Cracked Gearbox - disaster!

This was a Ford Escort gearbox which had been cracked underneath & was leaking oil. It was brought to us complete (just the gearbox, not the whole car!) & still with oil in it
Could we weld it up?.......
One problem was that we didn't know how thick the casing was so couldn't run the risk of using too much power & burning a hole through the casing & couldn't grind out the cracks for fear of going through. That exacerbated the main problem, that the cracks were dirty/oily & that though the outside of the casing can be cleaned, the inside of the casing was still oily. Welding over the cracks just drew the dirt & oil out & contaminated the weld.



This can be seen here as sooty discolouration & holes in the weld.

Sometimes you can get away with it by cleaning the surface again & grinding the weld off and going over it again. The "dirt" floats to the top of

the weld pool so it gets removed when you grind the weld off (in theory - if it's not too bad).

In this case, the contamination just kept coming through.

The weld continues to grow & still keeps cracking.

The final complete mess! Full of holes & craters. Still cracked, still leaking - a complete waste of time.

The correct way to do this would have been to strip the gearbox completely so that the casing could be thoroughly cleaned inside & out, the cracks could be ground out to remove any dirt/old oil in them & it could be welded on both sides to ensure a good weld. Then rebuild the gearbox.

But that would have cost more than buying a secondhand gearbox, which is what the customer ended up doing & we should have told him to do in the first place!

You live & learn.

Air Conditioning Pipe

This pipe is from an air conditioning system on a car. The engine mounts had collapsed & allowed a pulley to contact the pipe & wear it away. When brought to us, only a pinhole was visible in the damaged area, but a poke with a scriber soon revealed how much of the aluminium was worn away & not just dented.

Even if the problem had been just a tiny pinhole, the repair would have been done the same way:-

Cut a little patch from sheet aluminium & TIG weld it in position all around the damaged area.

Trying to weld over the hole just vapourises the fluid remaining in the pipe which then contaminates the weld. Using a patch gives a much better chance of getting a good weld with no pinholes (& leaks). Even so, extraction is needed to suck away the fumes that come out of the end of the pipe & in this case, the rubber hose which is clipped to the aluminium pipe was put into a tub of water to keep it cool while the welding was being done.

Bell Housing Modification

This was a fairly simple job. The customer brought the bellhousung to us with the Aluminium block clamped in position. This was needed to attach a non-standard clutch release mechanism. The parts were in a nice clean condition, so it was a case of switch the TIG welding machine on, turn up the amps (about 200 to start with), put 3 big tack welds on to hold the block in position, remove the clamp & weld around the join. It needed to be repositioned several times & access was tight in some places, but we managed to weld all the way around the block for a good strong join.

Waterjet Drive Unit (Boat Propulsion)

This Aluminium casting is part of a waterjet propulsion unit for a fairly sizeable boat. The inside had corroded to such an extent that it had created a hole through the side. First step was to clean off the paint around the hole.

Then an Aluminium plate was welded over the hole.