964 Engine Case Composition

[drola]

I need to have a small weld repair on my 964 motor and the welder is asking me if I know the exact composition of the case.
I know it's aluminum, but does anyone know if there is some sort of mix in there? Like possibly a certain amount of magnesium or any other material that the case is composed of other than straight up aluminum?
Cheers

[mb911]

Well the welder should be able to choose the correct wire if they are a truly expert welder. I have been a welding educator, instructor, state weld test conductor and CAWI for 24 years. My suggestion would be 4943 it’s not mainstream but does excellent with expansion and contraction during welding heat/cool cycle with less likely to propagate a weld crack.

I will tell you this just because a person has a welder and can perform welds doesn’t make them the right person for the job and they may not have the background knowledge to perform a proper weld on a multi thousand dollar engine case.

[Duc Hunter]

Just curious, if we hand a welder an unknown metal how do they choose the wire? Or an unknown alloy?

[mb911]

Originally Posted by Duc Hunter

Just curious, if we hand a welder an unknown metal how do they choose the wire? Or an unknown alloy?

Most times experience tells the story, metal analysis gun, research, chemistry test, etc. again just because a person can weld and owns a machine does not make them a professional. It’s like just because I can mow my lawn doesn’t mean I ready to go mow a MLB baseball field.

[dannobee]

If someone brought me an unknown alloy (short of analyzing the material), I'd start with looking closely at what the part is and look for any identifying marks, such as the A356 or A319 mark used on various sand or investment castings. In this case you can see that a 964 case is die cast aluminum. There are only a couple of alloys that will reliably work with a die casting. A380 being the most common. If you tried die casting with the common sand or investment casting A356 alloy, you'd likely have unacceptable cracking problems in the manufacturing process.

Since the most common alloy used in this case (pardon the pun) is A380, we'd whip out the chart and find the alloy on the chart. Pick the welding rod with the most advantageous properties for your particular application.

https://www.hobartbrothers.com/downloads/aluminum_selecti_1lOo.pdf

Since we're welding up the case, and not welding on, say, an additional bracket of a different alloy, we'd look across the chart for A380. That leaves us with 2319, 4043, 4943, and 4145. Since the boxes with 4043 and 4943 are empty, neither of those is recommended. (4943 has higher strength than 4043 filler rod, otherwise similar properties).

4145 would be my choice. 2319 would be my second choice. Would 4943 work? Sure, I'm positive that many cases have been welded with that rod. Is it ideal? No. And of course, if there's aerospace or aircraft usage, all bets are off and consult a qualified engineer.

And of course your welder should know about preheating and that engine oil permeates aluminum and will need a higher AC balance to suss out all of the impurities. And if the welded area is in a critical area or pretty big, or not clamped down properly, the case might need remachining to bring it back to "square to the world."

[Jeff Higgins]

Where is it damaged? What is the nature of the damage?

I'm only asking because sometimes we can repair minor damage on these cases (and other cast engine components like chain boxes, cam towers, etc) without having to resort to welding. Anything bearing any sort of a load, or seeing oil pressure or anything like that is obviously out, but not everywhere on these cases fits that description.

[drola]

Thanks for all the feedback. I should have been more specific when I started the thread.
This is a 964 engine that was in an accident and the header snapped off a chunk of the threads where the oil supply line threads into the case. Fortunately it was a clean break and I don't see any distortion so it mates up very nicely. Seems to me like a pretty straightforward repair, but don't want to take chances using the wrong TIG rods. The threaded pipe still threads in smoothly when I mate the broken piece up to the case and the threads all still line up nicely and the pipe turns without resistance.
So I was told to clean it, clean it again, and then again. Grind out a little bit of material all along the outside edge of the break to create a "v" so the TIG has something to bite to, and clean it again.
But the welder asked me to find out what that case is made of to determine what type of rod to use.

[john walker's workshop]

Be interesting to see the fix on that difficult job.

[Jeff Higgins]

Yeah, rats - that's certainly a "must weld" kind of a repair. Fortunately, while it is an oil line, there is no oil pressure. It's gravity feed from the tank to that connection. Still nothing on which we would ever want to take chances, though. I was hoping you would luck out and be able to avoid welding.

I once had part of the top ring land blow off of the #1 piston, and then the CE ring and surrounding area failed. Cylinder and head were write-offs, eroding a pretty good groove between the two. It also managed to blow a pretty good hole through the front of the left chain box. I managed to repair that by countersinking both sides of the hole to create an hourglass kind of a shape, then filled both sides with JB Weld. With no oil pressure, no real stresses, and nothing but crankcase pressure, it's held for darn near 20 years. I was hoping maybe you were going to be similarly lucky, but that just isn't the case (please pardon my terrible pun...).

The good news is that being such a small repair, concerns over expansion/contraction, pre-heating the surrounding area, the "wrong" rod, and all of that are really almost moot. Kudos to your welder for asking all of the right questions and being very careful but, in the end, I think many of his concerns will prove to be immaterial (another really bad pun, but I can't help myself).

The post welding cleanup is going to be the hardest part of all of this.

[Magyar Kiwi]

Hi
There may be an alternative repair for this damage:
Machine the internal threads further into the case.
Machine the surface of the case to make a new flat counterbored surface.
Fabricate a new longer steel union which screws into the deeper threaded bore in the case and seals on the new flat surface.
Cheers

[drola]

Well, here is the outcome. Welded up pretty nice. He added lots of material which is fine with me. I filed the mating surface flat so the crush washer will do its thing. I plan on getting some jb weld or marine tex and filling the cracks on the inside of the threads, then putting more of it on the threads of the oil line that screws in there, give a good snug, and never touch it again. Fortunately, the oil line has its own nut and I can tighten it without needing to do anything more than holding this one in place.
I hope it works. It'll probably be about a month before I get this motor in my car so until then I'll just have to wait....

[mb911]

Ugh this is not a quality repair just so you know. Big dollars at risk. For reference this is what aluminum though not cast should look like

[Evan Fullerton]

Cast oil impregnated aluminum is never going to weld like that.

[mb911]

Originally Posted by Evan Fullerton

Cast oil impregnated aluminum is never going to weld like that.

Ok I will bite. How many castings have you welded? I have welded 1000s of castings including hundreds of fan and fan housings for our 911 engines. I don’t disagree that it won’t look like my welds on the .090 5052 h32 but it would look way better and actually look like a bead. It’s literally my profession unlike most whom just buy welders and all the sudden are “welders” not saying that is you Mr Fullerton just saying that it is something I deal with on a daily basis. Today I was doing d1.1 unlimited thickness testing for part of the day and then doing a magnesium fan housing this afternoon.

[nocarrier]

I'm with mb911 on this one. Before that welder was worrying about the composition of the case he probably should have spent some time learning the basics. Like properly cleaning the aluminum before even attempting this repair. Those welds look like the have absolutley no penetration and the craters on the tops of the welds shows he's lacking puddle control (and adding a small dip of filler) when coming to a stop while welding aluminum. I can also see where it looks like he either dipped his tungston or had it too far away from the workpiece and didn't even take the time to clean the soot off of the weld area.

I also think it was a really bad idea to re-use a cracked threaded boss. The minute you try and torque that I have a feeling it's going to crack right off. I would have machined a new threaded bung with a chamfer incorporated into it for a place for the weld bead to lay into. I'd wrap my bead around the new boss and up and over that boss that the bolt is threaded into. I'd then file/machine the boss back down and re-machine the flat surface of the bung blending the weld.

This repair is a disaster.

[Evan Fullerton]

I’m not saying it is not an ugly repair and I’m no professional welder, only an engineer….. but your here’s my beautiful stack of dimes picture on virgin plate is an unreasonable expectation for the OP.

Penetration does look lacking, weld prep doesn’t look like it was great but enough JB weld and it probably will work.

Just potentially an expensive problem when/if it fails again.

But the motor has already been running when it failed the first time so maybe it’s worth the roll of the dice.

[john walker's workshop]

Mmmmm, JB. Ya sure.

[Evan Fullerton]

Ever order something that shipped FedEx air freight? Good chance it flew on a 737 with aluminum honeycomb flooring I worked on held together with guess what……. Epoxy.

Would the best option be to dis assemble the engine, mill off the damaged area, machine up a new boss, and have a great welder weld that on……. Yes.

In other cases where it just has to work, a structural adhesive repair can work to reinforce and pin hole seal a questionable weld.

[mb911]

Originally Posted by Evan Fullerton

I’m not saying it is not an ugly repair and I’m no professional welder, only an engineer….. but your here’s my beautiful stack of dimes picture on virgin plate is an unreasonable expectation for the OP.

Penetration does look lacking, weld prep doesn’t look like it was great but enough JB weld and it probably will work.

Just potentially an expensive problem when/if it fails again.

But the motor has already been running when it failed the first time so maybe it’s worth the roll of the dice.

It really depends on who is doing the work and their experience. Speaking as a former professional aerospace welder (haven’t done that in 20 years) when doing repair work which is outlined by FAA and also the AWS and API etc this would never be an acceptable repair.

Here is how I look at it from my perspective. I am assembling an engine that is easily worth 35k. The area that controls oil bypass and pressure is compromised and poorly repaired with darn near looks like the as seen on TV alumiloy and now you are going to try and enjoy the car which is why we have these cars? Man one piece of road debris or anything for that matter could bring that joy to an abrupt ending. Not worth the gamble

[mepstein]

I’m pretty lucky that I met Ben /Mb911 years ago and he’s been willing to do so many welding repairs and other projects for me. There’s very few people with tens of thousands of hours experience at their profession.