Cleaning cast alloy angine sump, pre TIG repair

Hello I am about to replace the engine in my car, which requires me to shorten the engines sump I have chopped off the required amount and would like to know if anyone
knows of a good safe method of throughly cleaning the alloy prior to it being TIG welded up I know a few others that have cut and shut alloy sumps and when they have had them TIG'd back up the cast has sweated out crud making the repairs a bit sketchy and some have found they have minor leaks..(not ideal)
Some have had to use JB weld or similar epoxy's internally to try and fix the leaks, but I would rather spend a little more time doing prep work to give the TIG welder chap the best possible chance of making it seal first time, and make his life as easy as possible
I did wonder about heating the cast alloy around the areas to be welded to see if it would pre-sweat out the crud, but someone mentioned that there /may/ be an obtainable acid dip suitable?
Thanks in advance
Regards Rob
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Rob, try posting your question over on sci.engr.joining.welding. Martin
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martin<dot here>whybrow<at here>ntlworld<dot here>com



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Rob wrote:

I don't know of one.
The problem is that acid isn't good for removing oily crud, and alkali, which is, is also good at dissolving Aluminium and it's alloys.
Best think I can suggest is methylene chloride, which you may be able to buy as a carbon remover in a very good hardware shop, or for use in a vapour degreaser (use as liquid, not vapour). Nasty stuff though.
disclaimer - I have never tried to remove sump crud, with anything
-- Peter Fairbrother
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Do initial wash in clean paraffin. Get an old pan big enough to take the sump. Give the missus 10 quid and bus fare to go shopping, open all doors and windows and stick on the stove and boil in a strong washing up powder solution.
Before bead blasting was common and affordable we used to prepare all the racing engines this way. Won't hurt alloy, opens the pores and gets rid of the oil, even gets rid of baked on oil unless it's really severe like R40 on a Manx head but it does remove most of that.
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On Sun, 24 Feb 2008 19:17:20 GMT, John Stevenson

And whilst she's still out put it in the dishwasher. Then run the dishwasher empty just to be sure...
Charles
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On Sun, 24 Feb 2008 20:47:36 +0000, Charles Ping

Not a good idea. Don't ask me how I know that but I'll fill you in on some of the details of an incident a few years ago :) Having digested a few postings online by Americans regarding engine degreasing in a dishwasher I thought I would give it a go, what could possibly go wrong? Everything, and then it got even worse. Admittedly I had a relatively clean engine but the result was a filthy dishwasher that stunk the whole house with engine oil smells for two terrifying weeks, repeated empty washes just with detergent did nothing other than spread the stink - the only thing that eventually cleaned it was a wipe on wipe off of clean water soluble Jizer on all the manky grey oil stained baskets, half a dozen hot empty washes, and a couple of washes with some very fragrant washing machine fabric conditioner.
It would have been quicker, and significantly easier to go by push bike 30 miles to a friendly engine conditioner, cycle back home and repeat the same exercise a week later when all the bits had been properly degreased.
If it were my personal dishwasher, in my workshop and it were never to see crockery again it probably wouldn't have been a problem - that it was at the future in-laws, in their kitchen that cost 30 grand while me and the future missus were "bed testing the in-laws marital bed" drinking all their booze by inviting all our mates round for a party, emptying their freezer, and abusing their kitchen appliances (see above) all in all made it quite hairy. The final successful dishwasher clean was achieved with a few hours to spare before they returned. The future MIL just commented that the dishwasher looked very clean.
I aged ten years that fortnight, 9 years and 351 days were due to the dishwasher incident :)
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The way I have prepared motorcycle crankcases for TIG welding is to clean them as much as I can with a degreaser and then have them vapour blasted.
Vapour blasting cleans without damaging any surfaces and it cleans into cracks.
I had a crack in a crankcase half which was not visible to the naked eye but leaked oil - that case was vapour blasted and successfully welded by a welder who won't do work on 'unclean' castings as he can't guarantee the result.
By the way Mike, you are meant empty the sump and degrease the castings before they go in the diswasher for the final wash!!!
--
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wrote:

Vapour blasting is only of use on the external surfaces of an engine casting, attempting to clean internal surfaces results in a nice shiny casting ideal for welding.......followed by engine failure as the blasting particles trapped in the casting are released into the oil over the next few days/weeks/months as it goes through a few heat cycles clagging up the oil filter and leading to the bypass opening and hard abrasive particles ripping the crap out of the engine internals.
It's as bad or even worse than bead blasting but the catchy name 'vapour blasting' seems to imply that all that is involved is a vapour of some innocuous or less than innocuous chemical, not a slurry of fine abrasive particles.
At the end of the day you can blame the environmentalists and the politicians for all this mess as you can't escape the fact that the last decent degreasers were banned more than a decade ago.
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Rob wrote:

Ensure SWMBO is out for AT LEAST the cycle time of the dishwasher, preferably longer (so you dont get caught...) clean as much of the oily crud off as you can, then place sump in dishwasher and run most intensive dishwasher cycle. If you get caught I never suggested this ;)
Dave
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use paint stripper and power wash
only use methanol type paint stripper, should say on the label methanol or methylene-dichloride
other paint strippers contain caustic ...that corrodes and turns alloy black
this is my sump after the treatment
http://img.photobucket.com/albums/v190/aboard_epsilon/rover%20420/sumpclean1.jpg
all the best.mark
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Thanks to all suggestions so far
I did use "the tool" (wire brush in drill) to get the outside clean enough to bring it into the house It has been through the dishwasher a couple of times today on the highest setting denoted by pictures of saucepans think the missus was actually a bit surprised to see that I remembered how to operate it! -she had to assist me last time when I put the rocker cover through it :-)
Unfortunately I don't think we have a pan large enough to submerge the sump, as I could possibly get away with it on shopping day (I get a whole day to myself to make a mess, and usually manage to get it cleared up before SWMBO returns) I may be able to fold/MIG weld some steel sheet together to make a makeshift "hot tub", definately an avenue worth investigating
I do have some Nitromorse, and will check the label, but will it get into the pores? as I believe that the problem that it sweats the unweldable stuff out when being welded
Regards Rob
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Can I just clarify for the washing powder solution? Not necessarily after a direct product brand name , but more of a hint as to what you used
Surely not one containing Sodium Carbonate (Na2CO3)AKA cheapo Soda Crystals? as a bit of a search shows it would be bad to use on aluminum
perhaps in this case it would be OK as a weak solution? as leeching out the crud is higher priority than say it "discolouring" bearing in mind its an engine sump and anyone unlucky enough see it close up will have bigger stuff going on
Perhaps a few dishwasher tablets crushed up and dissolved? not sure what they actually contain as the packaging on ours is very vague as to the ingredients
or are we talking about clothes washing powder? (again all the packaging here is suitably vague as to the ingredients)
Regards Rob
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yeah washing powder is quite good
use boiling hot water out of the kettle
and biological automatic washing powder ... use a whole giant box of the stuff .aldi sell good stuff that is half the price of anywhere else.less than 3 ...use.roughly half and half with water .
if you could keep it boiling with a camping stove ....do it .. keep it going for at least 30 Min's
but use the paint stripper first ...the paint stripper will get rid of some things the washing powder wont ....and vice versa
all the best...mark
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Rob wrote:

Hot water, or a dishwasher, will close up the pores - which is probably not what you want.
A last resort might be to strip the oxide layer. 30 minutes in cold 5% hydrochloric acid (aka spirits if salts), then one to three minutes in 3-5% caustic soda at 70 C. Rinse immediately in cold water.
Use an old paintbrush to loosen dirt etc, and take it out if it seems to be dissolving!!
There are better methods, but they are expensive, more complex and use really nasty chemicals.
I don't know about nitromors, it isn't methylene chloride though.
-- Peter Fairbrother
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On Sun, 24 Feb 2008 21:41:05 +0000, Peter Fairbrother

"All Purpose Nitromors" "Contains Dichloromethane and Methanol" according to the tin in my garage.
--
Richard

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Richard Edwards wrote:

Ah yes, I was looking at the msds for
NITROMORS SUPERSTRIP PAINT & VARNISH REMOVER
-- Peter
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