First step of the rebuild was to replace the oil pan as the 4.8 one was damaged which I knew before buying it
Before I could do that I needed to verify the oil pan dimensions though, since the BMW document detailing the changes to the N62TU (4.8 versions) talks about the having a deeper oil pan. After looking at them though iI can tell I was correct earlier in thinking that the change occurred midway through 4.4 production, coinciding roughly with the introduction of the E53 4.8is
Cleaned the mating surface and installed the rear main seal, oil pan, torqued to spec, as well as a new oil filter housing gasket
Once the engine was flipped over I did spend about 30 minutes cleaning the oil pan to better match the clean engine. I got it looking pretty good. Above photo is pre-cleaning
I then installed the Uro alternator bracket gasket. This is viton and an improved design. Same as what I used on the 4.4 rebuild, but a different part number because it has the gasket in the middle because this model has an oil cooler. The 4.4 showed zero signs of leaks here and the gasket was as in good condition when I removed it, so very confident in this improved part
This is the thermostat for the oil cooler and it also has it's own o-rings which I replaced
New oil dipstick o-ring
One thing I did not do yet was replace the lower oil pan gasket. I had observed during the initial rebuild a small section where the oil pan was leaking slightly. I'll get to this later.
For a moment, I looked towards the exhaust manifolds
Bank 2 4.4 exhaust
Bank 2 M62 exhaust
Bank 1 4.4 exhaust
Bank 1 M62 exhaust
Fitment actually looks much more reasonable than I was expecting
They also look really badass in my opinion
But before I can test fit, I need to properly drill the holes for the new studs. I decided to mock them up on the 4.4 to test fit before drilling holes in the 4.8 head
Bank 2 actually fit with minimal work, but bank 1 almost all of the studs are different, in the opposite position from what the M62 header flanges need. On the 4.8, all of these are off (on the 4.4, only 3 flanges are off for some reason)
Cylinders 1, 2 and 3 need to have new studs drilled before I can actually test fit the headers in the chassis. I am going to develop a technique I can replicate reliably when (if) it comes time to do this on the 4.8, this was the first stud I drilled and tapped
Which allowed me to bolt the header on properly... I still need one more stud at the minimum before I'm going to test fit it though
I also was looking stuff up and discovered that the E53 X5 used an even less optimized header design, shown below:
I then looked into it deeper and found that the E70 also used this header. This explains something I've wondered for a long time which is why there are so many different power levels listed for N62 engines of the same displacement
For example, the E53 4.4i makes 315 HP / 440 N-m whereas the rest of the N62 4.4's all have the "normal" headers I used on my swap and make 329 HP / 450 N-m
This means the X5 style headers alone accounts for a loss of 14 HP / 10 N-m
Looking at the 4.8:
E70 4.8 N62
350 HP / 475 N-m
E53 4.8is N62
355 HP / 500 N-m
Every other 4.8 N62
362HP / 490 N-m
The E70 X5 used a DISA intake with bad "X5" headers
The E53 X5 used a DIVA intake with bad "X5" headers
Other 4.8's used a DISA intake with "normal" headers
Therefore we can deduct that the difference on 4.8's between bad "X5" headers and normal N62 headers is 12 HP / 15 N-m
The difference between DISA and DIVA intake is 5 HP / 25 N-m
This would mean the baseline for an "optimized" 4.8 N62 with DIVA intake and "normal" N62 headers would be ~367 HP / 515 N-m (There were no 4.8's that came with this setup from the factory)
So if the M62 headers don't work out (and it's look like they won't as I spent more time on it) then the baseline will likely be around that 367 hp / 515 N-m figure as I will be running the DIVA intake with the good headers
Anyways, back to the refresh and picking up on something I left off earlier. I ordered a new gasket for the lower oil pan, but noticed on RealOEM it says to "use with Loctite 5970". This sent me down a bit of a rabbit hole because TIS does not mention it - it just says to install the gasket and torque to spec. I didn't think too much of it at the time but later on I went researching what the Loctite 5970 is for and it ends up that on modern BMW engines, they don't use gaskets on oil sumps and differentials and many other locations. They only use a bead of that Loctite 5970 sealant. I think Mercedes has also been using this stuff for years instead of traditional gaskets
As a result of this, I have decided I am going to skip the gasket - I am going to use the Loctite 5970 alone to join the lower pan to the upper pan. Clean the mating surface, apply a ~2mm bead, apply both parts within 10 minutes and torque to spec
The loctite sealant is really tacky and it seems like it will do a good job, at least I hope so. I cleaned up what squeezed out the outside of the pan, hoping I didn't squeeze too much to the inside!
I also installed a new gasket on the oil level sensor
Then I turned the engine upright and got working on the valley pan stuff
Re-used the URO/APA collapsible coolant pipe but with new gaskets/seals
Also installed the water pump, knock sensors (they were cut by the junkyard that removed them), crank hub pulley, tensioner. Lots of small things, but now the main focus will be valve stem seals, valve cover gaskets and then the rear coolant distribution cover will be done later once the engine is off the stand
Then I did the VANOS solenoid o-rings, upper timing chain gaskets, vaccuum pump o-ring, etc etc
Valve stem seals done
Almost done... just need to install the new valve cover gaskets, I was waiting on them when I took this picture and just set the covers in place to protect the inside of the engine
I then got the AN10 adapter pieces for the thermostat and oil cooler
I was planning on running the lines up over the alternator but after looking at it now I think running them down will be better for chassis clearance. That may change once I get the engine in place but for now this is the plan
On the home stretch I decided to spend some time polishing the valvetronic motors just a little bit. The one on the right is done at this point. They didn't come out perfect by any means and I could have spent more time on them but I was happy enough with where they ended up. I just wanted them to not be an eyesore since they are so centrally located on the engine - but I didn't want them to be too shiny, because the intake manifold will never be able to maintain a shine (the intake is magnesium) and I didn't want that contrast
All done with new valve cover gaskets and all the other little small things, I also re-installed the wiring harness
Next I focus on some chassis stuff I want to re-do now that the engine is out! On to Part 33
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