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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > I'm going to preventatively replace my 72K N55 rod bearings



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      09-24-2020, 08:16 PM   #287
Ozzie335i
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Not disagreeing with this possibility, but how could this explain the high number of failures shortly after OHFG gasket changes?
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      09-25-2020, 11:07 AM   #288
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Originally Posted by Ozzie335i View Post
Not disagreeing with this possibility, but how could this explain the high number of failures shortly after OHFG gasket changes?
You cant unless you know exactly what causes then to fail in the first place. But blindly replacing rod bearings you have to agree is not a fix of any sorts..

Not saying i would not like them to be replaced but i am more interested in a root cause.
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      09-27-2020, 08:53 AM   #289
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Is it safe to say the higher mileage N55's are "safe"?

I saw the list of failed cars, and they were all what I would call low mileage.
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      09-27-2020, 09:22 AM   #290
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You cant unless you know exactly what causes then to fail in the first place. But blindly replacing rod bearings you have to agree is not a fix of any sorts..
Exactly why I referred it as a bandaid. With the King bearings I feel that I've got that last bit of clearance so a tad more oil is in there to buy me some time should the hydraulic valve have a temporary hiccup. Or whatever is the cause. I got a new oil pan gasket in the process. I just buttoned up the bottom underneath with one of those cool new skid plates. Of course the new Eibach sway bar was first installed, tying the B12 kit together.
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      10-19-2020, 09:29 AM   #291
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Even before i decided to say anything about this valve and we have discussed this possibility before in this forum many times before, i struggle to understand how a 'Normally Open' valve that is in default poaitiin pressed open by a spring can fail. It my be possible that it gets stuck when it has already been actuated. Hard to say.

I guess it would be beneficial to remove and bench test this valve on motors that have seized.

You might not even have to apply and signal since if the theory is correct when you pull them they should be stuck engaged.
Yeah I can't see how this valve plays any kind of role. People having been coming up with these crackpot theories about EVERYTHING with BMW's. Since TIS gives you a part number run date they think that they can just relate failures to any part number change they can find without putting any thought into it or proving it. Just like 2011 BMW's have bad rods, right?

Rod bearing failures are seen in all N5x. N54's and newer N55's as well. How exactly would the issue relate to the electronic valve? The valve BYPASSES oil pressure. If it fails you would just get more pressure not low pressure. Makes 0 sense to blame this valve. The only place I can see it playing any kind of role is being slow to close back up when rpm's drop rapidly causing oil pressure to drop a bit more than it's supposed to. However, there is nothing to substantiate that. Nothing in N55 oil pressure logs look any different than N54 when decelerating and N54's don't have the valve. It's just another baseless theory.
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      10-21-2020, 08:07 PM   #292
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bbnks2, Pladi was just putting that theory out there. Until BMW comes clean all we have are theories. Likely these rides will all be in junkyards before we have a response. As I had an accident a year ago I still only have 3 or 4 K miles on my new King bearings. Fatty has a lot more. For my money I have a fresh rod bearing set and a new oil pan gasket. All is good for my little 183 cubic inch hot rod.
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