Metal stitching

Now .. the ugly part is to open up these cracks and find out just how much thickness of metal we have to work with .. and just how much scale is still there. It's not looking good.

Despite the acid doing good work on most of the coolant passageways, there's still a serious amount of scale left .. right behind the cracks, of course! :

The problem we have here, is that the coolant passageways narrow down, virtually to a point, at the bottom.
The scale and corrosion has collected in these areas and has hardly been touched by the acid.
The fact that nearly all the cracking is right at the bottom of the coolant passageways, seems to indicate to me, that there was more than one problem causing the cracking.

The problem appears to be, that it was not only low temperatures involved .. but also the scale growing in these low points, and putting pressure on the casting.
As scale increases in a cooling system passageway, it "grows" in size. We've all seen thick rust expanding and pushing chassis rails apart. The same thing happens inside a block.

The bottom pic shows the LHS of the horizontal portion of the vee'd-out crack, with the scale still virtually solid, and about 1-1/2" in height, in the bottom of the passageways.
The RHS side of the crack shows where I've chiselled the scale out, and got through to the cylinder wall.

The hole that was already in one of the cylinders, under a valve port, had very thin edges, and therefore indicated a loss of metal thickness due to corrosion.

This hole had to be opened up, to get back to some reasonable thickness of metal.
I just tapped the edges with a ball-pein hammer until I'd broken the edges of the hole back to some satisfactory thickness of casting.

The hole needs to be filled anyway, so a piece of metal will be cut out to match the hole and welded in.
We can use mild steel, or cast, or anything that can be welded. These Magna rods will weld anything to anything, and it stays there.

This is getting to the really ugly stage. Here's the worst crack. It runs for about 3-1/2" around the cylinder wall, and about 4" vertically.

There's solid scale still packed behind most of this crack, and there's only one way to attack it, now. I have to open it up.
I feel like a doctor opening up a patient for an appendectomy .. and finding he has every artery to his heart, almost totally blocked .. :'( :'(

Tapping on the area around the cracking reveals that additional cracking is widespread, and nothing can be achieved without removing some serious chunks of casting around the cracks.
Accordingly, two chunks are knocked out of the cylinder wall, to reveal some major amounts of thick scale behind them.

The bottom pic shows clearly how the coolant passageways narrow down rapidly at the bottom, and create a point, where scale growth is a serious problem.

Chiselling the scale out and then pressure-washing again, shows that the passageway has cleaned up beautifully.

Once again, a piece of metal will be cut out to match this hole, and welded into it, to produce a perfectly acceptable repair.

Next week, the cylinders will go into the washing soda electrolysis bath, for a full clean up. This will remove all the residual corrosion, and allow weld repairs to be carried out on solid, clean metal.

Magna state that you can weld right over rust and oil and any other contaminants .. I prefer to work with clean metal, to ensure a repair that's as good as any professional operation.

The step after the electrolysis bath involves bolting the cylinders into a jig to prevent warpage, when welding. All welds "pull" when they shrink, and I don't want to risk warpage. More to come on that.

Dr Ron

Now thats what you call getting serious with it.

Pictures speak nearly as good as your words, keep us posted as this is going to be a very interesting journey.

Trevor

G'day Ron, or should your title be "Metal Surgeon"?

Thanks for a great bunch of pic's and report to date. We will be following this thread with great interest and fascination. You make some very good points about what happens inside a motor when rust becomes scale and starts putting pressure on components. I look forward to the next in-depth report.

Geoff

O.K. - I've finally managed to commence a serious attack on these cylinders. First job is to soak the coolant passageways with some mild hydrochloric acid solution.

I blocked off all the openings with pieces of tinplate glued on with Selleys polyurethane sealant, and covered all the cracks with it as well.
Fantastic stuff, sticks like the old proverbial you-know-what, to a blanket.
Then after I finished smearing it every where, I read that it contains iso-cyanates! Yes, the same nasty stuff that's in the hardener in two-pack polyurethane paint! Hmmm .. :

I know this doesn't look particularly professional, but it's the only way I can ensure the coolant passageways can hold the hydrochloric acid solution without it leaking everywhere.

We'll never make a bush mechanic out of you Ron :'(

A real bush mechanic would've considered the job done.
Once all the cracks were covered & glued up