Cracked Block temp fix? (somewhat urgent)

[printjunky]

OK, I was losing coolant and thought it was a freeze plug. Pulled the wing (Took no time ... huge thanks to PO Mike Laudenstein from Menomonie, WI for using almost 100% stainless hardware!) and it appears I have a cracked block. Just below the freeze plugs, running front to back from the second freeze plug to the other side of the third plug. It looks pretty tight (takes a half hour or so to empty the radiator).

The big problem is I'm working shade-tree style (I have no garage). I was lucky enough to get a sunny 50-degree break today so it's great weather to work out there. But early winter returns Tuesday with highs in the mid-30s the rest of the week.

Does anyone have any insight into some kind of temp fix that might work to plug this leak, preferably to get me through the winter? Otherwise, at least slow it enough until I can figure out a place to get a little deeper into it.

Thanks,
Shawn

[printjunky]

Reading a lot of anecdotes about JB weld in similar context ... unstressed water jacket, tight crack. Something called Belzona looks even more effective (amazing, really - a manufacturer approved repair for some diesel internals!?), but not sure I can get that anywhere local (and rumor is it costs a LOT).

Off to the store.

[Mercedesrover]

Google "locknstitch". They make pins for such a repair. Drill and tap the crack and thread these pins in. Basically a nicer way of the way we used to fix cracks in the day where we would drill a hole in the crack, drive a pin in, then drill another hole right next to it and drive another pin in, continuing down the line until you filled the whole crack.

[Terrys]

There are guys who weld cast iron using a jazz box, like a Tig, with great success.
I had a cracked block in an old Furguson tractor that sounds just like what you're describing. I took a die grinder, V'd the entire length, and JB'd it, and it's still going fine 25 years later, albeit with someone else.

[printjunky]

I have great access to the crack, even without pulling the manifolds, got it nicely cleaned up and down to metal with the dremel (bonus, stuck a hose in the freeze plug hole and cleaned out a TON of gunk from that water jacket), drying it out now with a heat gun, then mix up some JB Weld and get that started curing.

I've heard of pinning and of course welding/oven welding for cast, but I need to try something in the next 24 hours, or it's probably going to have to sit for the winter. After just 3 weeks back on the road!

The crack is obviously the result of water left in the engine while being stored. Likely by me last winter after doing some leak checking in the fall. It did occur to me when freezes hit last winter. I knew I had water in it at one point and thought I had it all out (see clogged petcock above) but apprently not. Should've listened to my gut and run some antifreeze through it just in case.

[Terrys]

Thinking about it, I remember being advised to get the block warmed up before puting on the goop. Even with the system drained, I wouldn't be afraid of letting it run 2-3 minutes at idle. I also remember degreasing the whole are and letting the JB fair out to about 3-4 times the dimension of the ground crack.

[SafeAirOne]

Probably too late now, but can't cast iron be brazed? Especially in a low-pressure system like this? Especially since it's only a temporary fix?

Hopefully it only cracked there on the outside of the block and not internally too.

[printjunky]

Got the crack covered in a layer on JB Weld last night (worked in the driveway until 2am!) and got the wing and starter all buttoned back up before tomorrow's upcoming cold snap.

Everything went well, I suppose. I'm worried I don't have a thick enough layer - not because I wanted to slather it on there, but I had a little bit of limited visibility around the exhaust, and there is an off chance of a void in the wrong place (on or too near the crack). Pretty sure I got it all covered, but I had warmed the block with a heat gun for awhile beforehand, and as soon as I applied the JBW it thinned quite a bit and ran, so I kept re-spreading it until it firmed up. Moving it around resulted in a thinner layer than I was originally shooting for. I would only recommend the heating process for repairs being done from above with the advantage of gravity. Also, I never could get the crack perfectly dry. Even with the water jacket bone dry, I'd still get the tiniest, microscopic capillary action bringing water to the surface of the crack. VERY small, barely perceptible amount (read as a tiny darker line that made tiny bubbles when I put a torch on it (- still didn't go away though)) except in one spot (which produced maybe two full drops total). The tiny line really doesn't worry me, but after about an hour, when the JBW was the consistency of putty, I used a wet finger to smooth the JBW over where the drops had originated. That area was dry at that point, but the fact that drops made it out through the uncured JBW, could indicate a possible future exit route.

It's 25 hours curing right now, but it's been right around 50 most of that time, so I'm going to wait until after work tomorrow to fill it up and test it out. Here's hoping I can put off Plan B until Spring. Maybe even late summer when I can consider Rovering to my family's annual Cape Cod vacation, where I'm much more likely to find a block than here in the middle of the country.

[printjunky]

Well, tested it out this morning, and I can't tell if it's leaking because I'm getting NO coolant circulation!!! It's overheating in about 10 minutes and I'm not getting ANY heat. Anyone have any idea why that might be the case? NO way anything got in through the crack I repaired to stop the flow. It was hairline. If anything, I should be getting better circulation after flushing a ton of gunk out of it. And I didn't touch anything else cooling-system-wise.

I did some work in a buddy's rad shop back in NH in the 90s. So I've done recores, power backflushes, etc. So I have a little insight here. But I still don't get it.

The only things I can figure:

Water pump not pushing for some reason (no apparent leaks or noise, etc).

Thermostat not opening (even though it worked fine Last week).

or a clog somewhere (again, even though I had good circulation last week).

[SafeAirOne]

Air in the system (especially in the pump).

EDIT: ...or whatever coolant you could fit in has now circulated through the system and made room for the remaining gallon of coolant to fit.

[printjunky]

Ding, ding ding! We can change it from Occam's Razor, to Mark's Razor. Simplest and least alarming of all possibilities. Air bubble. I don't know why (esp. with my experience) I didn't catch that immediately when only about 7/8 of a gallon went in the first time. (after my little panic) Ran it a bit with the cap off, and it took another gallon or so.

So it's running like a top now. The next day (after resolving the coolant issue) it acted super cold-hearted, in fact I'd say it was not firing on all 4 cylinders. Swapped the plugs (still getting pretty bad carbon fouling) and after some hesitation, it's running better than ever. Got it on the highway for the first time last night, and pretty handily got up to 55 or so (speedo not hooked up) with a little room on downhills yet. Steering was smooth, noise was not insane, nothing alarming.

And so far, it appears the JB Weld repair to the crack in the block is holding fine. Haven't checked the coolant level since the run last night, but it's blowing good heat and running at around 150.

[SafeAirOne]

My diagnosis was based on experience--I almost ruined a brand spanking new water pump once a long time ago; I forgot to take the gallon jug of coolant with me on the drive around the block following the pump installation. It doesn't take long for the needle to peg and the pump to run dry with the system filled to half-cpacity.