Gents, need expert advide please.

Can't find anybody here in France prepared to replace ruined push rod tubes. I can’t find the tools needed which is tube expander. Decided to cut the aluminium tubes and perhaps weld new tips on but I am having great difficulties getting the aluminium to bond on the push rods tubes. Also the original tube and the reproduction tube melts at different temp. the original tube melts faster then the other. What do I do wrong. Suddenly I can get the stick to bond but only on one side but at the same time the tube melts on the other side. I did learn this at trade school dinkies’ years ago. I’m doing this out of shear frustrations over not finding anybody to replace the tubes.
Can anybody help please?

Hi, I've never tried proper aluminium welding, but have used this stuff on one occasion to successfully mend several grands worth of Italian bicycle frame (nervewracking). Don't know if you will be able to find a distributor near you, just an idea.

http://www.techno-weld.co.uk/home.html

Thanks for the link. Deiced to give up and to find some professionals. Been on the phone and finally found one company willing to look at it. Must others said straight no. What happened to good old trade skills are they disappearing? Aluminium is mighty difficult to weld, melting at around 660 degrees. Not easy to control

Aren't the pushrod tubes shrink-fit into the head? Wouldn't it just be easier to get complete new tubes made up and fitted?

One trick is to heat the head and freeze the push rod tubes, but I've seen them come un done + they can leak oil aftewwards despite using nut lock. They are secured with the tool called tube expander but nobody has it.

Given that ally welding is a pretty tricky business at the best of times its doubtfull that anyone is going to weld that sucsessfully. Ran it past my mate who has a precision eingineering and fabrication business...and he say "Nope"
"as the two parts of the tube have different melting points they are two diffrent alloys( something to do with numbers and silicon ) and even Tig with gas purging there is likley to be stress cracks as the weld cools.....if you got a decent pool going in the first place"

"not saying its impossible just going to take a lot of trial and error to find the right filler rod or take samples of the parent metal for analasys"

he knows his stuff, makes secret bits for the US navy

And the cost of one of his welding specialists... £150 for a new head seems cheap!
how bad was the tube before you burnt your bridges and cut it off?

never had one yet that was beyond fettling.

Sean

Settling in France, I would like to offer reconditioned heads on our web shop (exchange deals) + be able to fit proper reconditioned heads on rebuild engine which I’m getting my teeth it to, when all my home work and running around is sorted. After a very long time, we managed to find a decent engine builder and organized 8 heads to be re done. We supplied new valve guides, exhaust/inlet valves and new push rod tubes. Most tubes have damage to the tips. Common problem when DIY are replacing the push rod seals. Some tubes have pin holes half way up, most likely from hand tools. One head dropped on the floor and tube snapped in two. The firm cut the tubes to remove them and realized that a tube expander is needed to fit the new tubes correctly and gave up after looking at the Citroën work manual we supplied for them to see how to and to position the tubes spot on 71 mm from the face.
Got the heads back with a note sorry can’t do the tubes. There you go. Just come back from an engineers shop working with aluminium welding every day but he did shake his head when he discovered how skinny the tubes are. He spotted the difference in material straight away between the original and reproduction tubes but he’ll give it a go. I know next week what the outcome is and will post the result here, hopefully with a couple of photos.
Over the years I have exchanged and collected many heads with damaged tubes. I don’t believe in just getting another head from the shelf. I want to recondition and preserve old parts. In order words bring back old skills and not just become a spare parts exchanger. The more I can do the better I feel. I do know my limitations and will ask other skilled trade people when my ability stops. Same for gear boxes and engines. Most reconditioned engines and gear boxes are really low standard jobs but that another story.
Cheers
Viking bastard

Got the heads back. Voila look at this. 10 € per tube, dirt cheap. Hopefully not leaking. No welding to be seen on the inside.

That's a skilled job to weld ally that thin, if it's leak free, and straight, then you're onto a winner. I haven't had the practice at TIG welding to do anything like that, but I know it's a PITA to weld ally!