Welding up a hole in a Briggs aluminum block

[creia]

Do any of you have experience welding up a hole in an aluminum block? Even if you did not do it yourself, have you ever taken one to a professional welder? Can it be done successfully? What type of welding- MIG? TIG?
I recently picked up a nice 1971 Briggs 4HP Model 100202 for fairly cheap, and it was even a running engine. Upon disassembly and inspection I discovered that the block had a hole that had been filled with some sort of sealant. It was not hard like JB Weld, it was kind of rubbery. (Maybe "Seal All'?) I media lasted the old paint off the exterior of the block and then removed the sealant. The hole is irregular in shape, approx. 1/4" wide by 5/8" long, on the front lower section of the block and about 1/2" away from where the sidecover bolts up, and about 1/2" above the bottom of the sump.

Other than this hole (by the way it did NOT leak at all), the engine is in excellent shape. All the tins are nice, and all the internals (bore, crank, rod, valve guides, piston/ring gap etc.) are all well within specs. Even most of the bore cross hatching is still somewhat visible These old 4Hp blocks are very hard to come by, unlike it's bigger brother, the Briggs 5HBP 130202. In hindsight, I wonder if I should have left well enough alone on the prior patch and not removed it, as it did not leak - yet? I just have a hard time thinking that a sealant patch is a "legitimate" permanent repair- or is it?
I have not a clue what caused the hole. I welcome your replies
Thanks in advance,
Michael

[bgsengine]

Do any of you have experience welding up a hole in an aluminum block?

Yes

Even if you did not do it yourself, have you ever taken one to a professional welder?

Took it to a local welding and fabrication shop - I think I may have mentioned it once before - intake port broke where carb manifold mounts to it on an otherwise like-new 5 HP on a troy-bilt pony. I think they used TIG but they were professional enough that the repair was barely detectable. (BTW that machine is still running every spring & summer since - over 15 years now.)

Can it be done successfully?

Yes - as noted in prior reply. I would not attempt it myself even if I had the welder not without a LOT of prior practice and testing of the results.

What type of welding- MIG? TIG?

I suspect it was TIG but MIG can work equally as well I believe.

? I just have a hard time thinking that a sealant patch is a "legitimate" permanent repair- or is it?

Nope. It ain't , but sometimes "if it works, it works" is OK too...

I have not a clue what caused the hole. I welcome your replies
Thanks in advance,
Michael

Probably need pictures to guess at a cause - do the hole look like it was worn/abraded/sliced? or do it look like someone hit it with a hammer? and from which direction? If from inside, I'd say probably a forgotten bolt or some such when a rebuild buttoned it up, but if from outside it could be anything from impact damage, engine came loose, something external hit it, carless prying, all kinds of things I can think of and probably twice as many I have not thought of...

[KE4AVB]

You need Argon/CO2 gas mix for either one as a shielding gas. I believe TIG is probably easier or the two. One type of spot welding is used as aluminum melts so easily once you break the oxidation layer. I believe I heard the term as being laying down dimes.

I am looking to get into this type welding myself later this year once I have a steady income. I will drawing that half of a rocker money for a rocking chair then. And my lord I got health insurance and prescription insurance finally. No more $800 per month blood thinner pills.

[creia]

Epilogue...
I ended up taking it to my local welder that I have been going to for over 15 years. He TIG-welded it after extensive prep. The engine is back together and has about 30 minutes of run time on it. Nothing leaking, nothing cracking- "yet"? He did a beautiful job both inside and out as you cannot really tell a repair was even made. He charged me $ 70.00 which I thought was reasonable.
Sidebar comment: The damage had to be from the EXTERIOR (some sort of impact?), not from any internal failure, as the area surrounding the hole protruded INTO the block.
Many thanks to all who replied to this thread!
Michael