Project: Repair of Broken Metal Casting.

[Andrew 2.8i]

Is it possible to repair an a metal casting using a liquid metal epoxy?
Here is my attempt at such a project.

This is the item in question, the thermoswitch housing from a 2.8



It mounts at the front of the engine onto a flat plate. The two flat faces mount together



This explains why the joint was leaking.



Closer inspection reveals the problem. Sorry for the out of focus photo, I was using my tablet for the first time. This must be a common fault as it's the third time I've seen the exact same problem.



Time to take the plunge to start the repair.



I cleaned up the two edges of the break, lightly brushing it with a pencil wire brush to remove any dust.



The I degreased both surfaces with my potion of choice.



Test the fit of the two bits.



I used quick set Liquid Metal epoxy by Sealey.



Two equal sized dollops.



Unsurprisingly, black and white mixed make a grey goop.



I applied a thin layer to each surface.



And joined the pieces together.



To ensure that the repair was flat, I temporarily mounted the thermos switch housing onto the plate, with a layer of plastic so they don't bond together.



After a bit, and it didn't take long as this stuff really does dry quickly, it was ready. The excess liquid metal was sanded off. As you can see, both the lugs needed to be repaired as both ends of the casting were cracked.



It looked much flatter than it did originally.



It seems to fit together OK when the gasket is in place. Perhaps a little smear of sealant will also help when it's reassembled.



I also used the liquid metal to build up some missing sections on the lip that the rubber hoses fit over.



To finish off, I could either polish the housing, or I could paint it silver. I've opted to paint it as the finish will last longer than polished bare metal. I'll post a photo tomorrow when the paint is dry.

I don't know yet if the repair will be satisfactory, time will tell.

Andrew.

[Jasonmarie]

Yes you done a great job there but I am worried it might go when hot ? Perhaps before you paint to boil the kettle and leave in hot water for some time . Only a thought as there will be pressure there as well .
Be interested how this goes as I have used JB weld on clock faces and I know it can reach high temperatures but never tested this side of the cold weld .

[Taff50ish]

Hi Andrew,

In my past life as a welder, I used to have to TIG, Ally cast chain hoist covers, quite frequently. I used a 5% mag rod, even tried 5% Sil rods, actually a whole selection of mixes , but Ally cast is full of air holes and its very dependent how good the quality of the cast is, how good the repair is. You end up chasing air holes for days (a bit like chasing rust with a MIG on a chassis) and inevitably you end up cutting, welding, grinding back and start again up to 6 times for poor cast. You can get a good repair on the surface, but they would eventually fail where the weld joined the cast (these where chain hoists thrown in and out of road cases every night on a 5 month tour, so very badly treated). So with not knowing much about the chemical glue you have there, I'd go with 'suck it and see', I'm afraid... But I wish you the best of luck with this and please do let us all know how it goes? As we might need to try this trick eventually... Cheers Andrew, keep safe,

John...

[Peter-S]

I did repair the housing on mine like that when I was restoring the 2.8 right at the start but came across a reasonable replacement before I fitted it so I'm none the wiser as to how strong it would be as it still sits in my spares box. What I would say Andrew is that whilst you have a nice neat repair there I feel that building up a layer of chemical metal to overlap the crack (obviously not on the underneath) might give a bit of added strength as you only have a fairly narrow bond at present. I know it would look less neat but as you are painting it anyway you could probably disguise it to a degree. Just my thoughts anyway.

[Andrew 2.8i]

Yes you done a great job there but I am worried it might go when hot ? Perhaps before you paint to boil the kettle and leave in hot water for some time . Only a thought as there will be pressure there as well .

Hi Jason,
Thanks for your thoughts on this. The pressure of the cooling system when hot is somewhere around 13-15 psi, it will be interesting to see how the repair holds.

Ally cast is full of air holes and its very dependent how good the quality of the cast is, how good the repair is. You end up chasing air holes for days (a bit like chasing rust with a MIG on a chassis) and inevitably you end up cutting, welding, grinding back and start again up to 6 times for poor cast. You can get a good repair on the surface, but they would eventually fail where the weld joined the cast

Hi John,
Again, thanks for your thoughts on this. It did cross my mind that the casting may not be the best quality, but then all of these casting will be the same.

But I wish you the best of luck with this and please do let us all know how it goes? As we might need to try this trick eventually.

I think we will eventually. What made me try a repair was that I noticed there was just one thermo housing for sale on Ebay for £80 and guess what? If you zoom in on the photos one of the lugs has a hairline crack. Good ones are hard to find now.

I did repair the housing on mine like that when I was restoring the 2.8 right at the start but came across a reasonable replacement before I fitted it so I'm none the wiser as to how strong it would be as it still sits in my spares box.

Hi Peter,
Thanks for your thoughts on this. Luckily, I too have one last thermo switch housing that I will be putting on the car, and two that I was hoping to repair and keep as spares in case they are needed. It seems a shame to just throw these away when they develop cracks.

What I would say Andrew is that whilst you have a nice neat repair there I feel that building up a layer of chemical metal to overlap the crack (obviously not on the underneath) might give a bit of added strength as you only have a fairly narrow bond at present. I know it would look less neat but as you are painting it anyway you could probably disguise it to a degree. Just my thoughts anyway.

Good point, I'm just a sucker for neatness at the expense of functionality!

As these are easy to replace, I might try one of the repaired housings when I intend to not stray too far from home. It would be good to get a definitive answer as to whether the repair is able to withstand the heat and pressure of the cooling system.
Thanks again everybody for your advice and opinions.

Andrew.

[stevemarl]

Andrew,
just wondering if, now all the parts are firmly in place, would it be possible to drill some 2mm ish holes through broken pieces into the `body` so you could put pins in it to strengthen the repair? I`ve used rollers from a needle bearing / bits of old drill etc in the past - they`re very hard and rigid for their diameter.

[Andrew 2.8i]

Andrew,
just wondering if, now all the parts are firmly in place, would it be possible to drill some 2mm ish holes through broken pieces into the `body` so you could put pins in it to strengthen the repair? I`ve used rollers from a needle bearing / bits of old drill etc in the past - they`re very hard and rigid for their diameter.

Hi Steve,
Thanks for your advice. Yes, I think that is an excellent idea and worth investigating. I'll see what I can find to use and I'll give it a go tomorrow.

Andrew.

[stevemarl]

Just in case you can`t find anything suitable, I`ve got a load of these if needed, very, very strong, 2mm diameter by 13.7mm long? Maybe not long enough though?

[Andrew 2.8i]

Just in case you can`t find anything suitable, I`ve got a load of these if needed, very, very strong, 2mm diameter by 13.7mm long? Maybe not long enough though?

Thanks Steve.
I think I might give the strengthening pins a miss for the moment, although I'm not ruling it out in the future. I tried to snap the repaired bits off by hand but couldn't break it. I know that approach isn't highly scientific, but I guess the liquid metal bond might be strong enough on it's own to withstand the pressure of the cooling system?

Andrew.

[Caprifan Rob]

That repair looks excellent Andrew. They Have used Devcon liquid metal in the airline Industry. I know it’s a different make but principle is the same. If it’s good enough for that your repair should hold ok. Good luck.

[stevemarl]

I understand what you`re saying Andrew, but of course you couldn`t have snapped the alloy casting when it was new, but that failed..., it`s the repeated strain (and the cycling of) that eventually causes the stress fractures. I would consider at least putting the part in a pan of boiling water and checking it`s integrity when at working temperature before testing it on the road, as I`m guessing failure would mean a sudden loss of water?
Edit: FWIW, I`ve found that Araldite for eg, comes in either the `old style` which takes hours to set, or a quick setting version, which is useful if parts need holding in place but is ultimately not as strong as the conventional resin , and seems to soften more with heat. Obviously this is just my perceived experience but just thought I`d throw it in anyway?
I feel I`m going to be seen as really negative but that`s not my intention at all, I just worry it will fail in service miles from anywhere...
Edit, edit: just thought, as it bolts onto a flat plate, could you not use resin all the way around the faces so that the whole body is fixed to the plate rather than just an `ear` at either side? That could improve strength dramatically, but I`m unfamiliar with the part so may not be possible?

[Andrew 2.8i]

I feel I`m going to be seen as really negative but that`s not my intention at all

Hi Steve,
All advice is gratefully received. You're not coming across as negative at all.

I`m unfamiliar with the part so may not be possible?

Sorry, I've just realised I hadn't given any indication of the size of the part and where it is located.
To give some idea of the scale of the part in question, I've drawn up a template of the surface area of the base, I've drawn on the fractures to show them in relation to the edges.





Hopefully the following photo shows where the part fits in relation to the engine.



Andrew.

[Andrew 2.8i]

That repair looks excellent Andrew. They Have used Devcon liquid metal in the airline Industry. I know it’s a different make but principle is the same. If it’s good enough for that your repair should hold ok. Good luck.

Thanks Rob,
We'll just have to wait and see if it holds as it is or if some further strengthening is necessary.

Andrew.

[Andrew 2.8i]

as it is or if

Five consecutive two letter words in a sentence, is that a record?

Andrew.

[Paul G]

That engine looks better than new. Lets hope your repair holds and as as said earlier withstands the expansion and contraction when the engine is hot then cold.

[stevemarl]

That engine looks better than new.

It IS outstanding, I have never seen one so clean and original!

[Andrew 2.8i]

That engine looks better than new.

That engine looks better than new.

It IS outstanding, I have never seen one so clean and original!

Thanks Gents!
As it happens, it's what I'm working on at the moment.
I've encountered some setbacks though which are hindering progress.
1. The baffle in the sump has snapped off at the welds. I'll have to try and find somewhere that is open to repair it before the sump can be painted and put back on.
2. The enamel paint I've chosen to paint the engine, VHT Ford Gray (sic), seems to be out of stock everywhere and I haven't got enough left to finish the job.

Andrew.

[Paul G]

Wish you were nearer, I'd soon weld that sump up for you.

[Jasonmarie]

That engine looks better than new.

That engine looks better than new.

It IS outstanding, I have never seen one so clean and original!

Thanks Gents!
As it happens, it's what I'm working on at the moment.
I've encountered some setbacks though which are hindering progress.
1. The baffle in the sump has snapped off at the welds. I'll have to try and find somewhere that is open to repair it before the sump can be painted and put back on.
2. The enamel paint I've chosen to paint the engine, VHT Ford Gray (sic), seems to be out of stock everywhere and I haven't got enough left to finish the job.

Andrew.

Engine looks fantastic Andrew i have no VHT ford grey in the shed But it’s a great colour . Hope you get the sump sorted

[Andrew 2.8i]

Wish you were nearer, I'd soon weld that sump up for you.

Thanks Paul.
Hopefully some local places will start to reopen soon......I hope!

Andrew.