Epoxy casting repair?

(Posted separately to uk.rec.engines.stationary)

I've got a badly corroded cast iron gearbox casing to repair. It's the reducing gear from a Lister JP marine. These have a water cooling jacket, superfluous on a 21hp JP2, but this one has evidently suffered from a past life with salt water passing through. One side of the water jacket literally fell off recently, and the owner was complaining that it was leaking oil. I've ground off most of the remaining water jacket, to get at what was behind. After removing loads of scale, I'm left with gearbox side walls which are paper thin in places, and perforated on one side. There should be enough mechanical strength left in the webs through which the retaining bolts pass. I reckon the only satisfactory repair will be by getting it grit blasted, & then coating the sides with epoxy. Welding is, to my mind, out of the question. Any suggestions as to what is a good epoxy to use? Or should I just bite the bullet & contact the local Belzona rep, with the consequent emptying of wallet?

Cheers

Tim Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Reply to
timleech
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I once stitched a cracked Land Rover cylinder block with JB Weld and never had to attend to it again. Expensive stuff though - I'm sure there must be an 'industrial' equivalent available in bulk at a cheaper comparative price.

Regards,

Reply to
Stephen Howard

Could a new side plate be fashioned out of steel or ally and bolted on with silicone sealer? I'm not sure if chemical metal would work over such a large area but you never know.

Reply to
Dave Baker

How about sheathing it in fibre glass, preferably using woven rovings for higher strength.

Reply to
Jonathan Barnes

In article , timleech writes

Tim, there's a bloke on Ebay who flogs Belzona off at reasonable rates quite often. Might be worth a search.

I've got a pot here "against the day".

Reply to
Nigel Eaton

Tim,

I have had good results in the past with Devcon sticky products for casting and structural repairs:

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I've mainly used the aluminium loaded one on castings for cosmetic repairs but I've also used the 'hard wearing' and the ceramic filled ones on bearing housings. I have the remains of a tin of the aluminium one that is over twenty years old and amazingly STILL works though I'm sure that the quoted shelf life is far less than this

Andrew Mawson

Reply to
Andrew Mawson

I'll second the Devcon products, I use them for mould making, in our injection moulder, so they stand high pressure and heat. JB weld gets used too, but Devcon sell in larger packs. Do you have a Cromwells industrial supply near by.

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Joules

Reply to
Joules

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And use an epoxy resin instead of a polyester one, which should result in something probably stronger than the original cast iron.

Dave.

Reply to
speedy

Might be worth having a word with Strand Glass (in Brentford, Middx still?)

They do a wide range and I've always found them very helpful. Might be worth doing epoxy with powder metal filler. Araldite used to do one in small quantities which could be machined and tapped

In message , speedy writes

Reply to
Martin Akehurst

I did a very successful repair to a mini sump that way, years ago, after I smashed a hole in it. Lots of 1/4" whit or similar holes tapped around the edge, ally sheet bent round the front (The hole was on the front edge, of course) & silicone sealant behind it. Lasted until I got rid of the car a couple of years later at over 100,000 miles. The ally swarf in the sump didn't seem to do it any harm

Something similar would be difficult here, though. The corroded sides are maybe 3.5" deep, thin over the whole depth, & the thin area wraps right round the bottom & up both sides, so the thin area is of the order of 25" x 3.5", with two 90deg bends & various deformities, and nothing to fix the edges to.

It's too thin to weld, in theory you could let in some new bits of plate & weld them in place, but the amount of welding needed would be bound to distort it far too much to be useable.

The one other possibly practical suggestion would be to get someone to stitch some new bits of cast into place, but the price would probably be a bit frightening.

I would trust epoxies to bind much more durably to the cast than typical glass fibre resins.

The owner has managed to find a replacement casing, after the 'man most likely to' just laughed when I asked if he had one. Trouble is, they want 400 quid for it :-( (secondhand) so he's thinking about it.

Thanks to all for their suggestions.

Cheers Tim

Reply to
Tim Leech

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