[435iKev]

I recently spun my rod bearings on my 435i RWD. It was around 109k miles, FBO Stage 2 BM3. I just sourced a new motor, 70k miles for 3 grand. I’m planning on replacing a few components on this new motor and had a couple questions.

1) I plan to replace the valve cover gasket, oil pan gasket, oil pressure control valve, plugs/coils, and injectors. I was wondering what other components I should replace while the motor is out.

2) I’m currently running Bootmod3 Stage 2(Agg) OTS tune. I’m obviously going to keep it on stock tune for a while but I was wondering how long I should keep it stock for. I still plan on flashing back to Stage 2 sometime but when would be a good time to do that?

3) I’m also adding the MMR oil sump baffle. I know the S55 oil setup is way better but I can’t afford it. Anyone who has the MMR setup please let me know your experience. I’m 99% sure the shitty oil pan design on the N55’s caused the spun rod bearings. I’ve never tracked the car and don’t plan to. I do drive decently hard and take it out on the occasional canyon sends.

Open to any advice thanks!

[arekuf3x]

Was any work done on oil system before it let go, like oil filter housing gasket? From my research, MMR should help especially under hard braking. But a lot cars let go because oil system wasn’t primed after ofhg or low on oil.

[terryd5150]

Replace the rod bearings on the new (used) engine. If you're doing the baffle, you'll be right there at them anyway.

Also, do the oil filter housing gasket.

Make sure to prime the new engine before firing it up.

[435iKev]

Originally Posted by arekuf3x

Was any work done on oil system before it let go, like oil filter housing gasket? From my research, MMR should help especially under hard braking. But a lot cars let go because oil system wasn’t primed after ofhg or low on oil.

No work was recently done on the oil system before it let go. I did have the “low engine oil light” but quickly added a quart of oil.

[435iKev]

Originally Posted by terryd5150

Replace the rod bearings on the new (used) engine. If you're doing the baffle, you'll be right there at them anyway.

Also, do the oil filter housing gasket.

Make sure to prime the new engine before firing it up.

Got it! I’ll definitely replace the OFHG. My mechanic is doing the motor replacement so I’m sure he knows the procedures such as priming.

[thejeremyman9]

Originally Posted by 435iKev

No work was recently done on the oil system before it let go. I did have the “low engine oil light” but quickly added a quart of oil.

This was probably why. Did you ever get oil pressure warning or just to add oil?

[435iKev]

Originally Posted by thejeremyman9

This was probably why. Did you ever get oil pressure warning or just to add oil?

Just the add oil warning. To be honest it was completely my fault, should’ve taken better care of the car. It’s my first Bimmer so I didn’t fully understand the amount of maintenance these cars need. Expensive lesson but I will definitely take a lot better care of the new motor.

[435iKev]

My mechanic also told me to replace the Oil Pressure Control Valve while the motor is out. What does this do and is it necessary to change? He told me this could’be been a cause for my spun rod bearings.

[mecheng77]

Originally Posted by 435iKev

Got it! I’ll definitely replace the OFHG. My mechanic is doing the motor replacement so I’m sure he knows the procedures such as priming.

No, most engines don’t require priming so most mechanics don’t do it.

If the car said engine low, that only means it was down 1L, I wouldn’t worry that you caused it but being stage 2 doesn’t help.

Put new bearings for sure and the baffle

[SpoolinAddict]

Originally Posted by 435iKev

I recently spun my rod bearings on my 435i RWD. It was around 109k miles, FBO Stage 2 BM3. I just sourced a new motor, 70k miles for 3 grand. I’m planning on replacing a few components on this new motor and had a couple questions.

1) I plan to replace the valve cover gasket, oil pan gasket, oil pressure control valve, plugs/coils, and injectors. I was wondering what other components I should replace while the motor is out.

2) I’m currently running Bootmod3 Stage 2(Agg) OTS tune. I’m obviously going to keep it on stock tune for a while but I was wondering how long I should keep it stock for. I still plan on flashing back to Stage 2 sometime but when would be a good time to do that?

3) I’m also adding the MMR oil sump baffle. I know the S55 oil setup is way better but I can’t afford it. Anyone who has the MMR setup please let me know your experience. I’m 99% sure the shitty oil pan design on the N55’s caused the spun rod bearings. I’ve never tracked the car and don’t plan to. I do drive decently hard and take it out on the occasional canyon sends.

Open to any advice thanks!

Just curious, how much is the mechanic charging you for the swap? Labor and cost of the new used engine.

[arekuf3x]

If it was low on oil, it’s either burning it or leaking. N55s don’t like to run low on oil. Did you drive it aggressively on low oil? That would definitely kill rod the bearings.

[435iKev]

Originally Posted by SpoolinAddict

Just curious, how much is the mechanic charging you for the swap? Labor and cost of the new used engine.

2k for labor and around 4K for the motor (used). Since the engine was already out I had my mechanic change all the gaskets and solenoid. It’s been a year and I haven’t have any problems with the replacement engine.

[Polo08816]

Originally Posted by 435iKev

2k for labor and around 4K for the motor (used). Since the engine was already out I had my mechanic change all the gaskets and solenoid. It’s been a year and I haven’t have any problems with the replacement engine.

Btw, there are a LOT of junk used N55 motors around.

I tried 2 of them before just opting for a new N55 from BMW.

[scotthilly]

Originally Posted by Polo08816

Btw, there are a LOT of junk used N55 motors around.

I tried 2 of them before just opting for a new N55 from BMW.

How much did it cost to get the new N55 from BMW? I have a e90, totally stock, great maintenance history but am terrified of this happening.

[monster6a2]

Originally Posted by 435iKev

Got it! I’ll definitely replace the OFHG. My mechanic is doing the motor replacement so I’m sure he knows the procedures such as priming.

Originally Posted by scotthilly

How much did it cost to get the new N55 from BMW? I have a e90, totally stock, great maintenance history but am terrified of this happening.

Even though you might have the “bad” rod bearings out of the s65, if you properly maintain your engine, monitor your oil pressure, wait till your oil temp is in the green before inducing high rpm, and change ur oil every 3-4k miles, you shouldn’t have much to worry about.

Contrary to what many people say, the N55 is a reliable engine if it’s maintained well. Make sure you aren’t in need of any gaskets as this might contaminate your oil with unwanted debris, but over all, based on your great maintenance history, your engine should last for a long time. One thing that is specifically mentioned in this thread and I cannot stress this enough. Any time you do any maintenance that disrupts the oil channel, ex your oil filter housing gasket, please prime the engine. There are many different ways to do it and it realistically takes 15 min at most. Doing so will ensure that there is no oil starvation to your rod bearings and should keep your engine running healthy for many miles to come.

At some point as well, I’d suggest replacing your belt along with the tensioner and other components regarding that area of the engine. The N55 is known to suck up the belts into the crank seal, which shears the belt which then gets into your oil. Watch for that as well

[Polo08816]

Originally Posted by scotthilly

How much did it cost to get the new N55 from BMW? I have a e90, totally stock, great maintenance history but am terrified of this happening.

https://www.getbmwparts.com/oem-part...ne-11002286626

About $13,500 (includes the core charge) since BMW won't take an engine back with a few holes through the engine block.

[F32Fleet]

Originally Posted by 435iKev

I recently spun my rod bearings on my 435i RWD. It was around 109k miles, FBO Stage 2 BM3. I just sourced a new motor, 70k miles for 3 grand. I’m planning on replacing a few components on this new motor and had a couple questions.

1) I plan to replace the valve cover gasket, oil pan gasket, oil pressure control valve, plugs/coils, and injectors. I was wondering what other components I should replace while the motor is out.

2) I’m currently running Bootmod3 Stage 2(Agg) OTS tune. I’m obviously going to keep it on stock tune for a while but I was wondering how long I should keep it stock for. I still plan on flashing back to Stage 2 sometime but when would be a good time to do that?

3) I’m also adding the MMR oil sump baffle. I know the S55 oil setup is way better but I can’t afford it. Anyone who has the MMR setup please let me know your experience. I’m 99% sure the shitty oil pan design on the N55’s caused the spun rod bearings. I’ve never tracked the car and don’t plan to. I do drive decently hard and take it out on the occasional canyon sends.

Open to any advice thanks!

Do you remember which bearing? Ex. No6