Broken Crank!

[woodiewagon46]

I don't know how many of you guy's are members of the V-8 Ford Club but I just read an article about a 1950 Ford that had a broken crankshaft and the car still ran. The break was very close to a bearing so it helped keep it together but it was a clean break, amazing!

[Tim Ayers]

Wow, neat. There's been a couple of members on here that had similar stories. One guy had the crank and cap break and the car ran. The only reason the dude knew there was an issue was the engine made a weird vibration.

[DD931]

When I was in high school in '57 a friend had a '52 Customline that was very tired but seemed to run OK. Drove us to school every day. We were coming home one day and heard a strange crunching noise as the car coasted to a stop. We had no idea what had happened, of course. The engine would crank (or at least the back half did), so we kept trying. You can guess the problem we ultimately diagnosed - broken crank. Straight to the junk yard!! The only time I've ever heard of/seen a flathead crank break!

[deuce_roadster]

Seems odd that if the back half still worked, the timing gears wouldn't be going around and the cam wouldn't be turning and if the only the front half worked the flywheel wouldn't be turning to move the car. A mystery. For the car that still drove anyway.

[V8COOPMAN]

Originally Posted by deuce_roadster

seems odd that if the back half still worked, the timing gears wouldn't be going around and the cam wouldn't be turning and if the only the front half worked the flywheel wouldn't be turning to move the car. A mystery. For the car that still drove anyway.

exactly! dd

[Greg58]

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This is not that uncommon, my brother broke two crankshafts when we were young hotroders. Both were small block chevys, both still ran. The crank broke across the front main journal on both, the indictor was harmonic balancer wobbling and timing chain slap. He was luck as neither suffered block damage.

[estout81]

Years ago a friend of mine bought a '63 Chevy with a 409 that made a weird noise in the engine. Nobody could diagnose the problem. He got it cheap. Broken crank and it still ran!

[Newc]

Hi all; Sold a merc crank.. buyer mag'd it and it was cracked! Local machine shop that does flat heads has a broken crank door stop. It pays to mag the crank if possible. Newc

[Jack E/NJ]

In all these "still ran" cases, the crank break may have been clean but also a jagged one. Seems logical that they still ran with some additional vibration as long as the jagged ends were kept close enough together to *mesh*. Jack E/NJ

[deucemac]

I was a GM service manager in the late '70s to early '80's. At that time GM decided to put cast crankshafts in the 1 ton trucks and vans. They would come in running well but have this weird "clucking" noise. When we heard the noise we would grab the balancer and push and pull on it and sure enough there was lots of play. Sometimes they would toss aĺl the belts which was another dead giveaway. We would just install a new motor and on their way they went. We pulled some down and all had broken crankshaft between the front main and the first throw. The break would be at such an angle that it would drive the short nose piece and still run. I took one home and after a ring and valve job and crank kit, put it in my dad's 1968 El Camino when his old 307 died. When he passed away, I got the car and drove it for about 800 miles and then did a real rebuild on it. It finally breathed its last at about 260k and in went another rebuilt. My son now drives the car with a total of a little over 500k on it. Had GM not gotten cheap and used cast cranks in 1 tons instead of steel cranks, we in the service departments would have lost lots of work and my dad might have had to buy an engine with his own money. But again, they would run but have a weird and distinct clucking noise. So , yes engines can continue to run with broken crankshafts.

[Mart]

My Scottish friend Gordon Brennan had a broken crank in his 35 cabriolet. It was a French crank and continued to run for a while.

Mart.

[Tim Ayers]

Originally Posted by Jack E/NJ

In all these "still ran" cases, the crank break may have been clean but also a jagged one. Seems logical that they still ran with some additional vibration as long as the jagged ends were kept close enough together to *mesh*. Jack E/NJ

That's what I was thinking too. Almost like teeth. Some of the snarky comments were a tad out of line. Stranger stuff than that has happened.

If I recall, that's what happened to the crank in the one post on here a few month's back.

[JM 35 Sedan]

Originally Posted by Jack E/NJ

In all these "still ran" cases, the crank break may have been clean but also a jagged one. Seems logical that they still ran with some additional vibration as long as the jagged ends were kept close enough together to *mesh*. Jack E/NJ

Originally Posted by Tim Ayers

That's what I was thinking too. Almost like teeth. Some of the snarky comments were a tad out of line. Stranger stuff than that has happened.
If I recall, that's what happened to the crank of that one post that was on here a months back.

This is exactly what I recall recently reading about on a thread posted either here, or on another forum. I believe the crankshsft fractured in half under the center main bearing in a "jagged" configuration, and the engine still ran but vibrated during acceleration. There were pictures of this posted in the thread.

[V12Bill]

In the post referred to, wasn't the cause of the crank break, because when the crank was reground, there was no chamfer on the mains? There is a cause for the GM crankshafts breaking, is there a known cause for breaking flat head cranks other than trying to see if they will turn 9,000 RPM?

[Tim Ayers]

Originally Posted by Mart

My Scottish friend Gordon Brennan had a broken crank in his 35 cabriolet. It was a French crank and continued to run for a while.

Mart.

Hi Mart:

This was the thread I was thinking of.

[Mart]

I found Gordon's thread:
http://www.fordbarn.com/forum/showthread.php?t=206095

Mart.