Jake's Epic BMW 135i Build Thread! (5+ Years of Ownership)
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Never re-use those oil and coolant lines. They are cheap shitty rubber. Replace all of them, especially at your high mileage, and especially while you still have the turbos out and hopefully haven't re-installed everything yet.
Once you have the car back together, in case you do not know the proper priming process for turbo replacements on N5x cars: (Assuming you have relieved fuel pressure and disconnected the fuel pump fuse and ran the car until it died prior to starting this project like you should have) - crank the engine (push the start/stop button) 7 times for 7 seconds each time to prime the turbo with oil. Reconnect the fuel pump fuse. Then run the car at WOT for 20 minutes before hopping on the highway and challenging everyone to a 60 roll.
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I'm really surprised the one series don't have a factory LSD besides the 1M? Is it available as a factory option at least?
No factory option. The first modern non-M car to get an optional LSD was the M235i.
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Never re-use those oil and coolant lines. They are cheap shitty rubber. Replace all of them, especially at your high mileage, and especially while you still have the turbos out and hopefully haven't re-installed everything yet.
Once you have the car back together, in case you do not know the proper priming process for turbo replacements on N5x cars: (Assuming you have relieved fuel pressure and disconnected the fuel pump fuse and ran the car until it died prior to starting this project like you should have) - crank the engine (push the start/stop button) 7 times for 7 seconds each time to prime the turbo with oil. Reconnect the fuel pump fuse. Then run the car for 2 minutes at idle, giving it no revs at all, then shut it off and let it cool. Once cool, start again for 15 minutes, again at idle with no revs. Shut it off and let it cool. Once cool, do a final run at 30 minutes, at idle, no revs.
I'm all for priming oil but what is the reason behind idling it for a combined 47 minutes? Are these engines prone to air bubbles trapped in the oil?
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Never re-use those oil and coolant lines. They are cheap shitty rubber. Replace all of them, especially at your high mileage, and especially while you still have the turbos out and hopefully haven't re-installed everything yet.
Once you have the car back together, in case you do not know the proper priming process for turbo replacements on N5x cars: (Assuming you have relieved fuel pressure and disconnected the fuel pump fuse and ran the car until it died prior to starting this project like you should have) - crank the engine (push the start/stop button) 7 times for 7 seconds each time to prime the turbo with oil. Reconnect the fuel pump fuse. Then run the car for 2 minutes at idle, giving it no revs at all, then shut it off and let it cool. Once cool, start again for 15 minutes, again at idle with no revs. Shut it off and let it cool. Once cool, do a final run at 30 minutes, at idle, no revs.
Ugh, it's like $500 for all new lines. That's a nice chunk of LSD money. I'll be cleaning them up, blowing compressed air through them, and inspecting them. I want to replace them, but was very careful about removing them. We'll see.
I didn't relieve fuel pressure and let the car die. I was planning on disconnecting the injector harness and letting the engine crank over to prime the turbos.
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I'm all for priming oil but what is the reason behind idling it for a combined 47 minutes? Are these engines prone to air bubbles trapped in the oil?
You could probably get away with less (just a single startup of the car) but the reasoning is that the oil takes forever to warm up in these cars at idle, although it's summer so Jake's car may cycle faster. Mine took a long time to warm up due to ambient oil temp being so much lower cuz I did my install in winter.
2 reasons - first is making sure you get the turbo bearings lubricated fully at normal operating oil viscosity which is safer at idle. Driving the car which is prone to accidentally getting into boost puts you at risk of damaging those brand new bearings before everything is properly lubricated. Secondly, you want to make sure that there's absolutely no leaks anywhere at normal operating temperatures before putting subframe and everything back in because taking it all apart again would be....frustrating to say the least.
I think you know these things already - it's really just the fact that oil takes longer to warm up on these cars so the idle times seem very long. Having a cold oil cycle for a couple minutes followed by another medium-length cycle is just iterative testing recommended by the BMW techs I talked to before going through the install myself. Personally I wouldn't be concerned as long as the car is allowed to cycle to full temperature at idle before putting it on the street
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Great to see progress! Keep it up! When's the murder box going in the passenger seat?
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Great to see progress! Keep it up! When's the murder box going in the passenger seat?
Thanks man! I'm not quite sure what you mean by murder box in the passenger seat though

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Thanks man! I'm not quite sure what you mean by murder box in the passenger seat though

I've also been trying to figure out what it could be...
Did Ben get a temp gun yet? If so, borrow Ben's temp gun
What's a temp gun?
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Thanks man! I'm not quite sure what you mean by murder box in the passenger seat though

I've also been trying to figure out what it could be...
I need both of you to please watch Death Proof. Basically, Kurt Russel plays a murderous stuntman who builds cars to intentionally crash and kill either the passenger or others while he remains alive. If you have any interest in Tarantino you'll like it.
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I got the oil pan cleaned up and re-installed with a new gasket. Having an industrial parts washer at my work helps. I also washed the subframe.
Then I began to swap all the lines over to the new turbos but ran into a bit of an issue. While it was my own fault, I feel like I should share for any other MMP3 owners. As Mauricio notes, you must use small washers on the bolts when reattaching the oil feed and coolant lines to the new turbos. Otherwise you will bottom out the bolt and pull the welds off that hold the mount on. Ask me how fun it is to find out the hard way.
Luckily I had a buddy who helped me weld the stainless mount back to the cast cartridge housing. It looks like it should hold just fine, but I haven't re-mounted the line yet. I might have to re-clock the turbos first. More progress tonight.
Also, if anyone wants to watch a 10 minute vlog-style video of the first day I worked on the car, check this out. My buddy @SteelBlue put it together for fun. We're curious to hear some feedback on it or if we should scrap the idea. Not a whole lot of "useful" content, but I thought it was interesting.
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That subframe is indeed many times cleaner compared to when it came off!
She's looking good, and you're on the install portion already! -
I took the long 4th of July weekend off, spent it relaxing with friends and family.
I'm officially on the back half of this install. Yesterday I got back underneath the car and mounted both turbos, gaskets, lines and torqued everything to spec. The rear inlet elbow is on (PITA), but I know I'll still have a heck of a time shoving the aluminum pipe in from up top.
Hopefully I can get back at it tonight and get the outlets, water pump, inlets, and power steering pump installed.
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I just sat and marveled at all that design and packaging for a few minutes. do you see a light at the end of the tunnel yet?
Have you looked at the center mount turbo v8 setups before? It's a thing of beauty.
Looking good! Glad to see the turbos mounted up!
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I just sat and marveled at all that design and packaging for a few minutes. do you see a light at the end of the tunnel yet?
It's definitely overwhelming, and you can only see half of it. Pretty crazy how someone (probably more than one person) designed all of this.
I see a light, but it's still pretty far away.
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Larger inlets and outlets are on. Coolant pipe, water pump, thermostat reinstalled with new hoses. Power steering pump and intercooler reinstalled. Downpipes attached and O2 sensors connected. Subframe secured with new motor mounts. Hoping to connect vacuum lines and tidy up some loose ends tonight. Should be able to start it after adding oil, coolant and power steering fluid.
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After getting some help from my girlfriend, I was able to start the car!

I was able to put on about 200 miles this weekend without a hitch. It was a great feeling being able to start the car and drive it without a single issue. I don't have the upgraded fuel system installed yet so I'm limited to low boost, but I'm okay with that because I want to break in the clutch before cranking it up to 30PSI.
These things are loud! Constant spooling noises.
I was also able to finally weigh my car: 3260lbs with a full tank of gas. No exhaust or backseats (how I typically drive it anyways).
Here's what I've replaced (off the top of my head):
- Ceramic coated MMP turbos with all new gaskets and o-rings
- Inlets and outlets, both wrapped with heat-resistant tape
- Oil pan gasket and bolts
- Oil filter housing gaskets
- Water pump and related rubber coolant hoses
- Both motor mounts
- Downpipe v-band clamps with new gaskets
- Deleted vacuum canisters, ran new vacuum line
- Power steering fluid, coolant, oil
- SPEC Stage 3+ clutch, throwout bearing, clutch fork
- Poly transmission mounts
- Aluminum bellhousing bolts
- Rear pinion seal
- Rear differential fluid
- Shifter bushings
Stay tuned - fuel system going in soon, then dyno time.
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