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Old 04-07-2013, 02:59 AM
twinockchef's Avatar
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Join Date: Jun 2007
Location: Savoy, Texas
Posts: 353
Broken Crankshaft

Well 'Hairball' has struck again with a broken crankshaft. It happened last month. I have been very busy with school so I have only been able only able to devote eight hours each weekend. Metric Motors provided me with a new crankshaft (plus flywheel, balancer, a seal kit, and bearings) at a very reasonable cost.

During the proccess I decided to replace all of the oil, transmission, power stearing, and fuel line hoses. There is a local shop which was able to replace all the hoses and still keep the orininal fittings, at a very reasonable cost. All of the metal oil and transmission lines were also looking ragged. So I sand blasted them and spray painted them. All of the rubber parts on the clamps were replaced.

The engine is back in and I should have Hairball running Sunday afternoon.
There was just one problem I have three things left over and I can not figuire out where they go.
The person who correctly identifies them will get the booby prize.
Britton McIntyre

68 280 SE coupe 'Hairball'
70 280 SL
71 280 SEL - RIP May 2010
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Old 04-07-2013, 10:03 AM
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Join Date: Mar 2006
Location: Atlanta, GA
Posts: 121
I don't recognize the first bolt. But the second one is the cap that goes on the end of the timing chain tensioner. The third bolt looks like a cylinder head bolt.

Hope that helps,
John Heller
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Old 04-07-2013, 10:40 AM
JMela's Avatar
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Join Date: Apr 2003
Location: Brooklyn, NY/ Minneapolis, MN
Posts: 987
Guessing 1st bolt is an engine accessory mounting bolt.

How did that crankshaft sound when it went? Any other damage?
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Old 04-07-2013, 11:07 PM
twinockchef's Avatar
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Join Date: Jun 2007
Location: Savoy, Texas
Posts: 353
I did not have any left over parts. The parts pictured are a flex disk bolt, timming tensioner nut/cap, and a head bolt. I did this because everyone hears of the stories about finishing a project and having extra parts which did not happen to me. So I picked a few extremely important parts to have fun with. (68_280SE was correct on two of them. "Two out of three ain't bad.")

The crazy thing about the crankshaft was at first I believed it had just a big crack, on one of the counter weights, because the car worked but with a loud noise from the engine until I parked it in my shop.
Metric Motors informed me, from just a photo of the the crackshaft through the oil pan, that the engine was running very rich and was the probably of the shaft failure. I was lucky with other damage. It was only a broken shaft and a very small amount of wear on the bearing in front of the break which had a small amount of shavings.
Surprisingly replacing the crank shaft is not as difficult as you might think. As long as you have a engine hoist and stand it can be done.
Britton McIntyre

68 280 SE coupe 'Hairball'
70 280 SL
71 280 SEL - RIP May 2010
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Old 04-08-2013, 12:52 AM
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Join Date: Jul 2011
Posts: 526
Any idea of why it broke? Is this a weak point in those engines?
It's pretty uncommon for a crank to break.

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Old 04-08-2013, 01:54 PM
Tony H's Avatar
Join Date: Oct 2005
Location: Bandon, Oregon
Posts: 1,050
Had the crank been magnifluxed before it went into the engine? I know straight 6's have harmonics and the long crank can be a problem but one would think a 7 bearing engine would be very strong. Sounds like you recovered pretty well though.
Tony H
111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux-Dad bought new
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Old 04-09-2013, 12:34 AM
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Join Date: Dec 2010
Posts: 1,852
This head bolt is the one used for the cam bearings - the shorter one holds the cam cover brackets in place.
Chain tensioner cap and flex disc screw which is the longer one used to fix the cross joint in place.
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