Author Topic: crack in 6/1 head  (Read 365 times)

Mtour

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crack in 6/1 head
« on: October 19, 2021, 11:42:31 AM »
Hi all

 My new to me 6/1 has a crack in the head water jacket, not sure how to go about fixing this. It would be great if a bit of jb weld would stop the leak, but my thought are to take the head to a machine shop and see what can be done.

Any thoughts..thanks

mike90045

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Re: crack in 6/1 head
« Reply #1 on: October 20, 2021, 05:39:36 AM »
i see the crack in the exterior.  Does the crack bridge anything internally, like to the crankcase ?

You could grind a V into in, along the length and try epoxy on the fresh bare metal, but many epoxies weaken at 200F, where you want to have the head running.  add the inevitable oil, maybe some weld may hold, if you can get a cast iron weld artist

mobile_bob

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Re: crack in 6/1 head
« Reply #2 on: October 20, 2021, 11:40:48 AM »
cast iron welding is not particularly difficult, it just takes some patience and prep

as mike stated, V notch the crack well, drill a small hole at each end of the crack
preheating in a bbq grille doesn't hurt either

your local farm store or welding supply shop has what they refer to as cast iron rod for stick arc welding, i prefer a nickel rod myself

the trick is to weld short stitches, maybe a half inch at a time, then quickly using your chipping hammer pien the living crap out of the weld, i use the chisel end of the hammer and run the chisel perpendicular to the crack, and i hit it moderately hard, and maybe 50 times per stitch.  the goal is to expand the weld a bit so it doesn't have time to shrink and pull a crack open.  then stitch the next section, wash/rinse/repeat until done.

sometimes there will be grease/oil or other crap polluting the weld, so don't worry how it looks on the first pass.  just do your best, then grind it back down into a V and reweld it, the second time it will weld up nicely... just remember to pein( or is it pene, pien?) well after each stitch.  when you are done you can grind the weld flush and it will not look the worse for wear and it will work.  if you have a pin hole seep afterwards, just add a little water glass to seal that up and you will be good.

i assume the crack was caused by frost/freeze damage, if so generally this type of crack will not result in a structural problem.

over many years i welded crack castings of all sorts, from cylinder heads, and blocks to 60k lb tulsa winch cases, and countless gear cases.  its not difficult to do, just take your time and remember to stress relieve ever stitch immediately after welding it, with the hammer,  work it over well and bob's your uncle.

wait, i am bob!

bob g

ps. i finally was able to see the picture, and am concerned about the crack running out into the core plug pocket, that will be a much more difficult crack to weld to the end because it ends in the core pocket.  in this case, i would drill an eighth inch hole at the other end of the crack, remove the core plug, and weld up as best i could, then with a dremel tool and a carbide burr re-establish the core plug pocket and install a new one with some sealant, then i would use the water glass for sure.  an off the shelf product that works is K&W block seal, it comes in a copper colored can.  follow the directions on the can and it will seal off any remaining issues. 

cracks that run into core plug pockets are particularly difficult to work with, but well worth the effort.
« Last Edit: October 20, 2021, 11:49:11 AM by mobile_bob »
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Mtour

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Re: crack in 6/1 head
« Reply #3 on: October 20, 2021, 10:48:42 PM »
Thanks for the replies,

 I went with the JB weld repair, the crack after further inspection runs from one side wall to the plug and continues, on the other side of the plug to the side wall. I used a small paint brush and cut the bristles back to make it stiff, then used it with brake cleaner and compressed air to scrub the cast iron clean. With the brush I was able to scrub the JB weld in and down the length of the crack. Head is running 190f-205f, JB weld is rated to 500f. The engine has been run for 8hrs under load so far and the repair is holding.

 This is not a ideal fix, but the crack running into the plug made the repair with welding look expensive to have a machine shop repair.








 

« Last Edit: October 20, 2021, 11:04:10 PM by Mtour »

cujet

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Re: crack in 6/1 head
« Reply #4 on: October 21, 2021, 12:22:15 AM »
I used my TIG welder and 308 stainless rod to successfully weld up a fully broken Listeroid starter motor bracket. Cast, I'm sure, from the very same high quality alloy as the rest of the engine...  Not only was it incredibly easy, it's held up for years. I've even over-stressed it by cranking the engine without the compression release engaged. No issues.

Just guessing here, but I have a feeling the cast iron they use contains materials from recycled Dodge Ram's, Crown Vic's and obsolete container ships. I think India does recycle about 20-30% of the worlds ships.
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mobile_bob

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Re: crack in 6/1 head
« Reply #5 on: October 21, 2021, 01:00:46 AM »
get some waterglass  and have it ready, you will need it sooner than later.

the k&w blockseal is amazing stuff

the first time i used it was on an old endt 71 mack 6cylinder diesel that had a crack just under the deck that ran nearly 14 inches in length, and the water ran out like niagra falls
(only a slight exaggeration)

in desperation i was told to use a can of this stuff, follow the directions to the letter and see what happens

the crack sealed off in about 5 minutes of run time, did the drain/dry/flush and refill with antifreeze mix and it never leaked again.  a few months later i tried it on a crack down the center of the airbox on an 8v71 under the blower,  it sealed that one up too, and reportedly never leaked again.

now both of those were freeze cracks, as opposed to stress cracks, so maybe a crack that has movement will open back up again.

cujet makes an excellent point, it might be, and likely is the case that the recycled materials the indians use to cast with turns out to be more closely related to cast steel than grey cast iron? if so it will weld very easily and machine just like any other cast steel products

about 25 years ago i was researching having a lathe bed casting poured by atlas foundry in tacoma wa.  i was asked what i wanted it made out of, and i asked for grey iron.  i was told they don't do much of that anymore, "everyone wants cast steel"  i asked why...

"because of the ease of repair welding down the road, no one wants to fuss with grey cast iron"

cast steel welds as easily as mild steel in my opinion, and does not require a lot of special prep, preheat (in most cases) or special rod, that is a huge bonus as stated it welds easily and the weld machines just like mild steel.

if it turns out that the crack opens back up, i would recommend having the head welded, unless the crack runs down somewhere making access with the filler rod impossible to get a good weld.

have you, or can you determine the cause of the crack? 

bob g
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MachineNLectricMan

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Re: crack in 6/1 head
« Reply #6 on: October 30, 2021, 11:20:32 PM »
I'll tell you how we use to repair thousands of cast iron bearing and gearbox casings back in the old oilfield days. Simply grind the crack out and run brass into the crack. You have to make sure you grind all of the crack out or it will continue to grow after it is repaired. It takes some skill to run the brass into the crack with an Oxy Acet. torch but when you get the hang of it (like judge Roy Bean) it is fairly easy. Brass is somewhat soft and will tolerate more shock and abuse and is great for water jackets and things that vibrate a lot.  For stronger repairs in bearings I used nickel based spray metal, which takes a lot of skill and experience to apply correctly but will reliably repair the nastiest cast iron. There are many varieties available for different purposes, some are machinable. Brass is also the best way to repair fuel tanks.

All of the good welding rods for cast iron were taken off the market decades ago, I once used them. The stuff they have now days is pure crap.

JB weld and the likes are intended for emergency temporary repairs only.

If I had my old equipment up and running I could do this work, but that may be another year or so.


cujet

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Re: crack in 6/1 head
« Reply #7 on: November 15, 2021, 02:34:58 PM »
I'll tell you how we use to repair thousands of cast iron bearing and gearbox casings back in the old oilfield days. Simply grind the crack out and run brass into the crack. 



That too! Brazing cast iron is a very good way to repair it. One little trick that helps is to incorporate a piece of regular steel in the repair, as this significantly helps the brazing job quality.
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