Cracked block repair questions

[Dan]

My machine shop found two cracks in my 1939 9N block when I did the rebuild. Due to the rarity of the serial number, I decided to attempt to fix these myself. I did the standard "V"ing on the crack with a die grinder, brake cleaner, then slow cure JB Weld. The crack between the drain and freeze plug held up fine, the one at the very back of the block above the bell housing leaked after the repair. Tried all kinds of stop leak products - no help.

So - this morning I decided to wire wheel all the JB Weld off and attempt to silver solder it. Cleaned the area extra good, fluxed the bajeebers out of the area, then tried to solder the V'd out area. No matter what I did - I could not get the silver solder to stick to the cast.

I am no expert at soldering or brazing - so any tips or ideas would be appreciated.

Dan

 

[Anonymous-0]

Dan,

I hope you get a reply that lets you know the trick to soldering. Meanwhile - consider this option. <link>

Ray
Lock and Stitch website.

 

[Welding man]

Been in the welding business over 35 yrs.Never heard of anyone trying to silver solder cast. You MIGHT be able to braze it, but there are a lot of issues with that. Preheating to get the oil and anti-freeze out, the brazing it, post heating to not let it cool too fast and it cracking somewhere else,plus what will the heat needed to braze it do to the internals of the engine. I'd say you might have a 30% chance of success,but good luck.

 

[Dan]

I thought about that - but I think I should have done that before V'ing out the crack. Not sure stitching would still work now.

 

[Dan]

Yeah - normally you braze cast, but I do not have the setup or experience to do that yet.

Thanks,
Dan

 

[souNdguy]

yes.. you can solder cast.. however.. it's not as easy as soldering.. uh.. just about anything else.

To solder it I would clean well... wire wheel.. stainless preferably.. though regular steel wire will be fine...next.. got to get the jb weld resin out of the pourous cast.. might even have to burn it out with a propane torch.. then re-wire wheel.

Hit it with a soldering paste type flux like a radiator repair shop might use.. acid bse will likely help it stick much better than a rosin flux. ( some tractors have raditors with cast bases with the core soldered in! ).

next.. for this type of fix.. I like to do 'in position' soldering.. even though they should wet out of position... now on a tractor block in the tractor.. they may be hard to impossible to do. Preheating the area will also help immensly. Maybee try a different alloy solder .. even theat alumalloy stuff.. you can get it at most fleamarkets and northern tool and weld supply stores.. comes in 'sticks'..

If it won't stick.. either too dirty or not hot enough so far..

soundguy

 

[Anonymous-0]

Hello Dan,
I assume these two cracks are accessible. You can weld them with machineable cast iron welding rod using a standard AC welder. There are two schools of thought concerning welding cast iron. Those who preheat and those who don't. You can check out the Lincoln Electric website for more info on both methods. The method I use is the non preheating method which has been great for me. Go to Tractor Supply or anyone else who sells machineable cast iron welding rod. Here are the directions off of the machinable cast iron rod I use. 1. Prepare area by grinding. 2. Preheat not necessary but warming to 400 degrees is desirable. 3. Use medium arc length, stringer, or narrow weave beads. 4. Run short beads, fill crater when breaking arc and peen deposit immediately to relieve stress. 5. Chip slag after each pass, re-strike arc on deposited weld metal. Cool slowly. AMPERAGE RANGE: (3/32) 40-80, (1/8) 70-110, (5/32) 100-140
Once again, I've had great success in my metal shop using the non preheat method. If you want you can then go over the weld with JB weld for cosmetic and sealing purposes. Good luck.

 

[Anonymous-0]

Been several years since I did much brazing, however I used to do a lot of it, and since I did it several times a week in my line of work I got fairly good at it, and was much better at brazing than welding. I once had a broken exhaust manifold that litterally cracked at the point just above where the pipe connected to the manifold (small block chevy). At the time I was both too cheap to buy another, as well as money being tight to boot, and since I could bring it to work and braze basically free of charge I decided to give it a try - nothing to lose but my time. Took a much larger torch tip, and lots of preheating then lots of flux, but it brazed up nicely and held until I sold the truck. Your block would require a LOT of heat to even think of getting it to flow as it has much more mass than the manifold I did. Same principle with silver solder - takes less heat, but basic priciple is that the cast would have to be at the temp to melt the filler material, and cleaned, fluxed. Keep in mind that the block (basically the whole tractor) is acting as a heat sink, thus would absorb a lot of heat before finally getting up to that point. Cast can be brazed and welded successfully contrary to what many say, but it takes a little experience and patience to do it correctly. Clean with a lot of heat on large items such as this.

 

[souNdguy]

Anyone used silicon bronze for welding cast?

soundguy

 

[Bob Harvey]

Many moons ago, I was a quite good rare metals welder (heli-arc - now argon)and was capable of welding paper match folder thick aluminum alloys (worked in a Formula 'A' class race car shop), it seems to me there was an arc welding rod called Ni-Rod which was a nickle compound and designed for cast welding, preheat was a must. Hope this helps.

 

[Dan]

Also - doe the stop holes drilled at the very ends of the crack need to go all the way through - or just halfway or so?

 

[Dan]

Bob - unfortunately the engine is fully rebuilt and on the tractor. This is why I was hoping to silver solder it or some other low heat "weld". The 9N does not have a high pressure water cooling system, so it only has to withstand about 3 psi or so. I was hoping to fix this with a metal filler so it would expand whith the block as it heats.

Dan

 

[Bob Harvey]

Hey Dan, there HAS to be some form of epoxy product that will 'Pelican'..............fill the bill !!

 

[trucker40]

I think you would be better off using a welding rod in an arc welder than trying to solder it.Just my opinion.I would use 7018 rod,heat the area around the crack after I veed it out and drilled the ends of the crack.I wouldnt drill all the way through either.I would weld about an inch or less,let the glow die,peen with a chipping hammer(peen means take the pointed end of the chipping hammer and hit the surface of the weld and the area right next to the weld)to reduce stress on the weld,then another inch.You want the metal say 400 degrees,hot enough you dont want to touch it but not glowing and also you want to hit it with a wire brush before and after you weld to get all the slag you can.Once you get the whole crack welded,I would hit the top with a grinder real quick and maybe heat it a little with a torch maybe.What you want to do is weld your little short welds but you want them all the way to the surface,so actually you are building them out from the bottom of your V to the top of the V.You dont want to put another pass on it if you dont have to.I think if I had it close to the surface I would fill the top up with JB Weld.What you are doing is welding it,on the low side of the heat range for the rod,trying not to shock it and crack it,so thats why you preheat it a little,and trying to be done in one pass.I would try and find a piece of cast iron and practice first because it can and will crack.Thats what I would do,but I have not welded a motor block before,I welded a hydraulic pump,a Axle housing,a differential housing,drive wheel on a D6 Cat,600 Ford exhaust manifold,but no block.I have seen people weld on a head with 6011 and it worked,but I would rather use 7018.

 

[Dunk]

There might be some "glass" type of repair stuff that would work.

Brazing on the block would require a considerable amount of heat as quick as the cast block would absorb it.

 

[Den N Ms]

Dan ,You should have used lock n stitch.But now that you have it veed out,you might try JB weld quick set.I used some a couple weeks ago to radius the insides of a aluminum sheet metal intake manifold I made for my sons race car and I liked it better than the regular JB Weld.It looks darker I think it may be stronger.It also stays in place better,not as runny so it wouldn't run down off your block as easy.I would clean up the crack with a stainless wire brush(size of a tooth brush) and heat the area with a propane torch while brushing to remove oils,anti,moisture and old JB from the pores of the cast.Not use any brake cleaner on it.Mix up the JB and fill the crack using a cut down plastic spreader,rubbing it in the crack a little at a time going both ways to fill pores and the crack up.then put some more over the top.It sets up in 10-15 minutes.Or try and weld it like mjank said with a nickel,cast welding rod short welds and peen it a lot and cool it slowly with a propane torch.I have used a Mig welder many times to weld cast iron N engine blocks and cast iron castings with good success,using the same short weld peen method.You would have to get the block to hot to braze it with out preheating .

 

[schultp]

Dan, why don't you email the Lock and Stitch company with pics of your V'd out crack and see if they still think you could repair with metal stitching. It seems this method is the best for your application. It seems like you are getting a lot of differring opinions from several folks that have welding/brazing/soldering experience. You have invested a lot of time and effort into this tractor. It would be ashame to take the wrong approach and end up with more cracks.

Take a step back and carefully evaluate your options.

Just the opinion of someone with no metal repair experience.

Good luck.

Paul.

 

[schultp]

Dan,

One more thought. Check out the www.por15.com website. They have some epoxy putty and/or por15 in a tube that might be other alternatives.

Paul.

 

[Dan]

I tried the galss type sealer you pour in the radiator - twice. No luck. Also tried good old Bars leak - no luck. Finally, I decided to clean everything out of the crack and re-evaluate.

 

[Dan]

I originally wanted to go with the Lock-n-Stitch method - but the crack goes along the backside of the block, around the corner, and up to the #4 exhaust port. Here is a pic of the crack after I got it back from the machine shop. Because of the corner - I couldn't use the stitching method - that is why I tried the epoxy route.

To me - it would seem that metal filler would be the best option as this part of the block heats up so quickly on startup due to the exhaust port and stresses that crack. But - maybe I just did not get this area cleaned or prepped right last time(?)

Thanks,
Dan

 

[Dan]

I like the idea of using the quicker setting JB Weld - the long cure stuff sure does flow when applied - and this crack is on a vertical surface. Thanks for the tip on prepping the area - I have not done this before but it makes sense. Any idea on how to rough up the cast surface for better adhearance without really taking more material off?

Dan

 

[Dan]

Wow - that is some great info. Much appreciated Trucker. Sounds like you have quite a bit of welding experience. I start my beginning welding class tonight at the local night school, so I will soon understand those techniques I hope.

Dan

 

[Dan]

Sounds like I don't have enough heat on the cast - drats. I tried my oxy/mapp torch Sean gave me and really heated the area up well - but the solder would not flow from the heat of the block by itself. Looks like I am stuck with some form of epoxy for this fix as I don't want to tear the engine back down now.

Thanks,
Dan

 

[Dan]

Good info - thanks! I will run this by my instructor tonight - my first welding class starts tonight at the local night school. I have always wanted to learn to weld - so I decided to bite the bullet and take some classes.

Dan

 

[souNdguy]

Yep.. if the solder didn't flow.. not enough heat.

The map torch will produce it.. just take a while.. and the block would have to be dry too.

Try that alumalloy rod.. i believe they may melt a lil lower temp than silver solder.. lots of flux.. and acid flux paste.. and if you can find it.. tinning paste.. which is kind of a flux paste with ground up solder in it.. so it tins as the flux heats up and the solder melts.. I've seen radiator shops use it..

soundguy