while a gentle use of compressed air for chip clearing on a mill vise is used, we don't blow off chips from machine ways here. We do precision work here and want to keep it that way. If you are repairing farm equipment however, that may be different. Different practices for different environments.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

I don't do this often, but I've got to throw in with PEH here until he starts hastling me about this thing being an engine and not a motor. You've got a big old hole there where the pre chamber came from. If it were my car, I'd attract what I could with a magnet and crank the engine to blow the rest out. We are not working on the propulsion gears of a nuclear sub here. The gears on an American sub are made to such close tollerances that they are virtually silent which is why we were able to shadow Soviet boats on entire patrols without them efer detecting the presence of an American sub. My point is that we are working on a tough old diesel engine. I don't think a few metal shavings are going to be a real problem. For me compressed air, vacuuming, or engine cranking would all be fine.

Peter

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Peter, In general I agree with you....
However, I once figured up the number of revolutions which my volks made on a trip from Dallas to Houston... it was something like 2 million revolutions in five hours ( of course the number of strokes was twice that)... I was shocked.. if you have something hard enough to be wearing on a part it is next to the shear number of strokes can sure add up...
In India there are craftsman who cut gemstones by running a wire back and forth just dropping grinding dust on it... and finally it works.... obviously this is not a place of high labor costs... but you get the idea.....
Anyway, James asked, and these logic and physics discussions don't just apply to the question at hand.... I am sure a few people learned something about some future action by this discussion... or perhaps just how stubborn some old guys can be....

So what you are saying is that regardless of the fact that thousands of explosions caused by expanding gasses and swirling turbulants created by exhausting gasses occured on that trip, a little metal shaving was tenacious and didn't budge from its little hiding spot. Amazing.

Peter

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Once you get something between the piston and bore , for example, you have NO NEGATIVE PRESSURE FORCES with which to expell it...
The exhausting of gases is from the upward movement of the piston ... and thus is also a downward force on the area around the side of the piston.. which keeps anything at that location locked in place...
I can't believe a grown man would throw me such a softball ... of course it makes more sense after your derivisive comments about me following the Factory Shop manual...

That's quite true but the laws of physics still apply! everything in the cylinder including any hypothetical particle between the piston and bore has kinetic energy.
When that piston travels up at a high rate of speed and does it's about face there is no attraction between our hypothetical particle and the piston/bore.
In fact the laws of physics state that an abject/particle in motion will stay in motion unless acted upon by another force. So as long as the only force acting to keep our imaginary particle attached to the piston while it's flinging up and down is gravity. A relatively week force I may add. Then our imaginary friend should be expelled from the cylinder rather quickly.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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It appears that the tip of the glowplug is very soft metal. At least the ones in this car are. Also as a side note, the 'shavings' aren't remotely magenetic. I managed to work a magnet through the hole and withdrew nothing at all.

I'm not sure what the tip of the glow plug is, but its not very magnetic (even one of the others that wasn't damaged.) The glowplug appears to be a thin sleeve of aluminum perhaps, that is surrounding something else. In fact it seems like a powder. I tried to take some pictures last night, but frankly they all came out horrible. For some reason my camera wouldn't focus properly.

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'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.

well, hopefully you can get a plastic tube in there hooked up to a vacuum before you turn the engine over. If you slice the end of the plastic tube a number of times at the end, this might make a cheap "brush end". Either way, it's worth a few minutes IMHO to try to vacuum up particles. If it were my engine, I would. Good luck!

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Diesels do depend on extremely high compression pressures to run. And a scored cylinder can cut your pressure drastically, resulting in a cylinder that is "worn out". So I do agree that it is necessary to remove all the metal particles. I'm saying that a high pressure air blast directed into the cylinder, and then directly at the crack between the cylinder and piston should remove all the particles.

I also agree with the idea of cleaning the cylinder then turning the engine to lower the piston and see if there is anything else stuck to the cylinder.

" I'm saying that a high pressure air blast directed into the cylinder, and then directly at the crack between the cylinder and piston should remove all the particles."

We are talking about matter between the piston and the bore above the top ring...

Have you seen the demonstrations of air pressure which people like ' Mr.Wizard' put on ... like wetting two pieces of glass and trying to pull them apart ? The problem with pulling them apart is that ONE side has NO air pressure against it... and the other side and edges have approximately 15 POUNDS PER SQUARE INCH...

When you direct that air blast into the cylinder HOW DO YOU GET THE PRESSURE BEHIND THE PARTICLE... SO THAT IT IS EXPELLED FROM THAT NARROW SPACE BETWEEN THE PISTON AND BORE ? Otherwise you have the same pressure all around it keeping it from coming out of the narrow confine...and no pressure behind it... thus holding it into place...

Most top rings on pistons are not flat.... they slope so that pressure from above presses them outwards to help in maintaining contact with the cylinder wall... so most likely any junk will be forced to behind the ring.... then only taking out the piston and taking the ring off would afford a way to clean it...

James, the tip is probably something like Tungston... like light bulb filiments...
the powder is probably ceramic... which provides heat conduction away for cooling while providing electrical insulating properties at the same time... and which would powder when crushed...

"In fact the laws of physics state that an abject/particle in motion will stay in motion unless acted upon by another force."--Danny

First, those pistons travel fastest at mid stroke... and slow down to almost no movement for several degrees of the crank at both top and bottom of the stroke... which is why determining the TDC using the piston travel is a matter of measuring and marking several degrees before the top and finding the same distance the other side... then just taking half way between those spots to call TDC..

But concerning the above quote.... you have left out air pressure. That is the OTHER force.... and it rules the day down in that bore... even more so on a turbocharged engine...

Some of you guys think and worry too much. Wax on wax off. Grasshoppers go through life without undue burden.

Peter

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I wouldn't have a problem with compressed air being utilized if one would be able to blast the compressed air around the periphery of the piston to free any trapped debris. Since this is effectively impossible without pulling the cylinder head, the use of compressed air will certainly remove the majority of the debris, however, there is some risk that the swirling air could drive some small debris between the piston and the cylinder wall.

I do agree that there is little risk that this debris will jam itself to such a degree that it will imbed itself in the piston, but, it's not impossible. If the debris gets caught between the ring/cylinder/piston on the upstroke, it could imbed itself in the piston and proceed to do damage to the cylinder until it wears away, or the cylinder wears away.

Please note, however, that a piston clearance of .001" won't allow much of a partical size, and, therefore, such a particle cannot do much damage to the cylinder wall (maybe a vertical groove that is .001" deep). So, even if the worst occurs, the engine will not be unduly harmed.

If it is possible to vacuum out the debris, rather than use compressed air, the risk of causing a trapped particle is lessened. However, this presumes that you can thoroughly vacuum all the debris out of the cylinder. If you cannot do this, the use of compressed air might be necessary, even though it entails some additional risk.

ditto the above posts on methods to clean. suction air ...i wouldnt use oil. no sense obsessing, just do the best you can to clean and hope for the best. if there is anything trapped in there the only alternative is a teardown anyway. doesnt make sense to tear down for a feared problem only for a real one.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.