Hi!
I recently rebuilt and stroked my TJ's motor to a 4.6L. During break in, I would get a minute or two of what I initially thought was an exhaust leak but may have actually been detonation and/or something internal on the bottom end. Pulled the engine out and apart, rod bearing #3 was nearly welded to the crankshaft. Every other bearing looked perfect, main bearings good, cylinder walls good, camshaft and lifters looked surprisingly good as well.
My question is what would cause a single point of failure like this? Plugged oil galley? Bad clearances? I'm by no means an engine guy so crowdsourcing some opinions.
What caused this rod bearing failure?
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- Posts: 2
- Joined: October 18th, 2023, 4:53 pm
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What caused this rod bearing failure?
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- Cheromaniac
- I live here
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Re: What caused this rod bearing failure?
Possibly either one or both of the two.
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
1995 Mustang GT - 4AT - Modded Sold
2006 Mustang GT - 5MT - Modded Midlife Crisis Car
1995 Mustang GT - 4AT - Modded Sold
2006 Mustang GT - 5MT - Modded Midlife Crisis Car
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- Strong Poster
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Re: What caused this rod bearing failure?
Did you check your bearing clearances and if so what were they?
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- Donator
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Re: What caused this rod bearing failure?
Because of where the damage is i would think it was trash in the crankshaft oil hole to the rod bearing.it looks like, from what i can see in the pictures, that the damage is in line with the oil hole in the crank.
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- Donator
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Re: What caused this rod bearing failure?
What connecting rods did you use?
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- Where's the "any" key?
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Re: What caused this rod bearing failure?
What Russ said; did you check ALL the bearing clearances when you assembled?
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- Posts: 2
- Joined: October 18th, 2023, 4:53 pm
- Stroker Displacement: 4.6
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Re: What caused this rod bearing failure?
This ended up being the root cause..found a price of debris in the block (no idea where from). Machine shop pretty much said the same thing you did that it was likely debris coming in from oil galley. Machine shop also said if it was bad bearing clearances I would've seen wear across the entire bearing.
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