Case repairs

[sicivicdude]

There have been a lot of questions lately about case repairs.

This is a typical "break" inside a blaster engine. Engine arrived complaining of a high idle (unmetered air entering the engine through the break).

Pictures start after the engine was disassembled and generally cleaned:

The hairline crack inside, left side case

But you can see, the entire case was "shifted" and wouldn't have sealed:

The only outward sign of damage:

The break you saw, from the inside:

Your left case half welded:

Your right case half welded:

At this point, we've only got the metal melted back together. It's not even CLOSE to ready to run, we've got a ways to go still to get there. Don't worry one bit about the appearance. Generally the welding process on cast leaves a lot of tiny bubbles and "blobbed" areas. The trick is to get enough material built up on the weld to have it there to cut back down to the proper size.

 

[sicivicdude]

After all of the "hot work", we move onto finishing processes.

First a carbide burr and die grinder to get the case back to shape and then a sanding drum to finish off the inside.

The mating surface becomes a concern then. Welding left it much higher than the area around it.

After milling, the mating surface is only about .001" off and a quick trip to the lapping stone to finish it flat and we have a repaired case, ready to go.

 

[blasterBruce]

Great Work and Great Pics James !

too bad you just ruined every bearing in there, no matter how much cleaning you do

 

[sicivicdude]

After this particular welding and finishing session, I chemically cleaned it using detergent in the parts washer, baked the cases to remove all of the bearings and relubed them, and then media blasted the cases to get off all of the "crud".

I think I'm going to reverse my process from now on though. I think it will be chemical cleaning to remove any large particles and then baking to remove the bearings (just to keep down contamination), welding and finishing, and then media blasting.

This will ultimately expose the bearings to a lot less foreign material needing a lot less cleaning and lubrication before they're runable again.

I'll snap a pic tonight of the cases all reassembled.

 

[blasterBruce]

Makes sense on Cleaning them and Removing bearings first , That way your Dealing with a Clean Ready to go Part Before you Flip the Switch on the Welder !

 

[sicivicdude]

Makes sense on Cleaning them and Removing bearings first , That way your Dealing with a Clean Ready to go Part Before you Flip the Switch on the Welder !

Exactly!

I don't turn any of the bearings anywhere in there while I'm working so all they need is a good strong flushing before they can be used (transmission bearings we're talking here, crank bearings were replaced!) but it'll be even better to not even have them in there from now on.

 

[slickerthanyou]

Looks good James! It would take me a few tries before I could get that done with the mig!

 

[sicivicdude]

Looks good James! It would take me a few tries before I could get that done with the mig!

Next one I get with a huge hole in it, I may be "lining" it with the tiggy (just to get a good single layer of clean material to start with) and shipping it to the 'burgh to see how a spool gun will do on filling in .

 

[slickerthanyou]

Next one I get with a huge hole in it, I may be "lining" it with the tiggy (just to get a good single layer of clean material to start with) and shipping it to the 'burgh to see how a spool gun will do on filling in .

I'd try it! I always run straight argon for everything, a little more expensive but nicer welds all around!

 

[sicivicdude]

I'm curious for my own sake. I don't know how well the spool gun does on that first layer of aluminum, I usually have to hold heat on the cast and allow the EP to flow out over the metal and break up oxides and other crud and the miggy doesn't have that option but once there's a layer of good aluminum to bond to on there, I bet it would fill in great.

 

[Blaaster]

I have found with my dealings with Aluminium that the MIG seems to like the parent metal spotless, cast is very hard to get perfectly clean and oxide free due to the nature of the cast structure.

One can get the TIG to float the imperfections up to the surface but you dont have that chance with the MIG.

Once you get a build up with the TIG it should be eaiser to pile on more metal with the MIG.

The guys at the technical college when sitting practical exams would clean the previous weld with a brass wire brush directly before they would lay down the next pass. It helped keep the oxidation to a minium.

 

[sicivicdude]

That's my understanding of it. I think it would work well to weld up a large area if I did the first layer of the weld with the tig welder to get a single layer of clean filler and then laid the mig welder down on top of that. For some large holes, the tig is a slow process.

 

[slickerthanyou]

I'm curious for my own sake. I don't know how well the spool gun does on that first layer of aluminum, I usually have to hold heat on the cast and allow the EP to flow out over the metal and break up oxides and other crud and the miggy doesn't have that option but once there's a layer of good aluminum to bond to on there, I bet it would fill in great.

Brass brush on a varible speed drill cleans almost all that crap off to bare aluminum. Make the start alot easier.

 

[slickerthanyou]

I have found with my dealings with Aluminium that the MIG seems to like the parent metal spotless, cast is very hard to get perfectly clean and oxide free due to the nature of the cast structure.

One can get the TIG to float the imperfections up to the surface but you dont have that chance with the MIG.

Once you get a build up with the TIG it should be eaiser to pile on more metal with the MIG.

The guys at the technical college when sitting practical exams would clean the previous weld with a brass wire brush directly before they would lay down the next pass. It helped keep the oxidation to a minium.

Guess i didn't read far enough!