A rough spot on the cylinder wall, which grates on a ring? Not too likely, as the cylinder walls are pretty tough, but I suppose a small raised area could have been created. If a gouge in the head stuck down toward the piston, maybe you could bump into that each time at TDC? Things might give (the piston can rock a tiny bit) each time you hit it. So is the resistance exactly at TDC? But if this is a stock motor, there is plenty of clearance there - if the washer had somehow stayed parallel with the top of the piston and flat, it probably wouldn't have damaged anything (of course it couldn't do that unless you had the engine on its side all the time on the stand).

Of course you don't want hot spots which could cause pre-ignition, but not every small imperfection is going to do that.

Wayne 962 · Wayne 962's Garage

I 2nd the advice of leakdown and/or compression (if you can turn the motor quickly using the transmission and the starter motor. If all looks well, button it back up. I don't see how a washer can get in there and damage a top ring - it probably just dinged / scratched the top of the piston and the head?

What's the worse case scenario? Compression loss once the engine is back together? So, then pull it and take care of it then. I wouldn't go fishing for more problems that may or may not be there?

-Wayne

tharbert · tharbert's Garage

Maybe this will help? I pulled a piston pic (prolly not Porsche but it works...) to help imagine what the bore scope pic depicts.

tharbert · tharbert's Garage

drola · 12-06-2016, 05:10 AM

just to clarify - the motor now spins free without any interference
what worries me is that the crown of the piston, where it is damaged, is extremely close to the cylinder wall. it has not scored it but i'm afraid that once it heats up and expands it will score the wall.
i think i'm going to just break down and pull it apart. the car has 136k miles on it and although it looks as though the motor has had some work done to it, i have no proof. so i'm thinking pulling the heads/jugs, put new rings, file that crown back to original shape, lap the valves, new 964 valve stem seals and put it back together. that is unless the valve guides need replacement in which case i'll do that too
major leaks aside, which were coming from the rocker shafts, the motor actually ran pretty well but it doesn't hurt to have a baseline

boosted79 · 12-06-2016, 05:36 AM

I would run it, what do you have to lose? Worst case you have to have that jug re-plated if the piston touches the wall but I very much doubt that will be required. Run it then do another scope on the wall.

drola · 04:24 AM

ok you guys convinced me. i started to put it together and will roll the dice. worst case is that it will need to come out again. second time on the same car is always easier since all the rusty and hesitant stuff has already been dealt with.
thanks for all the input and i'll report back in a few weeks with results. i'd love to get it done sooner but i'm having knee surgery next tuesday which will keep me out of the shop

WERK I · WERK I's Garage

drola,
Do what YOU think is best. It's your time, wallet and engine. You're there by the engine and everyone else is basing their opinion based on what you're telling them. Whatever you decide, good luck and enjoy.

strictly · 12-10-2016, 01:09 PM

the motor has 136k miles on it?

you can't just re-ring it, the P&C's will be deformed to match the rings, and being a 2.7 it might be alusil? which is debatable, but as i understand best not to re-ring whatsoever for alusil, so for P&C's I vote leave alone, or replace full set, or if nickasil, re-ring, with pistons checked/cleaned/bead blasted and cylinders checked and if okay renikasiled