Engine case welding..

[Enginefreak~66]

Hey all,
Need to get a vw engine case welded, Have found a guy that will do it for me and he just needs to know the percentage of magnesium in the case so he can order the welding rods....
It is a single relief 1500 type 3 case..
Just need to know the magnesium percentage of the case....
Cheers,
Lawson

[Marc]

I don't know the exact Mg percentage but it's MOSTLY magnesium (if it ignites, good luck extinguishing the fire). Later cases had either AS41 or AS21 alloy (Magnesium w/4% aluminum, 1% silicon or 2%/1% respectively).

If your case is US-market of 1968/1969 vintage I wouldn't waste the effort - those years were cast to be less dense in the hope of improving heat transfer through the case and the result is increased incidence of pulled head (and other) studs, cracking, and warping compared to earlier or later cases. They're too light for boat anchors and awkward as doorstops, but those are still both better uses for them than trying to build a decent engine.

[Enginefreak~66]

Are they the same percentage as the as41 cases? Because I read somewhere that 41 and 21 give the percentage of the magnesium?
Thanks again..

[Marc]

That'd be mathematically impossible, if the AS41 has 2% more Al than the AS21, the Mg percentage could only be lessened.

Again, if your case is `68/`69 don't waste your time on it. If it's pre'68 I suppose it's not completely pointless to try to salvage it, but all you'll have in the end is a small-passage case that's not suitable for much more than a bone-stock SP build.

I'd instead be looking for a decent "ribbed" AS41 case. The angled panel below the pedestal mounting point has horizontal "washboard" ribs in its surface like this one (of course if it's for a Type III application it'll need the provision for the oil filler/dipstick tube at the RR corner of the sump). http://www.popsci.com/sites/popsci.com/ ... k=xKLSsIj0

[Bruce2]

AS41:
Aluminum 4%
Silicon 1%
Magnesium ~95%

AS21:
Aluminum 2%
Silicon 1%
Magnesium ~97%

If your engine case needs welding, throw it away and get another. Welding won't work. It will just crack again where you weld.
If you absolutely have to have a numbers matching engine in your car, get another car.

[Ol'fogasaurus]

(stating the obvious for those who don't know) If you are going to weld a crack then the usually thing is to drill the ends of the crack to stop later travel.

[Enginefreak~66]

Thanks heaps for the info,
So are the single relief cases the same content as a as41? I don't have a cracked case, just modifying the standard one
Cheers

[Piledriver]

Welding behind #3 for a big bore/to prevent cracking?
I still wouldn't bother with an early case.

[Enginefreak~66]

Nup, modifying for a different oil system, dry sump etc....bit of a project engine. Don't really have the $$ for a new case, and have already put a lot of work into this engine case...
Cheers

[Piledriver]

Enlarging the oil passages? Feeding back in at the cooler ports?
IIRC the earlier cases were ~AS21-ish, but if its a cheesecase you are better off starting over.

[Enginefreak~66]

Yep doing both those.....
Only a 1600 but with 9:4:1 compression, injection ect.. more valves... going to be pretty wild.... will post more on it when i start assembling...
Cheers,
Lawson

[Marc]

IMO the sunken stud mod on #3 top-front does as much to limit cracking as welding or plating the front of the case - and doesn't warp the hell out of it.

[Enginefreak~66]

Ok thanks heaps, Wondering if the engine case will be warped much? If so would heating to 250/300 degrees Celsius help?
Cheers

[Marc]

If you're just welding full-flow bungs to the oil gallery I don't think there should be significant distortion at the case & cam tunnels or the parting line - seems to me it'd still be best to do with the halves torqued together, though. The fellow who does my TIG welding these days preheats items in an oven and uses a rosebud on an oxy-acetylene torch to keep them warm while he's working, then back to the oven for a gradual cooldown. Still no guarantee against distortion, but he must think it's worth the trouble. Scary part is hitting Mg with a torch (it'll ignite at ~850°C or so).

As for filling in the area at the front of #3, I've never seen one that wasn't affected badly enough that it needed align-boring afterwards....but welding in a plate rather than filling the whole void with weld causes less distortion.

I had a case once that had a hole over #3 where the rod had tried to escape; otherwise there was very little damage so I had it welded up. The welder I took it to then chose to do it without the halves bolted together and it warped about .005" at the parting line. It also always "weeped" a little in the welded area, had to slather epoxy over it to get it stay dry. In retrospect, considering how small the hole was, I probably would've been better off just gluing/riveting a patch over it cold