Topic: uh-oh: ferrous metal grounds in oil filter; advice appreciated!CB750K2 more pix

[ksteve]

100 miles after an oil change, I drained the oil and opened the filter.
It was depressing.
I found this:



and this:



I put a magnet to the grounds. It mostly seems to stick, so it's mostly not aluminum.
It's all pretty small stuff:



The specifics:

-I bought this '72 cb750k2 recently after it had sat unused for 35 years. 19,000 miles on the odometer. PO said it ran fine before parked around '87.

Oil-related tasks I did before starting:

-Drained oil, removed filter, dropped oil pan, removed oil tank, cleaned out sludge;
-Saw no metal shavings anywhere;
-Dropped oil pump; nothing caught in screen;
-Primed pump, put in new o-rings, re-installed;
-Added 10W-40;
-Adjusted cam-chain tensioner;
-Set tappet gaps;
-Kicked slowly 20 times, then cranked starter with kill switch off; oil light went out fairly quickly;
-While cranking, checked that oil flowed from behind #1 and #4 exhaust tappet covers and behind oil-gallery plug on right side;

Starting the first time:

-Kill switch on: engine started in 3 seconds and ran well; the normal tappet and cam-chain noise; no unusual sounds;
-Drove gingerly for 20 miles, then more aggressively. Engine runs well. No change in sound;
-Oil light goes out within 1-2 seconds of cranking.

Is it possible that something inside an engine changes as it sits 35 years to block oil passages? A rotted rubber bit? Sludge?

Or did I do something wrong? (Maybe I should have left the pump well enough alone?)

I assume this means I need to take apart the engine. Should I check anything before I do, to narrow down the problem?

Oh, and any words of encouragement greatly appreciated! This is a major bummer.



Thanks,

Steve

[dave500]

surface rusty bores?dont worry too much about it,see how it runs,if its not blowing smoke itll be ok,have a look here.
http://forums.sohc4.net/index.php?topic=103432.0#lastPost

id drop the sump again just to check if any larger bits are around.

[ksteve]

Thanks, Dave500!
It's not blowing smoke at all. Can I assume the filter caught this before it circulated in the engine and ruined other stuff?
(good idea on those hard-drive magnets)

[Teatimetim]

Not necessarily a bad thing, long sit means rings maybe reseating.

[Toxic]

See if it is a repeatable event.  Finish your oil change and check again after another 100 miles.

I would be more concerned if it happened again

[lucky]

It is not good and the sooner you take it apart the more money you will save.
Check the clutch first because if it is the clutch then you won't have to take the engine apart.

[trueblue]

If the bike has been sitting for many years what comes out in the first change is essentially irrelevant, what comes out on all the subsequent oil changes is relevent.  If the metal shavings get gradually less and less, then you have nothing to worry about, if they stay the same or increase then you may have something to worry about.  All this is thrown out the window if there are any untoward noises coming from within the engine.

[ekpent]

Since it is steel or magnetic I would be thinking it may be more of a tranny/gear thing possibly. Is it shifting smooth and staying in gear.   Big globs of aluminum can be even more scary.

[ksteve]

Since it is steel or magnetic I would be thinking it may be more of a tranny/gear thing possibly. Is it shifting smooth and staying in gear.   Big globs of aluminum can be even more scary.

Tranny shifts smoothly and stays in gear. There's an occasional false neutral (between 3rd and 4th, i think), and it's sometimes hard to get into neutral when stopped with the engine hot. Are there any diagnostic techniques to see if it's the transmission without cracking cases?

[tlbranth]

Nothing to worry about? Are you kidding? Something big is wrong with this engine and the problem needs to be found before running the engine any more.

[trueblue]

There are numerous reasons for there to be metal shavings in the oil and most of them are no reason for alarm.  The biggest one is how do you know the oil changes were done on time in the past.  If it had been left in there for way too long in the past, for example if the oil hadn't been changed for 10k miles then you would expect for there to be a lot of shavings in the oil, especially if the bike had sat for a long time after.  The sludge that would have built up in the oil over time would settle out while sitting and take a little while for the detergents in the new oil to clean out.  Like has been said before, check it again after a bit more riding, if it gets worse then worry, if not count your blessings.

[ksteve]

Thanks, all, for your advice, which is much more optimistic than I expected!

I pulled the pan and took some pix that may or may not tell us more. Any more thoughts?


This is all that was in the pan--a few flecks of metal, some pieces of black flexible stuff (rubber?):



The biggest of the black bits:



The oil pump screen:

[trueblue]

It's a little hard to tell just from picture.  Is that black stuff flexible like rubber?  As in no matter how far you bend it it will flex back, or is it only slightly flexible?  As in it will only bend a little then breaks up, and it will also break up if rubbed between your fingers.  What it looks like is the sludge left behind after an engine with a wet clutch in it has been run for a long time on old oil then parked for years, if this is the case then the black stuff will break up like mentioned above.  If on the other hand it holds together, then I'm not sure what it is, it may be silastic that was used in a previous tear down, or something else.

[ksteve]

It's a little hard to tell just from picture.  Is that black stuff flexible like rubber?  As in no matter how far you bend it it will flex back, or is it only slightly flexible? 

Yes, flexible. Bends way over, then flexes back. There's not much of it in the pan. Microscopic bits of it in the oil filter (you can see them it the pix in the first post). The bulk of the mess is the metal.

[Harsh]

The rubber bits are probably your primary chain tensioner or possibly your cam chain tensioner rollers.  If it is the primary chain roller I don't think you can replace it without splitting the case.  You can pull the head and check the cam chain tensioner roller.  Look at the wheels and if you see chunks missing off of them you have found the culprit.

[Toxic]

If it were part of the tensioner or the roller it wouldn't be as flexible as described.

I tend to agree with left over silicone from a prior engine job.

Can you see telltale signs of silicone between the seams with you look at the engine?

[ksteve]

Can you see telltale signs of silicone between the seams with you look at the engine?

Yes, there are some globs around the seams. I'll have to examine it more closely when I get home.
In the end, what worries me most is the metal. Here's a shot inside the oil tank, showing glittering bits:

[dave500]

you could remove and flush the tank and lines,for peace of mind you could remove a rocker cap one each end then with the motor running you should see oil splashing around.

[ksteve]

you could remove and flush the tank and lines,for peace of mind you could remove a rocker cap one each end then with the motor running you should see oil splashing around.

Yeah, i did the rocker-cap thing several times and saw oil splashing.

The funny thing is that there's almost no metal in the pan, where you'd expect to see it if the engine or tranny were shedding steel.

Since all the oil that goes through the engine and transmission then goes to the pan (before hitting the scavenger side of the pump), you'd think there would be at least some metal sediment there in the oil pan.

The fact that all the metal is in the oil filter (fed by one side of pump) or oil tank (fed by the other side of the pump) would almost seem to suggest that the metal it comes from inside the pump, no? Or would the pump suck it all up all that metal through the screen without leaving much behind?

[dave500]

theyre fairly fine and pass that screen,ride it some more and open the filter again and guage wether its less this time,if the motors got oil up top and no real noises itll be ok i think,that black stuff if you can stretch it its silicon from a po.

[Kevin D]

Can I assume the filter caught this before it circulated in the engine and ruined other stuff?

You can check this yourself. Open the oil galley cap above and left of the points cover (engine off!). It ought to be clean.

I have found debris in my filter before but never anything like what you have there. Wash that oil tank out as well.

[ksteve]

Open the oil galley cap above and left of the points cover (engine off!). It ought to be clean.

I have found debris in my filter before but never anything like what you have there. Wash that oil tank out as well.

galley seems clean inside.

theyre fairly fine and pass that screen,ride it some more and open the filter again and guage wether its less this time,if the motors got oil up top and no real noises itll be ok i think,that black stuff if you can stretch it its silicon from a po.

I'll do that. Maybe ride for 10 miles and open filter. I assume I can open filter without draining the pan (since filter is fed from pump)?