Blemish on Rod Journal

Superman · 03-04-2002, 10:43 PM

Got another thing to worry about. Don't know how I missed it (hope I was not the cause) but there is a blemish on the #6 rod bearing journal. Right beside one of the oil holes (if the journal turns North and South, this thing would be East or West of the hole) there is a semi-rectangular patch, about 4mm x 7mm that is not only discolored, it is rough! Like corrosion. From some angles it is a dark color. Around it there is also some discoloration, perhaps a square inch altogether and one other tiny spot that is also rough.

the discoloration pattern looks like a liquid made these tracks. I should have a good magnifying glass but I don't. Still, it looks like corrosion to me and I can feel in with my finger. rubbing does not take it off at all.

The rest of the journal looks perfectly beautiful, like all the others, and the matching bearing shells look the same as all the others. Anyone have an idea what this is and how to deal with it. I suppose I take it to a crank guy and see if it can be polished out. I sure hope I didn't get something on this to cause the blemish, but maybe I did because this roughness would have worn against the bearing, it seems to me.

critter · 03-05-2002, 05:28 AM

You didn't have any metal prep around your crank by chance did you?(Phosphoric acid)

Superman · 03-05-2002, 05:40 AM

No. I've used MEK, carb cleaner, brake cleaner and alcohol in the last six weeks. Nothing corrosive.

These marks actually look like a solvent with dark crud suspended in it got on the journal, flowed around a little and then dried and left the crud behind. But the trouble is, it does not want to be cleaned off. I have used MEK, which seems to clean just about anything, and this blemish is not coming off at all.

Leland, how can I track down that guy in Boise who recognized your crank and told all those stories. I think I need an expert here if this blemish is corrosion. What could do that?

Early_S_Man · 03-05-2002, 11:51 AM

Super Jim,

What did the rod bearing you took off that journal look like? If that spot was etched by a globule of acid rain created inside your crankcase, it will be below the level of the surrounding smooth, polished journal. I have the feeling that you could polish it out with a strip of ultrafine industrial Scotchbrite

Leland Pate · 03-05-2002, 09:45 PM

Hey Jim,
I have no idea what you have without seeing a picture.

But you are in luck!
I happen to have Toms business card in my wallet still!

I sent all of my stuff to Tom Franks Precision Crankshafts in Boise, ID.

He runs a small "one man" shop.

This is the guy who instantly recognized my crankshaft as that of a 3.0L Porsche about 32 milliseconds after looking at it.

Real neat guy... used to do all crank and rod work for Andial in CA.
...but trust me...he'll tell you aaaaalllllll about it... the man loves to talk.

Very reasonable and does outstanding work!

Precision Crankshaft
597 E. 44th St.
Garden City, ID. 83714

The phone number is:
208-321-8134

Good luck Jim!

Superman · 03-06-2002, 12:05 AM

Awesome, Leland. I'll set aside considerable time and place a call. I remember the story quite clearly. He even told of some folks shopping for a 917 crankshaft. Talk about a hard-to-find part! The boys in Germany refused to believe someone seriously might be looking for a 917 crank. Largely out of sheer confidence (some might say arrogance) in the crank itself. Apparently, a 917 crank is a thing of incredible strength and beauty. I think I recall that it is FULLY POLISHED, not just the journals. Now that would be something to see, truly!

Anyway, I no longer think my crank might have damage. I think something just got on it, perhaps something quite hot spilled on it while I was playing with fire and head studs. Tomorrow evening I will polish it with some 1500 grit emery paper.

Thanks to all....you know who you are.