Help! How to fix crack in engine block

[topmast]

Mike, thermite is lots of fun welding rail tracks (gravity and position is everything) also pretty good if terrorism is your bag. (the monkey wrench gang)

[sailingfarmer]

Sorry...everything mentioned is a temporary fix ..... time for a new engine block

[Cadence]

Originally Posted by sailingfarmer

Sorry...everything mentioned is a temporary fix ..... time for a new engine block

I fear sailingfarmer is right.

[bsurvey]

clean the area really well with acetone then apply JB weld held place with electrical tape, the jb weld will not stick to the tape

[SV Bacchus]

Originally Posted by Cadence

I fear sailingfarmer is right.

Agreed! The question is "what is your life worth?" I believe, and some would argue with me, mine is worth more than the cost of a proper replacement.

[TurninTurtle]

Generally... a cracked block is going to keep having problems regardless of how you try to fix it.

Expansion/contraction tends to break the repair. Drilling the ends of the cracks is to hopefully prevent the crack from growing. If you don't actually drill at the end of the crack... you did ZERO good.

Cast iron tends to crack right beside a weld. The material in the weld will never have the same thermal expansion ratio as the original casting.

Epoxies tend to crack loose due to difference in thermal expansion.

You might be lucky and it work for years. This is far more rare than the repair failing within a few cycles of heating and cooling due to normal operations.

As I said... its problematic at best.

Sure... try the repair. At least it can make it work for a while.

[tkeithlu]

This all sounds "On the ragged edge" to me. If this really is a rust through, a repair leaves a lot of other spots ready to rust through. If this is a crack, what caused it? A true repair is going to require an engine disassembly, so a replacement used block may be a better choice than a repair that leaves unknown problems behind. As for welding cast iron, I had the folks at Lodge cast iron (the frying pan makers) shake their heads at repairing a crack of mine, and the owner had asked them to do it if they could.

[Reefmagnet]

If the repair area has been soaking in oil nothing, especially epoxy, will successfully seal the leak. If you can clean the joint up properly (which would probably mean pulling the engine out at a minimum) then repairing with metal is the best option. Usually nickel alloy welding electrodes specific for cast iron welding are used for arc welding without the need for preheat (this is how the engine makers would repair the odd casting defect); or (actual) cast iron rods for gas welding or manganese bronze rods for brazing.

If you're lucky you might be able to do the quick and dirty fix with a screw, or even a screwed down plate and sealant if a small crack. At the other end of the scale, if the engine is worth saving and needs to be stripped down then there are businesses that specialise in this type of repair of cast iron blocks and heads, which should work out cheaper than a new block.

[CatboatWilly]

I can attest to the fact that Marine-Tex does hold up to very high heat. A little story;
At our ice boat club we have several cast iron 'cannon ball' type wood stoves. We'll, one year some unknowing soul put coal in the to heat the place and two of the stoves cracked from the excessive heat as coal burns much hotter than wood.
We patched the cracks up with Marine -Tex. That was 15 years ago and they are still going strong.
Love the stuff !

[Sailuke]

It seems to be a small hole, not a crack.

[Jsta_Rebel]

Like I said, 850 psi and the valves held. Also 160 degrees on my aluminum expansion tank was not an issue either. you may not have mixed right. Marine tex sticks to metes better than anything I have ever tried. However, I would agree with the poster that stated that all of these remedies are temporary fixes, and a new motor, or new block would be best.

[sanibel sailor]

oil pressure switch is in that area. Can you see the leak?

[dmalcol1]

Ok so we assume you are in a bind and need to get vessel back to home port to make good on repairs.

My two cents!

Toothpick soaked in red loctite then jammed in whole let sit as long as possible, this worked for head gasket in gas engine that was leaking antifreeze.

[Compass790]

You can get some amazing cast-iron welding rods now that dont require peening & pre heating or post weld slow cooling for small repairs. They seem to chill out virtually instantly & you can put a bare hand on the weld immediately after welding. Sorry tho I cant remember the brand & specs. May have been Eutectic but cant swear to it. Try a specialist cast-iron welding place, they mite sell you a couple of rods. If the hole is small you will just be able to put a blob on the top no worries. Well I'd put a blob x2 or 3 .Get as clean as you can first tho.

[Steven Hunt]

Greetings from Melbourne Australia,
You need to purchase some "Belzona 1212" or "Belzona 1161" surface tolerant, two part repair material.
The 1212 is a fast setting grade and the 1161 takes about 18 hours to fully cure.
I distribute these products in Australia. I suggest you go to www.belzona.com where you can view some information on the product and be directed to your local distributor who will provide you with both product and expert application advice.

Best wishes,
Steven Hunt