Found a chunk of metal after oil change on my M923A1

[Spiralout]

Does it smoke excessively, significant blow-by, how is oil pressure?

if oil pressure good, how is power? If all is good, you could take compression readings on cylinders to confirm rings are good.

It's running right now, oil pressure is 65-70psi at 140 degrees. No smoking after it warms up, there is a little while it's cold. I'm not familiar with how to test blow-by. Power seems good to me after it's warm, but I don't have another example to compare it to.
Here's a video of what it sounds like, not sure if this will be helpful. Engine was at about 120 degrees when this was taken, it gets quieter at normal operating temp http://vidmg.photobucket.com/albums...loads/2015-11/20151108_124600_zpsbvl88asq.mp4

 

[wcuhillbilly]

sounds ok,,,,,, but the video is only sound,,,, Most guys on here post it to Youtube for easier linking to the post...

 

[WillWagner]

It is a bearing or bushing. The engine sounds good, so a rod should ruled out. it could be a main bearing, after it warms up, look for heavy smoke out the breather, it will smell burnt. Sometimes an 855 will run with a spun main and have no noise. It could also be an accessory drive bushing or a compressor bearing. Does the engine have a new, unpainted compressor or the component directly on the front of the compressor? If so, it could be leftovers from a failure that has been repaired
Also, just for future reference, the C series in the 5t trucks have a different bearing composition than an 855. When the rods or mains spin it soes not extrude copper like the 855 does but rhe compressor will.

 

[Spiralout]

The compressor and attached parts are all black like the engine. I'll check to see if I can tell if it's newer than the other components. I've never seen the truck smoke excessively, only small amounts when cold.

All this learning is dangerous, I'm already plotting to build some sort of gantry crane to get the engine out if I have to!

 

[swbradley1]

If it is a main or rod bearing can't they be replaced in-frame?

(No, I don't know which is kind of why I'm asking.)

 

[wcuhillbilly]

Yes you can do an inframe on an 855 depending on what exactly is needed... Ive swapped out the mains and rods (bearings) on a few worn out small blocks inframe, by using some banding strap to gently tap the upper bearing around the crank to snake it out.. Or,,, drop the crank via straps through the cylinder holes.... but that requires dropping the trans too,,,, big PITA no matter how you go about it..

 

[WillWagner]

If a bearing has spun, the crank is junk. The smoke you are looking for will be coming from the blow-by tube, not the stack. Replacing a crank in frame is more work than pulling the engine. the complete engine needs to be suspended in place, trans, flywheel housing and the complete front end need to come apart.

 

[Spiralout]

My searches are turning up empty, where might I find the blow by tube? Engine is warming up.

 

[AZK9]

I'm not 100% certain this will help, but I don't think there is always going to be an actual "blow-by-tube".

Not being a mechanic, but having read a lot recently... I think that the term 'Blow-By' pretty much means that when engine rings, pistons and cylinders get worn down, a certain condition occurs. This condition happens when the air/fuel mix get compressed and combustion happens. When the resulting gases are blown past, or by the rings and pistons they can go into the crankcase. Once inside the crankcase, pressure can blow oil and/or smoke out of any weakpoints. Sometimes it's the slobber tube, oil fill cap, dipstick hole, or places like that.

I think 'blow-by' is more of a condition that can cause smoke, or oil drip wherever it can find a way out of the engine. Again no expert here. But, hope that helps a bit.

 

[MtnSnow]

The blow-by tube aka "Slobber tube" will be connected to the valve cover and go down below the engine and is usually cut at an angle.

Edit. Here is a picture of the tube (it's the item to the rear of the engine and runs down next to the bellhousing
http://www.hommeles.com/upload/xlarge/p1040243.jpg

 

[Bandit02]

Looks like a piece of the thrust bearing for the crank.

 

[Spiralout]

Nothing at all was coming from the slobber tube, and doesn't look like it has for a long time.

 

[JohnnyBM931A2]

I still wonder if it really was just something left in there after a previous repair.. I mean, you'd think they would clean everything out, but who knows.

 

[Spiralout]

I think you're right. This is the only indication of a problem I've ever seen. I'll change the oil again at an accelerated schedule and see if anything more comes out.

 

[AZK9]

... This is the only indication of a problem I've ever seen. I'll change the oil again at an accelerated schedule and see if anything more comes out.

Seems like a reasonable plan. Keep us posted.

 

[WillWagner]

Looks like a piece of the thrust bearing for the crank.

No

 

[74M35A2]

Keep driving it. You'll eventually find out what it is.

 

[mdmorgan]

That's not a chunk, these are chunks, lol. Oh and breezing through the thread I saw someone ask if the pistons are aluminium, they are.