Need HELP Broken off piece of case-weld?

[mazing3]

Hi Guys,

I have a heartbreaking problem that I really need some advice with. I'll start with the actual issue that I need opinions on and then get into the back story...

When attaching my newly rebuilt 915 to my newly rebuilt engine I heard a loud pop and it took me a few minutes to figure out what had happened. Turns out I broke a chunk of the front of the case off as you can see in the picture. I looked at everything again today and determined the problem was 3 of 4 pretty bent transmission mounting studs. Couldn't really tell until I removed them all on a hunch. I need to know what you guys think my options are here. It is a clean break with no shatters or other collateral damage. Nothing that seems to interfere with the mating of the case halves or #3 P&C and just one small hole beneath the breather that has any access into the inside of the engine. Nothing fell in as that part is part of the chunk that came off.

Can this be welded back together or re-attached in any other way? Is there any risk of lateral thermal spread from that on my case parting seal there in the middle? I have a machine shop here in Atlanta that I've worked with a lot in the past and trust but want to know some options before I talk to them. I would SERIOUSLY like to avoid having to totally tear this whole thing down again and start over if that is at all avoidable. Please let me know what you think.

The back story is that I have been working on this for about 3 months. Lost a rod bearing on my previous motor, bought another one for parts, and started all over. Even turned my 3.0 into a 3.2ss. Redid my wiring harness, reconstructed my fan shroud, got everything powder coated and just when it looked like it was time to install I decided to rebuild my 915 to see what that was like. I had gotten one with the motor I bought. It is a 915/68 so I figured I'd just make a great box out of the best parts of the 2 I had. So I did. So last night I finished the trans and was very proud and happy and excited to get to spend today installing it all and hearing her come back to life. So when I heard that POP last night I just sat there stunned and contemplated kicking the car off of the jack stands. I opted to drown my sorrows in copious amounts of Chimay instead. So hopefully there is an easy answer to getting this thing sorted that doesn't involve me starting all over again.

Thanks!

[mattC2993]

I would say it could be weld repaired but you would have to find a competent welder who has welded on aluminum Porsche cases before. It would require disassembly. My guess is that the preheat for welding is around 400F. After welding it would have to be checked for flatness and at least some machining is going to be required. Getting another case might not be any more expensive.

[steely]

dude, so sorry - you will get thru this.

[juanbenae]

man, I bleed for you. could this competent welder matt reference tack, or spot weld the piece at various locations from both sides a little at a time to not cause terminal heat damage to the new internal motor parts? matt references that the material, the block & chunk need to be heated prior to welding, so maybe im waaayyy off base?? one good thing is that the piece is so large you have plenty of surface area to fortify. the tranny bell housing mates right up to it, so consider the support it will provide when all back together and fastened properly. maybe, dare I say jb weld, or other more elegant epoxy around the perimeter of the compromised to internal case location.

how will this motor be driven? just seems you did all this work, the motor & gearbox, n you said YOU... so you really are informed enough to know the right thing to do... good luck with whatever you do. hugs.

[Dan J]

Hate to say it but a new used case is the best answer

[Ronnie's.930]

[mazing3]

thanks everyone and thanks for the sentiments too. I have to admit, the first thing that flew through my head was JB weld too. I've seen it do some amazing things and the surfaces are perfect to set it up and clamp it. It's just the thought of it that concerns me. I like the idea of the spot welding in a few strategic spots. All this is going to be part of the conversation with the machine shop tomorrow so thank you again for the ideas. The lucky thing is that at least this is the left half of the case so the holes on the right are still good so I can get it back in my engine stand. Man, I am seriously looking for some silver linings here aren't I.

To answer the last question...The car is a street car primarily but it isn't all that stock. Was seeing 224 at the wheels a few weeks before the bottom end croaked and it's probably a little more stout now after adding the new 3.2 Ps&Cs.

[mazing3]

lol. just saw Ronnie's JB Weld. good stuff. Truthfully, If I can figure out a way to better reinforce that one stud that goes through the broken chunk I may actually consider it! And there is a spot that could make this possible...

that vacant threaded hole you see is part of the original CIS throttle rod plate which I don't use with my PMOs. Might be able to fabricate something using that hole as a base. Hmmmm.... this may be a bad idea or it just might work... probably a bad idea. maybe.

[Ronnie's.930]

I don't think the JB weld, no mater how you put it on, would hold past the first time you released the clutch (or maybe the first throttle blip in neutral). I'm glad you didn't take offence to my little "JB Weld" joke. There is another guy on here, "quatrorunner", that once posted a picture of JB that he had slathered all over the case of his engine when installing one of those "leak fix collors", and I have been yanking his chain about it for a year now. I thought of him when I saw the picture of your problem.

[mazing3]

ha ha... no problem. I've actually seen first hand that stuff defy physics in some crazy ways so no telling how good it would work. Just not so sure that is enough to make me actually try it here though.
I'm leaning towards just tearing it all down. Everything is already spotless, the hardware is brand new, lots of case and gasket sealant to deal with but that's not so bad. Probably take a fraction of the time to rebuild. Almost like a big lego set where all the parts are ready to go. I'm getting too good at this now though

The kicker is that I had a good case on my old motor and sold it here on PP.

[ionaetp]

I thought of him when I saw the picture of your problem.

[Porboynz]

I watched an alloy 915 case being welded after a diff detonation and the guy preheated the alloy with a blow torch before welding, it was full on dante's inferno so repairing your engine case is going to need a complete tear down. That makes new cases look like an easier long term solution. Commiserations, I guess if it don't fit don't force it huh? I usually risk my back by mating gearbox to engine by hand, both on the floor, straddling the gearbox and sliding it into position.

[Justin@Athens]

I died a little on the inside when I saw the photo. I can imagine myself under the car and holding the piece in my hand and immediately thinking--jb weld? super glue? What do I have in the cabinet to fix this--ultimately I think a new case is in order. But you might try to fix it with an "off the shelf" fix and just see what happens. I am having difficulty imagining a whole lot of torsional force at this specific location, but the heat would probably stress the repair more than anything.

[mazing3]

Thanks Justin and Porboy. Good insights. This thing is coming apart yet again one way or another. This would be the 3rd tear down I've done since April. My motor after the rod bearing went, then the donor parts motor at the same time, and now the one I just got done building. I'm getting really good at this. I wish I wasn't getting really good at this.

[tobluforu]

Wow! JB weld is amazing stuff, but the tranny being bolted up the way it is, I really doubt it will hold up, but I guess it's worth a shot. I cracked off the bottom part of the tranny where the clutch cable threads through, used JB along with gator epoxy and it's still going strong, but that's a whole different area.
Man do I feel for you, good luck

[john walker's workshop]

you guys crack me up with all the glue/epoxy advice. glue, really?

[ClickClickBoom]

Been welding for 35 years, aluminum moves like crazy when welding, the expansion and contraction on that type of repair would be crazy. If it was a 150K motor and you wanted to take a chance you could stitch/tack the whole crack. I would give it about a 10% chance of success, only because the case is so clean. The warping is another issue, and since its a fresh rebuild assembly, I would get a new case and start fresh and proper.
Sorry for your trials and tribulations.

[schumicat]

that sucks but keep things in perspective, this is nothing compared to a experiencing a serious illness or injury. maybe get a cheapo $2500 2.7 or 3.0 complete motor to use in the meantime and sell it when the rebuild is done (could probably get all your money back less shipping). I'm still not clear how bent studs would cause this to break. like the other post says I push the engine and trans together by hand and I doubt I'm strong enough to break that piece off. If JB Weld held you should do a testimonial for them.

[Charles Freeborn]

What Click Boom sez. You'd have do tear it down to the bare case, weld and re-machine - line bore, etc. Better off finding an new case and building it back up from there.
Good news is that with the experience already gained you'll have it down and back in half the time it took on the first go-round.
-C

[HawgRyder]

This probably is a good reason for assembling the case and trans before they are installed.
It gives you a 360 deg look at the mating flange so that this type of damage is reduced.
I also agree...new case...peace of mind for the life of the car.
Bob