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vugbug68 Samba Member
Joined: June 25, 2006 Posts: 2696 Location: sacramento
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Posted: Sat Nov 21, 2015 11:36 am Post subject: Broken crank |
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My friends engine that had the crank snap in two. It is a forged German crank so I'm sorta puzzled as to why it broke, but then again I did find the GEX stamp so that might be the answer. It lasted 1 year of daily driving (in my friends car) then just broke. Pistons, cylinders, and heads were all in good shape.
_________________ 71 Super - Backroad Thrasher
66 Corvair - Weekend Cruiser
90 4 Runner - Muddin |
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Brian Samba Moderator
Joined: May 28, 2012 Posts: 8340 Location: Oceanside
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Posted: Sat Nov 21, 2015 11:49 am Post subject: Re: Broken crank |
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I was gonna say you need one of these, but I think the GEX says enough.
_________________ Wash your hands
'69 Bug
'68 Baja Truck
'71 Bug
'68 Camper
Only losers litter |
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Glenn Mr. 010
Joined: December 25, 2001 Posts: 76760 Location: Sneaking up behind you
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Posted: Sat Nov 21, 2015 12:07 pm Post subject: Re: Broken crank |
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vugbug68 wrote: |
It is a forged German crank so I'm sorta puzzled as to why it broke, but then again I did find the GEX stamp so that might be the answer. |
It was most likely cracked when they threw it together. _________________ Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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[email protected] Samba Member
Joined: August 03, 2002 Posts: 12785 Location: Salt Lake City, Utah
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Posted: Sat Nov 21, 2015 12:45 pm Post subject: Re: Broken crank |
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that case is awfully oily for a 1 year old engine, just saying. There were other issues you either aren't mentioning, or aren't aware of... _________________ It's just advice, do whatever you want with it!
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ps2375 Samba Member
Joined: April 24, 2014 Posts: 2471 Location: Meridian,ID
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Posted: Sat Nov 21, 2015 1:08 pm Post subject: Re: Broken crank |
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vugbug68 wrote: |
It lasted 1 year of daily driving (in my friends car) then just broke. |
Ya, that's a good one. I used the same line when the trans on our riding lawnmower developed a hole in it. I'm sure it had nothing to do with the wheelies it was doing prior to the hole appearing.... |
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vugbug68 Samba Member
Joined: June 25, 2006 Posts: 2696 Location: sacramento
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Posted: Sat Nov 21, 2015 1:19 pm Post subject: Re: Broken crank |
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[email protected] wrote: |
that case is awfully oily for a 1 year old engine, just saying. There were other issues you either aren't mentioning, or aren't aware of... |
The engine was built many years ago, it sat in my friends garage for a while and already oily when we put it in the car. I've seen engines that were much nastier than this with a perfectly fine crank. There were no other problems that would make me suspect the crank might break in half. _________________ 71 Super - Backroad Thrasher
66 Corvair - Weekend Cruiser
90 4 Runner - Muddin |
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vugbug68 Samba Member
Joined: June 25, 2006 Posts: 2696 Location: sacramento
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Posted: Sat Nov 21, 2015 1:24 pm Post subject: Re: Broken crank |
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ps2375 wrote: |
vugbug68 wrote: |
It lasted 1 year of daily driving (in my friends car) then just broke. |
Ya, that's a good one. I used the same line when the trans on our riding lawnmower developed a hole in it. I'm sure it had nothing to do with the wheelies it was doing prior to the hole appearing.... |
Wheelies on a riding lawn mower? Now that's a good one, you got a hemi in that thing? _________________ 71 Super - Backroad Thrasher
66 Corvair - Weekend Cruiser
90 4 Runner - Muddin |
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VWCOOL Samba Member
Joined: June 02, 2006 Posts: 1821 Location: Down under
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Posted: Sat Nov 21, 2015 1:57 pm Post subject: Re: Broken crank |
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vugbug68 wrote: |
[email protected] wrote: |
that case is awfully oily for a 1 year old engine, just saying. There were other issues you either aren't mentioning, or aren't aware of... |
The engine was built many years ago, it sat in my friends garage for a while and already oily when we put it in the car. I've seen engines that were much nastier than this with a perfectly fine crank. There were no other problems that would make me suspect the crank might break in half. |
So, it wasn't built one year ago and done only daily driving since - as your first post implied? |
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campingbox Samba Member
Joined: November 14, 2000 Posts: 10192 Location: Petaluma, CA
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Posted: Sat Nov 21, 2015 2:04 pm Post subject: Re: Broken crank |
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Lets see some close ups of the crank journals near where it's cracked. Sometimes if the crank is reground without a radius on the corners they will crack. Sometimes parts just break. |
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Floating VW Samba Member
Joined: April 28, 2015 Posts: 1596 Location: The South Zone
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Posted: Sat Nov 21, 2015 2:16 pm Post subject: Re: Broken crank |
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Having never experienced a broken crank before, I gotta say I'm curious as to what exactly happens when it lets loose. I mean, does it all of a sudden go KAPWING! and sieze up right then and there, or does the motor keep chugging along just on the back two cylinders and for some reason the car doesn't go anywhere when you let out on the clutch? _________________ "It's time you started treating people as individuals, rather than mathematically predictable members of an aggregate set, regardless of how well that works." |
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Bruce Samba Member
Joined: May 16, 2003 Posts: 17273 Location: Left coast, Canada
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Posted: Sat Nov 21, 2015 2:20 pm Post subject: Re: Broken crank |
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When the crank breaks, all 4 cylinders are still firing and all the pistons are going up and down the bores. It just makes a lot of noise. _________________
overheard at the portland Swap Meet... wrote: |
..... a steering wheel made from a mastadon tusk..... |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Sat Nov 21, 2015 2:47 pm Post subject: Re: Broken crank |
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just wondering..what pully was on it? |
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vugbug68 Samba Member
Joined: June 25, 2006 Posts: 2696 Location: sacramento
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Posted: Sat Nov 21, 2015 4:20 pm Post subject: Re: Broken crank |
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VWCOOL wrote: |
vugbug68 wrote: |
[email protected] wrote: |
that case is awfully oily for a 1 year old engine, just saying. There were other issues you either aren't mentioning, or aren't aware of... |
The engine was built many years ago, it sat in my friends garage for a while and already oily when we put it in the car. I've seen engines that were much nastier than this with a perfectly fine crank. There were no other problems that would make me suspect the crank might break in half. |
So, it wasn't built one year ago and done only daily driving since - as your first post implied? |
Yeah I didn't word the first post correctly, I assume GEX built it years ago, it was a longblock and we added everything to make it a turnkey which was a little over a year ago. It ran real good, never had a problem until it started clunking _________________ 71 Super - Backroad Thrasher
66 Corvair - Weekend Cruiser
90 4 Runner - Muddin |
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Floating VW Samba Member
Joined: April 28, 2015 Posts: 1596 Location: The South Zone
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Posted: Sat Nov 21, 2015 4:46 pm Post subject: Re: Broken crank |
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One more question: I can see how 2 and 4 would keep firing, but how the hell do 1 and 3 manage, what with no longer being physically connected to either the valve train or the ignition system? That boggles my mind! _________________ "It's time you started treating people as individuals, rather than mathematically predictable members of an aggregate set, regardless of how well that works." |
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campingbox Samba Member
Joined: November 14, 2000 Posts: 10192 Location: Petaluma, CA
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Posted: Sat Nov 21, 2015 5:10 pm Post subject: Re: Broken crank |
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Floating VW wrote: |
One more question: I can see how 2 and 4 would keep firing, but how the hell do 1 and 3 manage, what with no longer being physically connected to either the valve train or the ignition system? That boggles my mind! |
I've broken two cranks, and both were hairline cracks all the way through. The crack was kind of jagged in spots, and went through at an angle. The engine will keep running for a while since the two halves are kind of wedged together. It just makes a minor noise at first but will progressively get louder and louder until you realize something catastrophic is wrong. I'm sure at some point it would stop running, but I would think most people have the common sense to turn the car off before that happens to limit the carnage. The first time this happened to me it was on a 36hp engine and it ruined the case. The second time was on a 1600sp and everything inside was fine. |
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HRVW Samba Member
Joined: May 01, 2011 Posts: 2531 Location: Rosarito, Mexico
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Posted: Sat Nov 21, 2015 5:57 pm Post subject: Re: Broken crank |
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Lugging an engine at LOW speed in 3rd or 4th gear will snap a crank. |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Sat Nov 21, 2015 6:08 pm Post subject: Re: Broken crank |
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Hard to guess the cause.
It could have been damaged and not straightened properly, or maybe it has a million miles on it.
The few GEX cranks I've checked they were not ground straight at all. Must not have understood how to straighten them. Only worse work I ever saw far as runout was in a tractor engine rebuilt by a vocational training program. |
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KTPhil Samba Member
Joined: April 06, 2006 Posts: 33883 Location: Conejo Valley, CA
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Posted: Sat Nov 21, 2015 6:46 pm Post subject: Re: Broken crank |
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campingbox wrote: |
Lets see some close ups of the crank journals near where it's cracked. Sometimes if the crank is reground without a radius on the corners they will crack. Sometimes parts just break. |
X2. This happened to a friend's engine. Ran for maybe 1000 miles (I can't remember exactly), and the warning was a knocking and oil light flickering at higher and higher idle speeds. We pulled everything off look for the problem. Split the case and still didn't see anything. Went to lift the crank off the case half and only half of it came out! Bingo!
Last edited by KTPhil on Sun Nov 22, 2015 2:54 pm; edited 1 time in total |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Sun Nov 22, 2015 10:00 am Post subject: Re: Broken crank |
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I had a friend bring us his duster and said the crank was broken in 2 peices... he drove it to our speed shop/chassie shop...said to just put a crank in it...or a motor witch was cheeper.so i pulle it out and......it was broken in 2 totaly seprate peices, he had been driving it for mover 2 months like that. I just stuck in another low cr 318 we had laying around.and away he went.cheep. I miss those days. |
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williamM Samba Member
Joined: August 07, 2008 Posts: 4333 Location: southwest Arizona
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Posted: Sun Nov 22, 2015 10:46 am Post subject: Re: Broken crank |
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I broke one in dads ghia. It made a loud bang and clunked all the way home. No damage- threw a new crank and away it went- In the bus that towed the jeep and motorcycle to Or. from NJ.- THEN it had to be rebuilt. _________________ some days I get up and just sit and think. Some days I just sit.
opinion untempered by fact is ignorance.
Don't step in any! |
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