[Efthreeoh]

Originally Posted by sabino56

Yeah, I’d guess this was the decision which led to the problem. As an engineer, I’ve lived thru the experience of a “great” idea leading to a host of resulting “minor” problems.

It is/was a great idea for performance and handling to make the block lighter. But now you can’t let steel or iron touch the magnesium so you need to use aluminum bolts if attaching something steel (like the oil pan on my 2006 N52).
Al doesn’t have same modulus as steel so clamping force is less. You can’t fit larger diameter bolts to make up for the lower modulus. To max clamping force you torque to yield but now they are one time use. It’s ok, they won’t have to be replaced during warranty.

I’m sure someone was worried about potential for the gasket to shrink resulting in an oil leak but unlikely anyone had good data on the problem, or at least good enough to offset the value of what a lighter block would bring to the table (which is easily measurable and quantifiable). When you’ve used steel bolts in past and had plenty of clamping force, gasket shrinkage wasn’t something likely to be high on list of problems to study.

All that said, I like that BMW (at least then) put performance at the top of their priorities. I’m ok with the trade off for performance vs PITA oil leaks.
Kinda like my girlfriend - love her dearly and wouldn’t want another. There are a few things which bug me.. but not dealbreakers.

The gasket design just sucks, plain and simple. The aluminum pan bolts have enough clamping force; the pan uses 28 bolts with short spacing between them.

[oVeRdOsE.]

Originally Posted by Efthreeoh

The gasket design just sucks, plain and simple. The aluminum pan bolts have enough clamping force; the pan uses 28 bolts with short spacing between them.

i agree. If it was the gasket material, be sure aftermarket would fix that.

Like I said, people should compare with other non-leaking brand, bmw are too thin with way too many sharp angles and less contact surface. Pretty simple.

even plumber would say this with massive hydraulic system with flanges and gaskets.

[sabino56]

Originally Posted by Efthreeoh

The gasket design just sucks, plain and simple. The aluminum pan bolts have enough clamping force; the pan uses 28 bolts with short spacing between them.

Agree. I didn’t mean to say it was a good design. Just my thoughts on how they ended up shipping a bad design. Engineering for big companies never have enough resource so they end up just working on problems which are brightly burning. 3-4 years after shipping field complaints put it on a list of something to address going forward but no one is going to go back and fix the old design for something like this. There has to be a liability problem or a big warranty expense exposure to go backwards.

[Efthreeoh]

Originally Posted by sabino56

Agree. I didn’t mean to say it was a good design. Just my thoughts on how they ended up shipping a bad design. Engineering for big companies never have enough resource so they end up just working on problems which are brightly burning. 3-4 years after shipping field complaints put it on a list of something to address going forward but no one is going to go back and fix the old design for something like this. There has to be a liability problem or a big warranty expense exposure to go backwards.

I agree. And what is amusing is the N52 has a mid-block section that bolts to the upper block, and the oil pan bolts to it. That mid-block part line is sealed at the factory with a special gasket compound in liquid form that sets up over time. The N52 rarely leaks at mid block. I get the oil pan is the entry point to the engine's bottom end and needs to be removable for servicing, but a better gasket should have been imagined.

[StradaRedlands]

Originally Posted by crashoverride

Not a fan boy but I'm going to push back a bit. These cars are going on twenty years. There isn't very many other brands out there that have cars that still look and drive like an e90.
In addition these are built as higher end sports cars not a simple basic four banger. You would be hard pressed to find any brand 2006-ish car that doesn't leak oil.

I don't know about that... my '06 Mazda3 has zero leaks. My mom's '07 Toyota Matrix similarly has zero leaks. Our '07 Benz had zero oil leaks till it met its demise. Mercedes, Mazda & Toyota can source a proper gasket that lasts 17 years and 140k miles with no drama. Seems to be a BMW problem.

[lowrydr310]

Originally Posted by StradaRedlands

I don't know about that... my '06 Mazda3 has zero leaks. My mom's '07 Toyota Matrix similarly has zero leaks. Our '07 Benz had zero oil leaks till it met its demise. Mercedes, Mazda & Toyota can source a proper gasket that lasts 17 years and 140k miles with no drama. Seems to be a BMW problem.

My immediate family has owned many Honda/Acura and Toyota/Lexus over the years, and both those brands had valve cover gasket leaks around 15 years and 200K miles. Much better than the E9x but not immune to developing leaks.

Here's a fun fact. I have a 2011 Pilot and there's a VTEC solenoid/valve that bolts to the cylinder head of the front bank that is notorious for leaking. Ironically it's the exact same design as our beloved N52/N54 oil filter housing gasket, sandwiched between two layers of flat metal to contain pressurized oil. Mine lasted 12 years; though I think it's climate related. It never leaked until I took the car to a place with single digit temperatures for a week. Oh and the failure symptoms were identical to the N52/N54 OFHG leak - oil spews all over the alternator directly underneath!

[E93Seattle (Racerbruce)]

i had a 71 datsun 510 2 dr that i purchased in 77 @70K miles on it; i pulled the engine and totally rebuilt it @135k miles and there were zero oil leaks present when the engine was pulled and rebuilt.

my 07 z4mr s54 was purchased in 10 @12k miles on it; when i sold it in oct 22 @69k miles it had a minor oil leak that may have been related to the head gasket on the right side where an oil galley drain from the head made its way back into the block.