cast welding advise

[powernut]

bit tricky as ive a cracked engine block which is either cast steel or cast iron unsure which tbh ,
can this be tig welded?
as i once remember i tryed warming a cast crack up to gas weld it with a cast rodand it cracked furthur , if its not a good idea , not to worry as i do have another block to rebuild from as i heard differnert ideas but need a bit of export advise ,,,

 

[rtbcomp]

Drill a small hole at each end of the crack to stop it spreading.

 

[powernut]

Drill a small hole at each end of the crack to stop it spreading.

good point i know it grinds and drills ok and also has orange sparks wheather that may help decide what type of cast it is im unsure , as i need it to seal as water sits in the engine block , but last thing i need is build the lot up and refit to find water leaking ,,,

 

[hotrodder]

Yes, depends a lot on crack location as to viability/economics of repair but if you've a spare block i wouldn't bother. Not an easy job, not one i'd be looking forward to and the nickel wire is far from cheap

As to it leaking afterwoods... Obviously a fair bit of work to block off waterways for a hydrostatic test. Can you produce air tight welds consistantly? Can be easily and cheaply tested with dye pentrant (search the site, several threads about the stuff) to reveal flaws.

 

[rtbcomp]

You could try stitching instead.

Basically drill a hole at the LH end of the crack, tap it and screw a piece of threaded rod in the hole, cut off & grind flush then drill another hole centred on the intersection of the crack the RH diameter of the rod. Repeat until the end of the crack is reached.

It may be advisable to use loctite on the threaded rod.

 

[Tino]

With orange sparks I think it will be a cast steel but probably a nasty mix for welding. I would go for a dissimilar E312.

 

[hotrodder]

Opps missed the spark colour last night. 312 certainly a lot cheaper and i guess nothing to lose if you've a spare block. Another one i didn't think of last night was brazing. Depends where the block is cracked but might be the way forward if you really want save it...

 

[powernut]

cheers guys nice to know theres some great advise and very good detailed help, ive decided to strip the block and rebuild into another as i was only haveing a play as i class it as scrap i tryed tigging it with stainless i thought thats gone really well and got some decent runs on it to find out it cracks clean thought the stainless , lol so tryed a few differnert types of metals for trail ideas found some arc rods ant a clue what these are but tryed one as a filler rod and hasnt cracked? still just a silly idea i supose