Small weld repair to 4340 Crankshaft?

[LJJJBAWO]

I am looking for advice on the best procedure to follow when making a very small weld repair to the journal of a 4340 crankshaft. It has only one very small mark that won't clean up at .020. The weld would probably take only 10 seconds or so. Just wondering the best filler to use and if a weld that small will require and heat treatment. Thanks!

[Momus]

I am looking for advice on the best procedure to follow when making a very small weld repair to the journal of a 4340 crankshaft. It has only one very small mark that won't clean up at .020. The weld would probably take only 10 seconds or so. Just wondering the best filler to use and if a weld that small will require and heat treatment. Thanks!

Photo of small mark?

[LJJJBAWO]

the spot circled in red. I think the rest will clean up grinding .020 under. Like to hear everyone's thoughts. Thanks.

Crankshaft.jpg

[Tom Walker]

Are you sure that is going to clean up at all? Looks like there is all kind of damage, but again, a photo is difficult to make an accurate assessment from. Good luck though.

[Dave Koehler]

Fixed a few like that if they passed the mag and straightness tests.
TIG it up, grind it and drive on.
OR
Leave it be and look at it as an oil reservoir.

[Tom Walker]

Definitely like the oil reservoir approach:)

[racear2865]

Definitely like the oil reservoir approach:)

I also have repaired my share of them. Make sure it is not cracked before u weld. And make sure you penetrate. Do not get a cold weld.
reed

[LJJJBAWO]

Dave, thanks for the reply. It is not my crank. Belongs to a friend, stroker crank for a 440 mopar. He asked if I could weld it. I am not sure if welding it up and grinding it out is the best option or if it should just be blended out and left. Not sure what effect it would have on the oil film strength with a low spot on the journal.

[Baprace]

Definitely like the oil reservoir approach:)

I also like the oil reservoir , you are not stressing that area with hot weld and cold crank

[econo racer]

How much would it cost to send it to the crank manufacture and let them fix it?

[1972ho]

Mile high crankshaft in Denver would charge you 250.00 to weld it and grind back to whatever it is.

[LJJJBAWO]

I am on the east coast of Canada, a long way from anywhere!

[1972ho]

Yep that would be costly just in shipping but the guy is good with what he does.

[PackardV8]

FWIW, the first SBF 302" I built, back when they were a new thing, had a casting void almost that large on the surface of one journal on the OEM crank. I was ready to reject the crank, but even at that young age, I thought to examine the bearings; there was no sign on them from thousands of miles of having that "oil reservoir" on the crank surface. The crank is still running in that Sunbeam Tiger today. Your friend's results may vary.

[Krooser]

You should be able to find a competent machine shop/crank shop in eastern Canada. Look at shopd that cater to class 8 truck engines... likley they can handle it or know of a shop that can.

I've had numerous cranks repaired/welded/reground over the last 50 years without any need for nitiding afterwards.