handling contamination on an aluminum engine block repair

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Hi all,I took on a field project yesterday piecing a broken plate off of a BMW engine block.  It is the part that bolts onto the transmission right where the starter mounts.  Behind the plate is an oil galley with two plugs which also were victims of he breakage.The mechanic that was installing the tranny failed to notice that a locator pin was not in its place and attempted to tighten down the bolts holding the parts together and snapped it off.  I told the mechanic to make sure the area was totally, I mean totally clean of any oil and to wire brush it down to shiny metal which he did.The tricky part was to make sure the oil galley way was sealed up so that oil did not drip out after the repair.  I beveled the broken plate for penetration, made up a plate that bolted to the existing hoes on the engine block to hold the part in line, on the same plane and tacked it up.  After making sure everything was inline, I heated it and started welding it up front and back in steps so that when I removed the alignment plate it would not pull one way or the other.The engine was on a bench so I could rotate it as needed for better position and everything was going along fine until I asked them to rotate the engine so I could get at the final segment in a close to flat position.It turned out that they had left the oil in the engine and when they moved it, the oil flowed right out of the crack and into the final beveled section!!!!  After raising it with some blocks so the oil flowed back towards the front of the engine I wiped it down with gasoline, put a torch to the area to burn out the oil and repeated this several times.  I wire brushed the sh-t out of it and started welding again.As I expected from that point on I could not close the holes that resulted from the contamination.  I spent an extra hour on it, welding brushing, welding, brushing, grinding down, welding, brushing with poor results as the area refused to seal.From experience I learned that eventually, the oil will burn out and that I will be able to seal it up but we might be looking at hours of repeating this cycle over and over again until it finally all clears out.  The best I was able to do was build up an area and put a "cap" over the porosity created but in doing so the area was higher than the plane it needs to be on and had to grind it down which exposed the porosity again.This is an issue because it is right where the oil galley is broken so oil will leak out unless I can close this area up.Question:Does anyone have a system for cleaning the oil contamination out or am I doomed to have to go at it for hours more on it? While the client is paying for my time I also don't want to bleed him on this project even if it was not my fault technically as I told them to make sure there was no oil, dirt, grease, etc. present near the area to be welded as it would cause exactly what is now happening.Using hind sight, I should have sealed off the oil galley ways prior to fitting the piece on as this would have taken care of the oil seepage right off the bat.  Oh well...I am thinking of gouging out the area  behind the oil plug and sealing it all up, then the issue of oil leakage is taken care of, I think the repair will be fine with the porosity that I'm fighting now.Pictures of the break attached.  I don't have any of the repair but will take some when done.Anyone of any thoughts on the best way to proceed????  I will be going out there again in a few hours to finish it up.Thanks,Tony Attached ImagesLast edited by therrera; 03-30-2013 at 12:53 PM.Reason: for clarity and to add one more picture
Reply:Unfortunately I do not have advice that is different than you already know.  I do wonder if gasoline is a good or bad cleaner though.I do have a question - does that engine belong to the mechanic?  If it's a tranny job for a customer, does the customer know the block is being welded?I'm sure everything is squared away - just thinking as a customer I'd be requesting a replacement block, not a weld repair.  If it's my own motor - I might weld itDave J.Last edited by MinnesotaDave; 03-30-2013 at 12:53 PM.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Have to grind all the weld around the journal out, clean it again even way back into the journal both ways, and start welding again. Once you get the contamination into the metal it has to be taken out.If I had to do the job I would have welded up the oil journal section separately, notched the broken piece around the journal section and then welded on the broken part.
Reply:I would be pissed if I was the customer of this engine. There is no way short of disassembly, cleaning, major gouging, welding and re-machining you can repair that block to any level of strength. I have done block repairs on blocks and heads and with this going into an oil galley a failure could result in very bad things including death and burning of the driver. Walk away.Syncrowave 350Coolmate 3Millermatic 251Spoolmatic 30A
Reply:When doing engine castings I always weld it twice.  The first pass brings all of the oil out of the aluminum and into the weld then you grind the first weld out and weld everything again a second time.  The second weld will come out beautiful.
Reply:Leaving all the rest of the problems already mentioned aside-The perpendicularity of the flange face (which is the starter flange face mounting)has everything to do with the engagement of the starter pinion gear to the ring gear.If this busted flange is warped (very likely), or not dead nuts parallel to ring gearand square to block back face, this will be noticed when the starter engages the ring gear......and that's a biggie. Sometimes the jobs that help your bottom line are the ones not taken.Last edited by dave powelson; 03-31-2013 at 02:13 PM.Reason: correctionBlackbird
Reply:Welcome to the wonderful world of "I Don't Think So"....You may have just bitten off more than you can chew.I would not touch that job because after you do you are it....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Cleaning with gasoline wasn't much better than the oil you were trying to clean up.  Gasoline is a petroleum product, duh. Denatured alcohol works fairly well.
Reply:If that is a commercial shop, the customer gets a new block.   If you are doing that for a friend I would still be scared that even if you welded it perfectly, the last tightening of all the bolts would crack something, wasting all the time.  I assume it is Iron?
Reply:Originally Posted by blackbartIf that is a commercial shop, the customer gets a new block.   If you are doing that for a friend I would still be scared that even if you welded it perfectly, the last tightening of all the bolts would crack something, wasting all the time.  I assume it is Iron?
Reply:Sorry about that.  On aluminum I would do it, everytime the puddle gets contaminated, stop clean and keep going, If it's a block for a friend.  I have welded extremely contaminated aluminum that way, sometimes only 1/2" at a time. It seems like eventualy all the contaminents come out.  I hate it when people don't read posts, especially the title!
Reply:Answer:  Mechanic buys a 'new' block.btw, gasoline is NOT a 'cleaner'.Acetone is a 'good' general-purpose cleaner-degreaser for use before welding.As to you welding the alumium block and getting oil in the weld area, you'll have to grind out all the 'dirty' weld attempts.  Then drain the block completely of oil, then clean the areas to be welded with acetone and then grind (carbide burrs) and/or use stainless steel wire brushes to remove the aluminum oxide 'skin' from the aluminum.  And then clean with acetone again.  Make sure there is no oil anywhere in the area being welded (even after you tilt/tip the block around).  After all that cleaning and prep is done, then you could consider trying to start some welding.And you'll probably still end up having to grind out the first (several) weld attempts because they got some oil residue into them and buggered up the weld.And you really can't heat up an aluminum block hot enough to burn out the oil in the crevices and 'pores' of the aluminum.  Getting it that hot and you either destroy the aging/heat-treatment of the block itself or melt the block.And after all that welding, if you somehow actually did get the multiple cracks all welded up, the flange would still have to be machined.Answer:  Mechanic buys a block (new or reman).  The best laid schemes ... Gang oft agley ...
Reply:Hello fellas (and lurking ladies),The job is done.  I proposed to the shop owner to grind out the whole area where the contamination set in due to the oil splashing the area.  He had it ready for me when I showed up on Saturday and located the source of the contamination which was a hole that had not closed up and some porosity also.   He had gouged out the whole area under the oil plug seen in the photo.  He used carb cleaner and a torch in repeated cycles to clean it off well and then wire brushed it. When I showed up, I wired brushed it again, heated it and started welding it.  The puddle flowed like butter.  I finished sealing it up in about 1/2 hour.  Then he closed off all the oil ports and manifold openings and pressurized the the oil journal and we used soapy water to see if there were any leaks.  We used that method earlier to detect some leaks before deciding to gouge it out.So far so good.  The car (and engine) is the shop owner's.  I forgot to bring my camera so he took some shots for me and will send them to me shortly.  I will post them.As mentioned by VPT, when faced with a repair such as this one again, I will close the oil journal first as well and THEN weld out the rest of it.  This way I would have clear access to sealing it first and most critical.  The rest of it was a standard bevel and weld type of repair.  Also instead of fighting the contamination and boiling it out over a long drawn out process of clean, weld, clean, grind, weld, etc.  I will opt to just cut it out as suggested and start over.  My bad.....Thanks for your advice and help,TonyPS: he told me that they checked the mating surfaces with feeler gauges and everything was good.Last edited by therrera; 04-01-2013 at 02:45 PM.Reason: For more detail...
Reply:Glad you got it worked out! Did you get any pics of the finished job? I was thinking of the trans surface later on after posting. Normally I would bolt up and use the trans (spare bell housing) for locating the broken part while welding and holding it flush with the rest of the mating surface.