Supercharger Casting Repair

[Don52]

An friend and associate just purchased a used supercharger for his 15 year old Mustang, which he keeps in the garage and drives for special occasions. The super charger itself was in good shape, but when the previous owners engine failed something must have hit the drain plug boss on the bottom casting of the supercharger and cracked it. The first three pictures show the dent in the casting and some of the cracks that were present.






New castings are no longer available from Ford, so he asked me to weld it up. The first question is what Aluminum alloy was the casting made of. The casting was very smooth and there were what I believe might be ejector pin locators, which would indicate that it was die cast. Usually the ejector pins are 1/8 or 1/4 inch, but these were larger so I wasn't sure.

4. Ejector Pins ?


The most common alloy for die cast Aluminum is 380. To confirm the alloy my friend brought it to a metal scrap yard and had them shoot it with their X-ray gun. The concentration of the various elements matched the Aluminum 380 alloy, so I purchased one pound of 2319 welding wire, which is recommended for welding this alloy.

I decided to machine off the existing boss because the crack around it would be difficult to grind out and the threads in the boss were stripped as shown below anyway. What was left of the threads were also filled with RTV.

5. Stripped threads on drain plug boss

[Don52]

Because drain plug boss was cracked on three sides and only supported on one side, I decided to cut it with a hole saw, because I was concerned that a more aggressive means (Such as a large end mill) might damage the casting if the tool caught and ripped off the boss.

6. Setup to hole saw off the boss.


7. Hole sawing off the boss



Now that most of the material was removed, I could use a boring bar to remove the rest of the material and open the hole up to a standard size.

8. Boring the hole to size.


Next I made a replacement boss for the drain plug. My friend didn't want to add the threads at this time because it is primarily required for the PCV valve that he didn't want to add just yet.

9. Turning and parting off the new boss


10. Grinding a drain passage in the top of the drain boss

[Don52]

Next I went over the cracks with the TIG torch to bubble the impurities to the surface. It also showed up the crack as a black line.

11. TIG heating the cracks to bubble up the impurities



Now that the cracks were visible I ground them out from the inside of the casting.

12. Grinding out the cracks from the inside of the casting.



To keep the casting from cracking we preheated it before welding to 250 degrees F.

13. Preheating the casting



Next I welded up the cracks from the insides. In some cases I had to grind out the weld and re-weld it because there was still too much porosity in the weld. below is a picture showing the welds on the inside of the casting. It was difficult to weld because the casting was hot and the walls got in the way of the torch and filler rod. Below are the welds on the inside of the casting.

14. Welds on inside of casting

[Don52]

Then I ground out the cracks from the outside of the casting and welded it up.

15. Welding the outside of the casting



16. Welds on outside of casting

[aametalmaster]

Nice work as always buddy...Bob

[Ltbadd]

Good work Don, very thorough

[Oldgrandad]

Nice Job, Great photo's. The step by step is wonderful, shows those just breaking into the biz the RIGHT way to do things. Short cuts don't cut it. #13 stating you had to grind out welds and redo them, happens a lot with auto repairs. Just another detail not often mentioned (like it doesn't happen ).

[Don52]

I appreciate all of your comments.

-Don

[tarry99]

I use acid for cleaning prior to welding aluminum......especially when it's been around oil and grease.

[FusionKing]

I use acid for cleaning prior to welding aluminum......especially when it's been around oil and grease.

We do quite often as well. Makes it look brand spankin' new

[Ltbadd]

I use acid for cleaning prior to welding aluminum......especially when it's been around oil and grease.

Can you provide a link, or brand name of this product?

Thanks

[tarry99]

Sorry.....been away............get yourself some disposable gloves.....and eye protection......and a few of those little acid brushes plumbers use for applying flux to copper before they solder it.......a little goes along way........might need a second coat if it's real dirty...........Home Depot sells some........body shop supplies or a good welding shop should have it.............Good Luck!

[Ltbadd]

Thanks!

[FusionKing]

We use aluma-clean and aluma-brite by the gallon.
Truckers use it to clean trucks. Part stores carry it for around $15 a gallon. I sometimes buy it by the case and use it full strength with a spray bottle.

[Ltbadd]

We use aluma-clean and aluma-brite by the gallon.
Truckers use it to clean trucks. Part stores carry it for around $15 a gallon. I sometimes buy it by the case and use it full strength with a spray bottle.

Ok thanks, I remember this stuff, used it many moons ago...