What amount of metal particles is the norm for a small block after about three months, which has about 120,000 miles already on it? I changed my oil last night and I noticed some metal particles on my magnetic drain plug and was wondering if it was excessive or not. I understand there will be some because engines (even 305s) don’t last forever, but I was wondering how much is too much and how much is normal. Thanks!!!

 

not much, you'll see a little on the magnet. the bearings wear but aren't goingto stick to the magnet and thats what i'd be most concerned about

 

How come the bearing particles don’t stick to the magnet, are they not ferrous? So what’s the little bit of metal coming out of my engine when I change the oil?

 

I dont think bearing are made out of iron. Iron is ferromagnetic, there's only a few elements that are.

A bit of metal on the drain plug is quite normal, even new cars will have it.

 

without digging out a metallurgy book i think iron is the only element that is feromagnetic, nickle and colbolt are magnetic as well, but not feromagnetic. one big thing is that even though nickle and colbolt are considered magnetic thay can't be inspected or tested magneticly, or magnafluxed as most people call it

 

It's spelled cobalt.

 

Engine bearings are made of babbit, a lead/tin alloy & are non-magnetic.

 

Cobalt and nickel are ferromagnetic (at room temperature at least).

 

There's three ferromagnetic elements.

 

damn now i'm goingto have to look i thought iron was the only thing considered feromagnetic, even thought severl other elements were magentic.

 

ok found it on page 48 of Practical metallurgy and Materials of Industry 3rd addition by John E Neely "most ferrous metals such as iron and steel are magnetic, but most non ferrous metals are non magnetic. an exception is nickel which is non ferous but magnetic." on page 60 in the section on cobalt to paraphrase it says cobalt is non ferrous but magnetic below 2128*f. so it can't be non ferrous and feromagnetic right?

 

Yes they can be non ferrous but ferromagnetic. Ferromagnetic doesn't mean they have iron in them.

 

guess i'm slow to catch on but i'm going to go with what a metallurgy proffesor wrote in a book on the subject, unless someone can cite a source for their information

 

Sorry to divert the conversation away from subatomic gravitaional fields and structure, free ions, covalence, proton orientation, and general molecular theory, but I think the poster was asking about lubrication contamination.

But just to confuse the matter a little more, I was under the impression that common engine plain bearing shells also contained cadmium, beryllium copper, and other trace elements long with the tin and lead. Then again, I don't make them so what do I know? Everything changes.

And for more confusion, you'll always generate some ferrous particles from timing chain and sprocket wear, a little from cam lobes and lifter faces (even rollers will shed particles), lifter bores, ring wear, cylinder wear, some from the cam/distributor gears, rockers and pivot *****, push rod tips, valve stems, valve guides, etc. On top of that, oil in the crankcase that develops acidic properties from moisture contamination can leach iron molecules from anywhere within the case and oil pan.

There will always be some metal in the oil. The key is to determine the size and number of the particles and their material makeup to help determine their origin. Unfortunately, judging this with the naked eye is hopeless, and the surest way is with an oil analysis with a particle count and spectrographic scan. The particle count alone will not be a true indication since all particles will be measured, not just the metal ones.

If you feel that you have a serious wear issue, you'll need to recover the next oil drained from your engine in a pristine clean container, along with anything stuck to the drain plug magnet, then send a well-mixed sample for analysis. It's generally about thirty bucks to get a full test battery.

Incidently, new engine oil that is supposed to be "clean" typically has 60+ particles/ml. S.A.E. (automotive) oil standards are really disappointingly low, which is just another reason to use a good quality synthetic. ISO standards for clean oils typically list 16/ml as a maximum limit, or about four times cleaner than SAE "clean" oil. And you wonder why I'm not all that keen on SAE lubrication standards? Then again, I'm one of those guys that "wastes" money on synthetics.

 

I saw it on jeopardy. They asked for one reference of a ferromagnetic element. Contestant said iron, so I don't know the other ones.

 

From: http://www.ee.surrey.ac.uk/Workshop/advice/coils/mu/

Diamagnetic and paramagnetic materials

Fig. MPA b) above is the magnetization curve for materials classed as diamagnetic. In diamagnetic substances the flux grows slightly more slowly with the field than it does in a vacuum. Examples of substances which show diamagnetic behavior are ammonia, bismuth, copper and hydrogen. The decrease in gradient is greatly exaggerated in the figure - in practice the drop is usually less than one part in 6,000. Diamagnetic substances are repelled (very feebly) by an ordinary bar magnet. Diamagnetism occurs in materials whose atoms have only paired electrons.
Fig. MPA c) is the curve for materials classed as paramagnetic. Flux growth in this case is again linear (at moderate values of H) but slightly faster than in a vacuum. Again, the increase for most substances is very slight. Oxygen, tin, aluminium and copper sulphate are all paramagnetic and are weakly attracted to a bar magnet. The paramagnetic effect is often inversely proportional to temperature. Paramagnetism occurs in atoms having one or more unpaired electrons.

Although neither diamagnetic nor paramagnetic materials are technologically important (geophysical surveying is one exception), they are much studied by physicists, and the terminology of magnetics is enriched thereby.

Ferromagnetic materials:

The most important class of magnetic materials is the ferromagnets: iron, nickel, cobalt and manganese, or their compounds (and a few more exotic ones as well). The magnetization curve looks very different to that of a diamagnetic or paramagnetic material. We might note in passing that although pure manganese is not ferromagnetic the name of that element shares a common root with magnetism: the Greek mágnes lithos - "stone from Magnesia" (now Manisa in Turkey).