Got it torn apart and found this mess.
It looks like the rear main web broke out first causing the crank to break.
There are some shiny areas on the fractured cast iron so it must have been moving around before it completely broke.
The last 50 to 100 miles it had some funny noises and vibrations...more than usual.
I'll have her running again in no time. (If you believe that I'll sell you a bridge)
It just takes me longer now than it did 50 years ago!
There is a cast iron welder in Washington nick named "Cast Iron Mike" that can weld the rear web back in your block. I have a REO cylinder that was badly broken up and he did a fantastic job weld repairing the cylinder. I also have a 16 T block that has the rear web welded back in place. A friend where I live has a 12 block that has the rear web brazed back in place. I can find Cast Iron Mike's phone no. if you are interested.
If you have another good block that is correct for your car....then it may be less costly to just replace the block. Time to put in a Scat crank.
Bob, broken cranks rip the rear wall out of the block. Blocks in my experience do not fail and break cranks.
Unless a block is real early, say 1914 or so, another one can be had for less than it would cost to repair yours. Don't spend a bunch of money on a block that is not valuable enough to repair. And don't worry about the serial number, that can be dealt with.
Allan Richard Bennett in Australia asked me to inspect the break area of the block for evidence of the broken surfaces working against each other.
It's obvious these have done that.
The breaks have worn sorta smooth and very shiny on the sides and there's a clean break across the top.
It's a '23 block and I have a few spares so it's a wall hanger or anchor.
Cast Iron Mike welded up a Rajo head for a friend and does great work but this block is not a candidate for him.
Hi Bob, thanks for checking the damage for me. Yours is the third mid 20's block I know of to have broken out the rear main web and taken the crank with it. I have almost made it mandatory that my customers allow for crack testing of blocks before spending any money on re-boring, bearings etc.
It is cheap insurance.
Eric, you may be right at times. However, enough broken blocks show evidence of cracking before breaking, that I am confident that in quite a number of occasions, those cracked blocks break, taking the crank with them. At first I thought it was only the early blocks, but others are turning up. It would be interesting to know what causes the cracking in the first place.
Allan from down under.
I forgot to mention one possible cause for these breakouts. The land which is milled to accept the nuts on the rear main bearing bolts is machined with a sharp angle to the block, creating a perfect stress riser. Two of the blocks I have inspected have started cracking sideways from this machining. Perhaps a generous radius at this point would have helped.
Your opinions please.
Allan from down under.
Were there any beach marks on the crank where it failed?
I see where people want to use JB Weld to fix all kinds of things.
Will it work in this case?
sorry about your block and crank
Bob,I have doubt's about the block breaking first. What type 4'th main were you using and what shape is it in?? Bud.PS,Even if the block could be welded perfect for 37 cents it will still be sprung!! Bud.
I wonder if the engine came from a car that was hit from the rear. The solid drive shaft housing drives everything forward. The rear main takes the force. It may have been cracked for a long time. Unless the block was fluxed, it may not have shown up on a rebuild.
There are no obvious flaws in the crank.
The sharp corner by the bolts was the last part to break.
I bought this short block as a rebuilt engine about two years ago.
The fourth main was rebabbitted and on assembly it slipped freely onto the output shaft and didn't bind on the pan.
JB Weld, huh? Maybe I'll try that.
I wonder how many broken cranks didn't have aux trannies hanging on the back?
No aux trans.
Bob and Allan,
Your point is well taken. It's hard to tell which failure caused the other. I always magnaflux the main bearing webs in the block, and will do so more carefully from this point. I also mag the cranks, of course. My assertion that breaking cranks destroy blocks comes from my experience in finding a high percentage of cranks that I have magged are cracked, whereas very few blocks are cracked in the main webs. Of these, most are early blocks.
It's hard to argue with your magging results.
Seems like a lot of us have been through this...maybe we can get some more input.
Condolences on your mishap. I am a two event member of the club. Both were engines built long before I knew what magnaflux was, much less had one. It make quite a memorable sound, doesn't it?
I have blocks and cranks if you need them. Unless your block is a real early valuable one, just find another, it's not worth repairing,
It looks like your engine had no mag ring installed. I wonder if the natural frequency at the rear of the engine block was changed enough without the mag rings mass to cause a vibration at certain frequencies. The rear of the block forms a diaphragm, so it is a possible scenario, at least in my feeble mind.
I'll never forget the noise...I'll hear it in my sleep!
My wife was behind me in our '40 Ford PU and the noise scared the heck out of her.
This was a '23 block so it's easily replaceable.
I'm going to put the old engine back in after a little work.
Don't know about the missing mag ring...something more to think about.
What kind of a hair-brained theory is that? (WAIT, don't get mad at me yet) It sounds like something I would have said. In all seriousness, I have worked with waveform phenomenon quite a bit. Mostly at RF (radio frequencies), but also higher (audio and mechanical) frequencies. By the way, did you know that Earthquake damage zones conform to a waveform phenomenon pattern?
I would love to tell you a story, as told to me by a co-worker some years ago. But I cannot tell it here (sworn to not go public). It involves a mechanical frequency vibration on something a lot more solid than a model T engine block.
My condolences on the block, and a belated welcome to the world of model Ts! Thank you for the update.
A good friend some years ago had a model T that broke the crankshaft (I think) three times before he discovered a crack in (I think it was) the center main webbing. It had apparently allowed the crank to flex enough to break, but not yet broken out itself.
J B Weld itself may not hold. But I have seen blocks and bearings bolted back together with steel pieces bridging the breaks.
Good chance you nailed it.
Drive carefully, and enjoy, W2
Wayne, I used to work for a large electric motor company and had serious problems with a certain design. The end plates were fabricated from 2' steel plate and in use would fail and tear the plates in a rough circle around the bearings.
We brought one of the motors into the lab and ran some static tests on it...(Hit it with a big hammer, and measured the critical frequency of the motor frame assembly). Turns out its critical frequency was within a few hertz of it's running frequency.
For test purposes, the lab guys bolted a few steel blocks onto the end plate which moved it's critical above it's running frequency and the problem was solved. So yes it does happen!
Probably not on Model T blocks though.
Don't be afraid to weld the block. If you can find a good welder to do it. Last summer I helped a friend repair an engine which had lost babbit in the 4th rod. The babbit hit the magneto ring and cut the windings. We found that someone previously had welded the rear main web. We had the crank ground and poured new bearings in the block and rods and reassembled everything including a new mag ring. I have no idea how long the engine had run before we had it out as it was in the car when my friend bought it. After we worked on it, it ran like a new engine and so far (a year later) has had no trouble with it.
John, that reminds me of a title to an article I saw years ago, "Electric motors don't fail electrically."
Ralph, That's an accurate statement. But the mechanical failures sure kept our repair shop busy!
I vaguely remember reading a story about the Model T transmission. Customers were complaining about the noise the gearbox was making. Henry was using the best gear manufacturing equipment available at the time so there was no way to improve the quality of the gears. The solution was to change the natural frequency of the components so the harsh sound was around middle C and sounded "in tune". Customers stopped complaining about the gearbox after that.
I don't remember if it was in a Model T book or a gear design book. Has anyone come across that story?