Arc weld a cracked block with nikel rods?

[SharpeCon]

I have a Mercruiser 4.3L V6 I/O, found the dreaded 3 inch crack in the valley behind the rods. Did some research & found that you can arc weld the crack with nikel rods, after of course you grind it down , cut a v, clean it up with acetone and drill the ends of the crack to prevent futher spreading of the crack, Then after the weld, smear it over with some good ol JB weld. has any one heard of this or had any success with it? Just dont have the money or time to replace the block...

 

[dr_bowtie]

Re: Arc weld a cracked block with nikel rods?

you'll be better off just using JB-Weld and going with that or an Industrial strength epoxy...

the problem with welding is it can be done but with very little success...

to properly do it you need to put the block in a furnace and get it up to a temp like 500degrees and then weld it and then put it back in the oven and SLOWLY cool it down over a long period of hours...

the problem isnt welding it but cracking as it cools...cast cracks when it cools when welded...and sometimes you can aggravate the weld and make the crack worse....

as I said I would just epoxy it and run with it...

 

[howlnmad]

Re: Arc weld a cracked block with nikel rods?

I have done it with success but as the dr stated it is important to do it correctly. The prep work, the heating prior to welding, the slow cooling process and it should be peened afterwards. I'd go with the epoxy as long as it's not a stress area. jmo

 

[cr2k]

Re: Arc weld a cracked block with nikel rods?

I have welded cast iron successfully with nickle rod. The trick is (not having all the furnace and stuff) is only weld an inch at a time and peen this asap while it is still kinda soft. This will allow it "fit" and de-stress and if done right it will not crack. Also by doing it this way you won't need to strip the block.

Good luck with what ever option you choose. Let us know what you did and how it worked.

 

[bigskiohio]

Re: Arc weld a cracked block with nikel rods?

at work the guys preheat area to 450 then weld then cool it slow by holding the heat in with welding blankets and sand bags

 

[jtybt]

Re: Arc weld a cracked block with nikel rods?

I mig (fluxcore nickle) about 3/8-1/2" at a time when welding closed the water passages in the exhaust manifolds without an oven. It still cracks and you have to grind and re-weld the cracks along the edge of the weld...and peen

 

[SharpeCon]

Re: Arc weld a cracked block with nikel rods?

Well I had the crack in the galley arc welded with the nikel, he said he knew to cool slowly and peen. He was confident it would hold, I did smear it over with jb weld for insurance. There was also a crack on the water jacket of the exhaust mani, welded that too. Another crack on the lower portion of the block, he could not get at that one, so I sanded it cleaned and jb welded it. My gosh what the heck did the previous owner do to this boat! Freeze cracks, heat cracks, I wonder if there are more cracks I cant see?!?! Damn I hope this works! I am going to put it all back together before the weekend, drain the oil 2-3 times, get it clean and try it out!

Can someone tell me the best product to clean out the inside of the galley, looks a lil dirty in there, must be gasket pieces, metal shavings and what not, doesnt look to bad, it needs washed & cleaned out for sure. Also, while I have the manifolds and risers off, they appear to be quite rusty inside the water jackets, should I clean those up too and what to use on them? Thanks for the help guys!

 

[marlboro180]

Re: Arc weld a cracked block with nikel rods?

I mig (fluxcore nickle) about 3/8-1/2" at a time when welding closed the water passages in the exhaust manifolds without an oven. It still cracks and you have to grind and re-weld the cracks along the edge of the weld...and peen

????

 

[cr2k]

Re: Arc weld a cracked block with nikel rods?

About the best you can do on the manifolds is rod them out and blow them with air or flush with water. Just use a rod or long skinny screwdriver and loosen up as much rust and scale as you can. You will be amazed at how much will come out.

 

[fabrimacator21]

Re: Arc weld a cracked block with nikel rods?

YOu don't need to spray anything to clean it.... a wire brush wheel on a grinder for the surrounding areas and a hard rock grinding wheel for the crack itself works great. Most of the time spraying anything on a surface to prep it will cause peroscity/air in the weld which is why I alway grind on/wire brush whatever needs to be cleaned.


As others said... preheat... weld... peen.... then cover with welding blanket. You'll be fine.

I don't know about mig nickel wire... never heard of it and ARC is stronger then mig.

I like to use a center punch and a hammer to peen. Have your hammer and center punch ready to go as soon as your done welding. The sooner you peen it the better off you are.

YOu may have to run one pass to get all the sand out (****ty cast) grind first weld out and weld it again. MAKE SURE you get all the flux out if you run more then one pass... slag hammers don't usually get all the flux/slag out so you might want to do a little grinding to be sure you got all of the flux out.

I wouldn't use anything but weld.... epoxies will hold up for a little while but if it starts to come apart then you have little chunks of epoxy in your motor and I don't see them being as strong.

You don't need an oven either.... a regular butane(handheld bottle torch) or oxy acetalyne torch will work just fine. Make sure you heat up a good area though, meaning heat it up a good 6 inches or more around the crack. You need to get it to atleast 450 degrees. YOur better off if you get it and the surrounding areas good and hot(over 450) and letting it cool down... this lets any surrounding metal(and metal on the other side of the crack) absorb the heat evenly... when it gets close to 450 while cooling, weld away. You can even put a little heat on it to keep it from cooling too fast after welding.

Make sure when you "V" or grind it out that you go beyond the end of the crack.... alot of times cracks are too small to see with the naked eye at the beginning/ends of the cracks.

 

[SharpeCon]

Re: Arc weld a cracked block with nikel rods?

Ok thanks for the advice on the weld and cleaning the mani, although the weld is complete, the welder did exactly as you described with the hand held torch and peening ect. What about washing out the glley of any debris? I have to change the oil a couple few times anyway.

 

[SharpeCon]

Re: Arc weld a cracked block with nikel rods?

Also while I have the carb off, should I soak it's parts or clean it in anyway?

 

[SharpeCon]

Re: Arc weld a cracked block with nikel rods?

?Anyone?

 

[jtybt]

Re: Arc weld a cracked block with nikel rods?

With that many cracks, I think you engine is pretty much toast. You're only describing the cracks you can see. Generally, cracks in exhaust manifolds aren't worth welding because it's just as likely to have internal cracks, too.

Unfortunately, you may have to re-power. Should have had some look the boat over before you bought it.

 

[SharpeCon]

Re: Arc weld a cracked block with nikel rods?

I Bought the boat, not knowing anything about boats & it was out in the middle of no where on a sunday. Thats a shoulda woulda coulda, didnt, too late now! Granted there may be more cracks, I'm hoping not, & what do I have to lose now? A otherwise worthless boat sitting in my driveway taking up space! Really though, I sunk another 150 into it for the weld, & it IS possible it is fixed now,

I was only looking for a solution to cleaning out the galley? Not any more opinions on the crack, thats a done deal for now. Oh and if I should clean out the carb while its off?

Thanks

 

[marlboro180]

Re: Arc weld a cracked block with nikel rods?

Clean the carb right now? If you know how to do it thoroughly, have the gasket kit, etc. then sure, why not. Otherwise when you put this old girl back together you may just be adding one more variable at this point.

 

[IVAZ]

Re: Arc weld a cracked block with nikel rods?

I'm not a fan of repaired blocks so I dont have any advice on that front.
It seems like you are trying to do this on a budget. If thats the case have you considered an engine from an auto junkyard? All you have to do is find one off a low mile wrecked truck. Just something to think about if this doesnt work for you and you want to get in the water cheaply.

 

[Bondo]

Re: Arc weld a cracked block with nikel rods?

What about washing out the glley of any debris? I have to change the oil a couple few times anyway.

Ayuh,... Use Diesel Fuel,+ a stiff brush,.... lot's of Diesel...

And,.. Yes, rebuild the carb now is a Good Idea...

and ARC is stronger then mig.

Ayuh,.... Bullship.....
Nickle rod don't care How it's applied,... You can even Ox/ Ac it in place.... A Bead is a Bead...

 

[SharpeCon]

Re: Arc weld a cracked block with nikel rods?

Ayuh,.... Bullship.....
Nickle rod don't care How it's applied,... You can even Ox/ Ac it in place.... A Bead is a Bead...

Are you saying nikel was the way to go?

 

[Bondo]

Re: Arc weld a cracked block with nikel rods?

Are you saying nikel was the way to go?

Ayuh,... Nickle is the filler of Choice with Cast Iron...