Copper flakes in oil

[Dan Epperly]

I rebuilt my engine about 12k miles ago.
My first few oil changes had the usual bits of metal from break in, all of which has gone away except I am still getting A few copper flakes.
I can't figure out the source. The main bearings don't have copper in them, nor do the rod bearings..
I ground the side of a used set of newer rod bearings and don't see any copper, so I don't think that is the source. The distributer drive is brass as are the valve guides and the wrist pin bushings.
I removed the flakes from the oil and they are clearly copper unless brass discolors in the oil?
Before I tear into it, I would like to know what to look for...

[Don Gale]

Are you sure no copper in the rod bearings? I'm in the middle of a rebuild and most of the rod bearings show signs of the outer layer worn thru to copper. Typical rod bearing construction is a steel shell, clad copper inner bed, and the journal surface coated with an aluminum-tin alloy:



Could be several causes of your finding copper flakes. I would send a sample of your used oil to a lab to have it analyzed. Depending on your level of risk, you could remove the strainer and wipe out as much of the inside of the case as you can reach, change the filter & wipe out the cannister, and fill with fresh oil and drive again for a few miles and drain into a clear glass baking dish. Maybe 2 iterations. Drive it gently again for a few dozen miles and repeat. If you find more flakes, time for a teardown.

Another source could be the distributor drive gear, but it is brass or bronze and you should be able to visually distinguish it from copper.

[Norm Miller]

Probably swarf left over from pre-rebuild likely came from original rod bearings.

[Wes Bender]

You do have a full-flow filter don't you? Are the flakes showing up on top of the bypass filter?

If they're on the bypass filter, they're also throughout the engine. I wouldn't drive it until you can be sure where the stuff is coming from. Don't turn a $1000 problem into a $5000 or $6000 one.

[Dan Epperly]

I know the original rod bearings had the copper core, but when I ground through the newer one there wasn't any.
I had the case cleaned out, the old rod bearings weren't worn down that much, but yeah, you never know right?
I didn't see any copper on top of the bypass...I syphoned it out, wiped the bottom with Scott towels but didn't find any there.
If there was copper in the rod bearings i would have thought I would have found a ton of grey metal flakes from the rod bearings because it would have had to wear through that first. But that is not the case.
I wiped the inside of the case with paper towels and found no metal.
Engine runs great otherwise.
I did not full flow it...yeah, I know.
I will tear it down.

[Jim Liberty]

Dan, better safe than sorry. …...Jim.

[Dan Epperly]

Dan, better safe than sorry. …...Jim.

I'm just sorry i have to tear it down!

[C J Murray]

Copper? Or brass from the distributor drive gear?

[C J Murray]

Coating from valve spring shims?

[Norm Miller]

CJ probably wouldn't be flakes from the brass dist drive gear? More likely gold dust.

[Norm Miller]

CJ probably wouldn't be flakes from the brass dist drive gear? More likely gold dust.

[Ron LaDow]

Regardless of what it is, the bearings are not going to like it, and relying on that 7% filtration rate means they're going to get a whole lot of it.

[Dick Weiss]

Going thru the real bearing surface material will get to the copper, and if it wears continually, the oil pressure will go lower and eventually will "spin" the insert(s).
Only the original 50, 50, 50, 40 A/B main bearings are full aluminum. (except the late steel-backed bearings from------?) All rod bearings are steel-backed.

[John Weyand]

Some years ago I had a similar issue with a VW engine that my son and I rebuilt. What we eventually found was a valve guide wearing excessively due to misalignment of the rocker. The valve stem was cutting into the guide and leaving "gold dust" in the oil.

[C J Murray]

Some years ago I had a similar issue with a VW engine that my son and I rebuilt. What we eventually found was a valve guide wearing excessively due to misalignment of the rocker. The valve stem was cutting into the guide and leaving "gold dust" in the oil.

Hi John. Did the finish on the valve stems have anything to do with that?