#2 Rod bearing failure....why?
#1
Drifting
Thread Starter
#2 Rod bearing failure....why?
What is it about the #2 rod bearing and it's failures? Is it unique to only the higher HP engines or does the N/A suffer this malady as well? I pulled my rod bearings when the oil pan gasket was replaced and even though they all looked like new, I replaced them, nonetheless. I'm hoping this will prevent any problems in the future, if the N/A among the affected motors.
#2
Rainman
Rennlist Member
Rennlist Member
I just tore down an all-stock 951 engine and it had SHREDDED the #2 bearing. Nothing but shrapnel left over, and the crank journal is ground down 0.6mm.
It's due to the oil supply to the bearing - flow isn't that great to begin with, and starving it in hard corners etc doesn't help.
It's due to the oil supply to the bearing - flow isn't that great to begin with, and starving it in hard corners etc doesn't help.
#3
Race Director
oil flow is weak to the #2 bearing. It works fine in normal street driving when the system is working well. However when have more hp, more rpm, more cornering loads, higher oil temps, worn components ... it all take margin away and increases possiblity of starving the bearing for oil. Once it does even for a second it spins and bang...
#4
Administrator - "Tyson"
Lifetime Rennlist
Member
Lifetime Rennlist
Member
oil flow is weak to the #2 bearing. It works fine in normal street driving when the system is working well. However when have more hp, more rpm, more cornering loads, higher oil temps, worn components ... it all take margin away and increases possiblity of starving the bearing for oil. Once it does even for a second it spins and bang...
I autocrossed it once, maybe that did it.
#5
I was worried about mine when I autocrossed it so I added an extra 1/4 quart of oil. I figured that wouldnt be enough to overfill and foam but would give me a tiny amount of insurance.
#6
Nordschleife Master
It happens and there are numerous precautions to avoid it. Cross drill #2 crank journal, oil pick-up tube shroud, sump baffle plate, windage ports. Tracking and autocrossing will promote failure due to higher g's not normally seen on the street.
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#9
Late Porkchops
Rennlist Member
Rennlist Member
Just like you I replaced all mine when I was going all through the car at 91,000 miles. Just because. And just for insurance.
Interestingly when we were going out for a track day I added about 1/3 quart to the oil system which was measured and full at the mark on the stick and freshly changed too. I have always had the oil pressure gauge be bouncing around when the oil is hot and when the car comes back to idle. After adding the 1/3 quart the oil pressure settled nicely at idle. This was in just street driving. It seems it likes it.
Interestingly when we were going out for a track day I added about 1/3 quart to the oil system which was measured and full at the mark on the stick and freshly changed too. I have always had the oil pressure gauge be bouncing around when the oil is hot and when the car comes back to idle. After adding the 1/3 quart the oil pressure settled nicely at idle. This was in just street driving. It seems it likes it.
#11
Rennlist Member
my car is in the shop having rod end bearings replaced as we speak, for the first time since I've owned it, and after 4 full seasons of racing. Will be interesting to see their condition.
#12
Instructor
LR opens the journal walls to stop foaming, see link...approx 2/3rds way down page.
http://www.lindseyracing.com/hptalk/0808.htm
http://www.lindseyracing.com/hptalk/0808.htm
#13
1. Are there any known instances where these 4 precautions, when taken, have still allowed a spun #2?
2. Or are these 4 steps taken together such a rarity among racers/ x-crossers; thus too small a population to make measure?
3. Lastly, which of those 4 is least costly and thus best solution for strictly street drivers?
TIA!