Bad news from the stars

NKN · Apr 11, 2016

Draining motor oil, I had a surprise:

It felt from inside the engine, can somebody tell me where does this nut come from?

htown16 · Apr 11, 2016

Not good. Crank nut? Would have split the cases to find out.

pete.v · Apr 11, 2016

How's about some better shots of that nut?

zotz · Apr 11, 2016

Not a very good pic. As far as I an see it looks square. Sure it's not your transmission adjuster?

NKN · Apr 11, 2016

pete.v said:
How's about some better shots of that nut?

Ok, here we go:

Perhaps the most interesting ones:

What is very strange is, first, the direction of the black line changes; 2, that I cannot see the black line on one face of the nut when I'm looking with my eyes, even with a magnifying glass?!? Or when I took the nut back inside home :shock:

NKN · Apr 11, 2016

zotz said:
Not a very good pic. As far as I an see it looks square. Sure it's not your transmission adjuster?

If only, but what is it doing there?

swooshdave · Apr 11, 2016

And here I thought a little sparkly stuff in my oil was bad...

Holmeslice · Apr 11, 2016

It looks a lot like a head nut - one of the 5/16 x 26 nuts that are #9 or #10 in the torque sequence, because of its flat bottom.

Is it possible someone years ago lost a head nut while putting the motor together, it wedged itself in a nook within the engine/frame never to be seen again until now, and fell out into your oil pan when you jarred it loose opening the sump screen? That's the good scenario.

If it truly came out of your sump then I would open it up. The not-so-good scenario.

BritTwit · Apr 11, 2016

htown16 said:
I would say you are probably going to have to split the cases.

I'd say so, before the crank splits the cases on its own.
That sucks, but someone was watching over you sir.
You were lucky in the long run, you found it before an engine explosion.

Cheers.

gripper · Apr 11, 2016

You can't ignore that, especially if it may be a crank fixing nut. You have my sympathy but lucky to find it now and not at 70mph. You might want to buy a lottery ticket

pete.v · Apr 11, 2016

You might get away with pulling just the top end off to see if all is well with the crank fasteners and hopefully go with the good scenario. If you end up having to go deeper, well at least you'll have a good start on it.

For now, check what kind of fastener that is and what it might apply to. Crank? Rod end? Head? Base nut? Maybe you can rule out the crank and rod end nut. That would be awesome.

There has been more than a few occasion where I have almost lost a base nut down there, both when removing and installing the cylinders, due to the fact that you need to have some nuts in relative position as you do both operation.
A bit fiddly you know.

Oh, damn fine pictures.

N0rt0nelectr@ · Apr 11, 2016

It might very well be a nut from the crank. I agree that the best thing you can do is pull the cylinders and look at the crank to see if any of the nuts are missing. Keep us posted on what you find.

John in Texas

swooshdave · Apr 11, 2016

http://www.harborfreight.com/digital-inspection-camera-62359.html

Might be worth the bucks to poke a camera up there to see if there are any crank nuts missing. Plus it's an excuse to get one of these cameras. :mrgreen:

DogT · Apr 11, 2016

Rod nut is 3/8-26, crank nut is 5/16-26 on 750, check it.

Dances with Shrapnel · Apr 11, 2016

I like Holmeslices perspective as well as Swooshdave's suggestion. Get a mirror and a light or turn the motorcyle upside down or on its side to get a good look at what, if anything, is going on.

A couple of thoughts here are:

1.) If it were a rod nut I am pretty sure the engine would have given up the ghost on a heartbeat. At a minimum you would have heard rod knock shortly followed by a grenade sound.
2.) I am pretty sure if it were a crank cheek nut that it would have to cause some carnage on the connecting rod. I am not certain on this and somebody with more time and resources could check this with a crank and rods on a bench.

See and confirm what you can from the drain hole and if in doubt, lift (not necesarily remove) the barrel for a look and see.

ashman · Apr 11, 2016

I say crank nut, looks like one, if it is then no need for a camera, just pull the motor down and fix it, what else is coming loose inside of your motor, be a good time to see what else is happening inside your motor for wear and tear, it's the best way to find out is now.

Ashley

Dances with Shrapnel · Apr 11, 2016

In at least one picture the nut looks cadmium plated. Neither the rod nuts nor crank cheek nuts are cadmium plated. This is not to say a PO did not use cadmium plated nuts there.

Danno · Apr 11, 2016

My vote is crank nut and I think that burnished mark is from the flywheel zinging it as it lay in the sump. I doubt if there's any way to replace it without splitting the crankcases, so the camera job may give you the satisfaction of knowing, but the work is still ahead of you in any case (pun intended).

pommie john · Apr 11, 2016

The cam chain adjuster nuts look a bit like that, but I can't see how it would get to the drain plug.

Strip it down, it's the only way.

Ron L · Apr 11, 2016

Not a connecting rod nut. Those have a split lock ring on one end (single use nut). It does look like a crank/flywheel nut. That would be the only possibility for a nut that belongs in the engine. As Kenny suggests, it could be an extraneous nut that was left there during the last rebuild. Pulling the head and cylinders will let you see if a crank bolt/stud nut is missing.

Bad news from the stars

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