406 teardown...
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
All good descriptions. I think the "changing pressure" dialogue was only meant to explain why the front bearing went first. Without question, the engine site oiled last will be oiled least. If there is not an obvious reason for oil starvation found during engine teardown, the oil supply system needs to be upgraded (higher pressure spring, larger pump, etc. are all options on how to do that).
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
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Isn't this fun?
So what if you get some air in the pickup and pressure drops and then is grabbing bubbles, or cavitating etc etc.......
Could the *rearward* bearings still possibly still be getting enough oil/bubbles etc to help keep them alive in a marginal situation and the front ones just never get that benefit?
I agree 100% with all the hyd theory...it's more than that....it's fact......but rod issues at the front of stock oiling sytem motors have always seemed to be much more prevalent than the rears. These are the things that brought priority main oiling to all the aftermarket blocks.
I think when you have a marginal setup anyway, and you're right on that edge....you will see the issues.
That said..until he does some real close looking....I'm not ruling out some detonation damage on that cylinder...poor intake flow? or whatever that might have hammered that one rod and in fact his system IS actually pretty decent as proven by the 80+ runs. But if it's marginal and is getting air, cavitation or whatever.....it could easily have scuffed that bearing a little bit over a long period of time and it finally just grabbed the crank with the N20 added to the mix.
JIM
So what if you get some air in the pickup and pressure drops and then is grabbing bubbles, or cavitating etc etc.......
Could the *rearward* bearings still possibly still be getting enough oil/bubbles etc to help keep them alive in a marginal situation and the front ones just never get that benefit?
I agree 100% with all the hyd theory...it's more than that....it's fact......but rod issues at the front of stock oiling sytem motors have always seemed to be much more prevalent than the rears. These are the things that brought priority main oiling to all the aftermarket blocks.
I think when you have a marginal setup anyway, and you're right on that edge....you will see the issues.
That said..until he does some real close looking....I'm not ruling out some detonation damage on that cylinder...poor intake flow? or whatever that might have hammered that one rod and in fact his system IS actually pretty decent as proven by the 80+ runs. But if it's marginal and is getting air, cavitation or whatever.....it could easily have scuffed that bearing a little bit over a long period of time and it finally just grabbed the crank with the N20 added to the mix.
JIM
