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Discussion Starter · #1 ·






I never thought this would happen.

The crank snapped at WOT; Bumping the rev limiter; in 4wd; 1st gear

I took the engine apart, everthing is very clean for 200 000km (125K miles) with 170 000 km supercharged. The block, heads, rods and pistons were NOT damaged. I suspect the crankshaft had a micro fracture. this is not normal... :confused:

I had this slight vibration in the engine at idle that I was never been able to fix. I since replaced the engine with a V6 from a Tundra with 20 000 miles.

While I had the chance, I replaced the flywheel with an Aluminium one from LC Eng and a clutch kit from ACT.
 

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d0ubledown said:
holy shit..thats unreal! curious..what situation were you in that you needed to be bouncing of the limiter in 1st gear 4WD?
Launch at the drag strip?
 

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Discussion Starter · #6 ·
I was returning to trade school one night. It was really cold... -25 C (-25 degree Celsius = -13 degree Fahrenheit). Yes it can get really cold in January around here. At this temp, the truck has a LOT of power, and I enjoyed it so I decided to have a little fun. I was just taking off at a light in 4wd on pavement. Didn't do a drop clutch (I don't like to shock my drivetrain). So I took off slowly in 1st and at about 2000RPM, nailed the trottle. The 4 tires(31 inch) started spining because of the cold pavement and dense, o2 packed air, while the engine reached max RPM, tires hunting for traction.... Then it happen... that awful noise... put it immediately in neutral and the engine died. It started it again to find a place to park it. It was a very loud knocking.

The next morning, I poped the hood to find my belts were all loose... Broken Crank!

After I replaced the engine; I tore the old one apart. I was amazed at the overall condition especially because it was driven very hard to redline every day throughout it's life. All the piston rings were not seized at all, no ridge that you could feel in the cylinders; all the bearings were still polished and score free and no pitting on top of the pistons or CC. The seats for the exhaust valves were starting to show signs of wear tough. This is one stout little engine. I'm a Toy tech and we never have problems with these engines. In all the years I've browsed the forums, I've never heard of a broken crankshaft in a 5vz...
 

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Discussion Starter · #8 ·
thehackman15 said:
why were you driving on the pavement in 4wd?
I don't drive on pavement with the front end engaged unless I want to have fun in 1st gear. Hot asphalt give a better coefficient of traction. The opposite is also true. 4wd does not affect anything in a straight line b/c there's no speed difference between the front and rear tires.... unless tires aren't rotated or have different sizes.
 

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BlownToy said:
I was returning to trade school one night. It was really cold... -25 C (-25 degree Celsius = -13 degree Fahrenheit). Yes it can get really cold in January around here. At this temp, the truck has a LOT of power, and I enjoyed it so I decided to have a little fun. I was just taking off at a light in 4wd on pavement. Didn't do a drop clutch (I don't like to shock my drivetrain). So I took off slowly in 1st and at about 2000RPM, nailed the trottle. The 4 tires(31 inch) started spining because of the cold pavement and dense, o2 packed air, while the engine reached max RPM, tires hunting for traction.... Then it happen... that awful noise... put it immediately in neutral and the engine died. It started it again to find a place to park it. It was a very loud knocking.

The next morning, I poped the hood to find my belts were all loose... Broken Crank!

After I replaced the engine; I tore the old one apart. I was amazed at the overall condition especially because it was driven very hard to redline every day throughout it's life. All the piston rings were not seized at all, no ridge that you could feel in the cylinders; all the bearings were still polished and score free and no pitting on top of the pistons or CC. The seats for the exhaust valves were starting to show signs of wear tough. This is one stout little engine. I'm a Toy tech and we never have problems with these engines. In all the years I've browsed the forums, I've never heard of a broken crankshaft in a 5vz...
I woudl have guessed from the descriptive tale that you write for some import tuner mag or something...its supposed to be a compliment.
 

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The crank snapped at WOT; Bumping the rev limiter; in 4wd; 1st gear
Yeah sounds like a real torture test. Of course metal is more brittle when cold too, had you gotten it warmed up yet?
 

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well..its cool that nothing else busted but that sux big ones
 

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Discussion Starter · #13 ·
Yeah sounds like a real torture test. Of course metal is more brittle when cold too, had you gotten it warmed up yet?
That happened while coming back from a 1 hour trip.

Torture test? not really; my description of what happened sounds worse than what actually happened. It's not like it bounced on the limiter for 5 secs...

How many thousands of people have bounced the limiter while being stuck in the mud/snow...?

Anyways, I'm happy that I now have a fresh engine, and spare block, heads, manifold...little project for the future hehehe

The replacement engine still had the original NGK/Denso spark plug combo from the factory with minimal wear meaning it's a genuine low mileage mill. :D
 
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