Busted Crank?
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Cross-Country
Joined: Oct 2004
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Busted Crank?
The Harmonic balencer busted off the front of my motor yesterday (4.0L 1999 4x4). It looks like the the actual crank shaft snapped just where the assembly is fastened to. Does anyone know if this is a common problem? My truck had 175000 KM but steel snapping doenst sound right to me. Do you think that other damage may have been done as I was doing 100 kph at the time or am I just looking at the crank? Also is it possible that some other internal engine failure would cause this part to bust like a faulty timing chain or somthing?
Thanks for any thoughts.
Thanks for any thoughts.
Cargo Master
Joined: Nov 2004
Posts: 2,858
Likes: 3
From: Friendswood, Texas
I've never heard of this happening before. My guess would be that you had some porosity in the forging, it developed into a crack over time and boom, it snapped. A real oddball but it could certainly happen. It's simple statistics. Somebody has to get that 1 crank out of 25,000 with a problem and unfortunately, you won the lottery. Sorry to hear about it. I have that engine in a 96 Explorer 4x4 and it's been great.
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Cross-Country
Joined: Oct 2004
Posts: 86
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I had the timing chain and cover replaced last year do you think that the mechanic could of done aything to cause this? It was only about 5000 to 8000 mile ago. Also to chain the crank does the engine have to be completely removed? If so I was thinking maybe I should just put a new one in.
Thanks guys.
Thanks guys.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
If you can get the timing cover & gearset, pan, and flywheel-back stuff off, you can do it w/o pulling the engine. You will be dripped on for days. I mean weeks. Way back when (bowtie) stove bolt six engines had manually adjusted clearance (shims) for the main bearings, I had one. Or rather my sister had one in Wisconsin in winter. She didn't take care of it and threw a rod. We pulled the crank out the bottom, had it welded and re-ground. Supposedly to spec. New bearings, and it wouldn't turn over with a crowbar. Needed shims for a supposedly 'spec' crankshaft.
It can be done.
Would I do it again? Nope. Bought a cherry picker and thanked my self every time I used it.
tom
It can be done.
Would I do it again? Nope. Bought a cherry picker and thanked my self every time I used it.
tom
Cargo Master
Joined: Nov 2004
Posts: 2,858
Likes: 3
From: Friendswood, Texas
Originally Posted by brian931
I had the timing chain and cover replaced last year do you think that the mechanic could of done aything to cause this? It was only about 5000 to 8000 mile ago. Also to chain the crank does the engine have to be completely removed? If so I was thinking maybe I should just put a new one in.
Thanks guys.
Thanks guys.
It was only about 5000 to 8000 mile ago.
If it were sonethign they did, I would think it would ahve blown in the fist 100 miles or so.
Also to chain the crank does the engine have to be completely removed? This would be the best way to do it. You can probably do it with the enigne in the vehicle if you absolutely had to - but the extra work required to remove the oil pan, etc. make pulling the engine the logical chioice. Makes doing any machine work a bunch easier with the engine out also.
If so I was thinking maybe I should just put a new one in.
There ae a lot of factors to consider here.
1 - Are there any other issues with the engine?
2 - What would it cost to repair?
3 - How many miles are on the engine?
4 - What is the condition of the truck?
5 - Is the truck worth throwing the money into or can a new truck be had for the same money or close to it??
6 - Will you be doing the work yourself or wil you have to pay to have it done?
7 - You should be able to find a decent low milage engine as a replacement. These engines are everywhere and they are pretty durable though I would certainly understand if you begged to differ. That said, I think you just got a bad one or a previous owner didn't take very good care of it.
Anway, sorry to hear about your truck going south on you. Hope it all turns out well.
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Post Fiend
Joined: Jan 2003
Posts: 9,748
Likes: 16
From: Connecticut
I've heard of a few rare occasions where the crank has snapped on the 4.0L OHV.
I agree, go with a used low mileage 4.0L from a junkyard.
I agree, go with a used low mileage 4.0L from a junkyard.
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Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
Being the lazy T**d that I have turned into since I was told to take a walk, I'd buy a decent used engine and pop it in. If I was really into stuff, I'd take my old one and do some 'magic' to it... and then pop it in..
tom
tom
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
mechanic either damaged the harmonic balancer, it's keyed shaft/bore or did not torque the bolt holding it to crank to specs.
impossible to prove now
put in a rebuilt short block with your heads, have them magnafluxed for cracks and valves ground, replace cams if worn and put in new chain/gears/tensioner/follower
you won't get full core charge with broken crank
will need a new harmonic balancer, do NOT mess with pulling an old one at used auto parts emporium....too many old ones out there that have damaged inserts
impossible to prove now
put in a rebuilt short block with your heads, have them magnafluxed for cracks and valves ground, replace cams if worn and put in new chain/gears/tensioner/follower
you won't get full core charge with broken crank
will need a new harmonic balancer, do NOT mess with pulling an old one at used auto parts emporium....too many old ones out there that have damaged inserts
Last edited by 96_4wdr; Apr 19, 2006 at 06:32 AM.
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