My Cub is toast

[flusher]

Bought this 1948 Cub last year.



Not running but looking pretty good as it sat. Cleaned it up. Low compression. Pulled the head and reseated the valves. Brought the compression up to 60 psi range (still way too low, should be 100 psi +).

Pulled the engine and took it to the engine shop in tall stack configuration for a complete engine rebuild.



The engine guy stripped it down and was hoisting it over to his cleaning tank when this happened. The darn flange on the lower front side snapped off the block before the block had hardly lifted off the bench. The front end bolster gets bolted to the tractor via this flange which also carries the governor.
So it's a pretty important piece of the main support structure for the tractor.



Looks like a previous owner cracked it and tried a hillbilly fix using JB Weld. That sure didn't work-- the crack propagated until all that was holding the cracked piece in place was the timing cover.

So now I have parts tractor and have to find another Cub, this time one that's running. What's discouraging is that neither I or my engine guy spotted this crack until it was too late. Bummer. Because that makes it more difficult to spot this problem on Cubs that I'll be looking at in the future.

It turns out that this failure is a well know deficiency in the Cub design--just not enough meat on the engine block casting in this area. Some unlucky Cub owners have snapped it off by hitting a pothole at high speed. Generally it will crack in this area and just cause a nagging oil leak at the front of the engine. But sometimes it cracks off the block completely like this one.

I don't think welding is an option here. Welds on cast iron parts are notorious for being hard to do, are prone to post-weld cracking which would be aggrevated in this case because that busted flange carries a lot of the tractor weight and is in a high stress area.

I need to find a couple of large wooden crates to store these Cub parts and move on to my next vintage tractor adventure .

 

[Soundguy]

here's my guess. ( I own a cub too )

I'm gonna give the prev owner a lil credit and 'guess' that he didn't know the extent of the real damage, and had one of those mentioned 'oil leaks' you spoke of, and did the jb weld 'fix' on it, not as a structural fix.. but to stem a leak. poor guy may not have known of the cracked webbing.

Here are yer options as I see em.

1, get a spare block.

2, get another project cub in better shape? and use the old one as parts.

3, get another project cub to canibalize for parts for this one.

4, not reccomended. repair it.

if I was flat but broke and lived in nowherville and had a lil vegi farm I worked on to eat. I'd clean that crack, drill it out for some repair studs and do a lil threaded stitch work for stability, then I'd get a propane weed burner tip on a bbq grill tank and have a buddy help me preheat the crack.. then I'd get some cast iron spec'd welding rods. and do a 1" stitch at a time. then use a welding hammer to peen the bead and sourounding areas to relieve stress, and keep the preheat going.. weld a lil more.. keep heating and peening till done. then Id keep the preheat going, perhaps by setting it on my gass grill set to 450.. (1st choice )or burrying in white play sand and preheating it while burrying it, and let it slow cool.

I havn't done any engine blocks.. but have done some cast brackets for loaders that way.. weight bearing parts.. and have had great results.

again.. the reapir would be a last ditch desperation move. or if I just needed a hobby tractor to play with.. etc.

soundguy

 

[whodat526]

1, get a spare block.


soundguy

this is what i would do because there is thousands of cubs around being parted out

 

[Soundguy]

yep.. no shortage of parts there..

 

[flusher]

I've been searching for another block on the Web. Found a few locally (in Woodland CA north of Sacramento) and, of course, on eBay. Nothing so far on craigslist. My tractor club meets first Monday of each month. I'll see what the guys say the week after next. Maybe I'll luck out a make a deal for a block. If so, my first stop will be at the engine shop in Red Bluff for dye penetrant and Magnaflux inspections on the block in that vulnerable area.

On the other hand, if a running Cub shows up for sale around here, I'll be looking that way also.

Wish me luck.

 

[DJ54]

Too bad you aren't a little closer. I do believe a buddy of mine has a good used engine, and a NOS block he picked up somewhere in his horse trading deals.

 

[flusher]

Too bad you aren't a little closer. I do believe a buddy of mine has a good used engine, and a NOS block he picked up somewhere in his horse trading deals.

Thanks for the input.
I'm heading for the weld shop today to talk about repairing the block. It a big shop that does a lot of repair work on the big tractors used around here in the rice fields and hayfields. My guess is that their customers regularly bust cast iron parts that need welding repairs. We'll see.

 

[Soundguy]

that's a bad break.. don't be surprised if they pass on it.

if it was my machine and in my shop.. I'd try it, knowing I started with a junk block and couldn't get any worse..

 

[flusher]

that's a bad break.. don't be surprised if they pass on it.

if it was my machine and in my shop.. I'd try it, knowing I started with a junk block and couldn't get any worse..

Yep--talked to welders at two shops that I've dealt with previously. They both said to forget it--they couldn't guarantee their work because of the location of the break.

I'll find another block and continue from there. Meanwhile, I'll get some Lincoln Ferroweld rod and see if I can learn to weld cast iron. I'll start with come CI scrap lying around my shop before torturing that poor, busted Cub block.

 

[Soundguy]

preheat.. use propane .. it's cheap.

consider stitch / dowling the repair first if you can.. they will help prevent distortion too, also if you can bolt the flange to a jig to keep it true instead of drawing like it will want too.

slow cool.. peen to reduce stress...