aluminium inlet manifold repair..

[robwizard]

So on Monday I have been tasked with repairing a broken inlet manifold/plenum chamber type thing. It's cast and I have no idea what the grade would be. Basically it wants the holes for the injectors blocking up, which I feel pretty confident with, and also a couple of holes in the side of the main chamber which are a result of accident damage.

I do a reasonable amount of aluminium welding but never done anything like this before.. So far I'm thinking to cut the holes out into nice little squares ready for a repair piece. Clean clean and clean it again.. With degreaser and maybe Heat to try and cook some of the oil and stuff out of it. (Never drone this just read about it somewhere..)

My questions, other than is the above acceptable practice, are in regards to the repair material. I have some aluminium plate, 5mm if memory serves, which I could use. Is it OK to weld the Plate to the cast? It has to be able to withstand 14psi..

Any advise? I'm gonna give it a blast one way or another just want to know what you TIG veterans reckon!

Cheers

 

[dannyp]

clean it and hit it hard with the power, clean it up again and then fill it up.

it's ok to weld the plate to the cast, if it starts been a twerp to weld just go to pure ali filler otherwise id be on a 4000 should hold 14 psi no matter what really

 

[Jim Davey]

Get it as clean as ever you can, inside and out as they are always full of oily gunge on the inside which will cause you nightmares when trying to weld. Not to take a deliberately opposite opinion to Dannyp, but I find when I do mine it's best to come in with the heat very slow and try to keep the welds as cold and as shallow as possible, as the deeper you go the more porosity and contamination I seem to find unless it's a really mint casting if that makes any sense. Use a bigger tungsten than you might for clean shiny new material and give the machine some positive if you have balance adjustment (this will give more cleaning action and will help to naturally reduce penetration). If you have access to an oven big enough to get the casting into then a healthy pre-heat can work wonders, it helps to soften hard oil deposits too if you're struggling. I like to get mine between 100-150 deg C if I can.

If it all starts fizzing and going black on you stop don't add more power it will just get worse as it's obviously contaminated, let it cool a little, clean the crap away with a die grinder/rasp and go again, often the aluminium is of very poor quality and will be a sod to weld, but once you get a decent bit of fresh metal in then you can build or overlay as normal. (It takes a long time to build up with 4043 as it's lower melting point and tends to sit a little flat, if it's a big build up to do I often cheat with some 5356 as it seems to freeze faster, anyway it works for me)

 

[hotrodder]

Ally castings are virtually always highish silicon as it helps castability, the most common automotive flavours being AlSiMg and AlSiCu [/gross generalisation]. Virtually all ally welds are dissimilar to some degree in that (pure ally aside) it's fairly rare to use a matching wire due to solidification cracking. Any old chunk of wrought ally will be fine although the 5xxx series (AlMg) are best avoided where possible- they're not the best choice for things that'll see elevated temp service and magnesium silicide (the hardening mechanism used in 6xxx series heat treatable flavours) is fairly prone to solidification cracking

As said casting quality varies some with some stuff being so full of crud it might as well be cast from old cat food tins. As Jim i tend to sneak up on it initially... clean, warm then see how it pools, what boils out etc. Sometimes they literally 'bleed oil' like this example which is an ancient oil-water heat exchanger housing off a boat that's currently sat on the welding table



I was expecting far worse on the oil front but all those little black marks are oil seeping out. It had sat in degreaser for over a day before being pressure washed and, corrosion aside, was spotless until heated. The weld at 11 o'clock was corrosion that'd holed the thing and needs grinding back to reveal the porosity and then correcting. The bit at 1 o'clock despite not looking as bad initially (after a clean up with a burr) is just turning to dust when you strike an arc i.e. forget arc wander, the arc just stutters and blows out. I can see that area doubling in size before i get something close enough to ally to take some wire. Once that's done i've got the soldered copper heat exchanger core that fits inside the bore to repair- oil passes from left to right of the pic with water flowing through axially

 

[lchris21]

I just welded up some holes in the alloy EGR valve on me motor as part of an intake mod. These EGR valves can get very, very cruddy indeed. Mine was no exception.
I scraped off all the excess then let it sit in traffic film remover overnight. Rinsed it out thoroughly the following day and let it dry. Give the holes a wire brushing then set to with the TIG.
I used the pedal to skirt around the circumference of the holes, building up the power while the crud bubbled out. When I got to nice shiny metal I introduced the filler and away to go. Took a few circumnavigations of the holes, but you can see the crap coming out during every pass.
my tuppence worth...

 

[dannyp]

Not to take a deliberately opposite opinion to Dannyp,

diffrent people find diffrent ways of doing things. i allways tend to use a lot of power unless for some reason i cant but i tend to start on higher power and work down rather than low and work up.


if the cast is really nasty as jim said i'll try the gentel approach with it but if it starts bleeding oil or anything like that if i can it gets attacked with the gas and or put it in the oven and keep it HOT so the oil has no choice but come out the pores then attack it with SS wire brushes ether by hand , grinder, drill.

i've also had results from soacking things overnight in thinners then gieing them a quick warmup to something like 60 ish degrres to drive al the thinners off.

most of the ali repairs i do are rush jobs, whoever brought it in is usally stood around waiting untill it's done hence why my methods may seem inpatient