N62 Z3 Part 33: Chassis Work & 4.8 Installation

Before the engine goes back in I wanted to fix some chassis stuff that had bothered me and the biggest one was the power steering reservoir bracket I installed. So that had to go! Below is how it looked before

That was one of my biggest regrets so let me fix that...

I'm going to paint the shock towers and the sections forward of them including the radiator core support, so I started prepping that area for body filler prior to paint

While waiting on the paint to arrive I decided to work on another small chassis side project which was replacing the steel line on the coolant bleeder line. This was rusting internally, so I replaced it with aluminum line

I did the one on the engine as well

Back to the chassis though, I noticed on my last few drives a slight "click" when steering and a little bit of play in the steering. Not a whole lot, but enough that I wanted to do something about it now that the engine is out

I diagnosed it as being the heim joint itself having some play between the inner cup and the outer assembly. You could grab the steering shaft and jiggle it a little bit and feel it move and hear it click metal on metal. So, I found a high quality bearing I'm going to install instead of the heim joint. First step was to make a bracket. This is two pieces of 1/4" welded together to get suitable thickness for strength

Then I marked where I needed to drill and drilled out some holes for mounting bolts on the bracket

I had to trim away the outer two mounting holes on the bearing, they were not needed for this application

Idea was to mount it here

After numerous test fits and tack welds and moving things around I got the bracket where I needed it and did a few more tack welds, removed the bearing and then went to town welding it in. They are not the prettiest welds, but there are plenty there - the below photo is maybe halfway through the installation

Installed in place

Previously I also had a little piece of metal on the upper section of the steering shaft (visible above in previous images) that was there in case the engine flexed under load so it didn't bind against the shaft. I never had any evidence of this actually happening but decided since I had the spare heim joint that I should install it in that area instead

It also serves a second more important function of being a backup method of holding the steering shaft in place in the extreme event of the bearing or bearing bracket failing. This should inspire a little more confidence in the steering system at high speeds or when blasting through tight mountain roads. It's a little hard to see, but it's shown installed below

Everything is done with body filler at this stage. Needs a bondo skim coat to finish it off then paint it and this work is done

I didn't get a picture of the bondo stage but here it is in primer

I wantd to paint it next but the paint can was damaged, Eastwood sent me a replacement but while waiting for it to arrive I got the oil cooler and power steering coolers installed. I later painted the non-radiator surfaces black so they blend in a bit better once everything is installed

And painted... now it's ready for the engine to be re-installed

But before I could get ahead of myself, I needed to prep the bank 1 header. It sits a little further "outwards" than the original header I used on this side and it was 2.5" right behind the O2 whereas the original 4.4 one I had was 2"

The good news is the mid-pipe I built last time was all 2.5" so I already had plenty of that size pipe laying around. I bought some 2.5" v-bands and tack welded it up, where it looks like fitment may work out. After spending a couple hours analyzing previous images of the bank 1 header and fitment I decided to move the V-band from where it is shown below prior to test fitting it

I then test fitted the engine and the rear section fit perfectly but the front was rubbing the frame. You can also see where the v-band was moved to. It may have been ok in the original position but not positive

So I took the engine out again, welded a pocket here around the header and test fit it again... tight, but it fits

Then I welded that header up. I also put proper heat wrap around the crank sensor wiring

Things are so tight that I can't even remove the mount nut when the engine is resting on the mount

When the engine was out I also secured the alternator cable to the engine on this side. Previously it had sagged into the header and started to melt the plastic conduit a little it - you can see some plastic residue on the header around cylinder 7

Then I worked on the oil cooler fitment and fabricated the AN10 lines

Test fit everything with the power steering reservoir bracket and the lines to the p/s cooler

How everything is looking so far

I then took the engine back out and started to work on the exhaust. I could have just re-worked the mid-pipe I had built before but I wanted to add flex pipes and the previous iteration sat a little too low - it would scrape going over speed bumps. So I tucked it up as high as I could this time and managed to get it to sit at the same height as a factory exhaust

I then re-installed it for the last time before final installation so that I could verify the mid pipe section was going to fit. Everything fit perfect, so out it comes to finish the mid-pipe

With it back out I worked on welding the rest together. I repurposed the X pipe and resonator section from the previous midpipe. I also started heat wrapping the pipe at this point

I then worked a bit more on the heat wrapping, the headers need the section behind the O2 sensor done and then the heat wrapping is finished. I also added an exhaust mount on the transmission brace. I wanted this to serve two functions, most important was to support the front of the midpipe, it only had two rear mounts before and I was afraid this would be constantly stressing the flex pipe sections so I wanted that extra support. The other function is to aid in installation, being able to install it onto a hanger first makes it a lot easier to manuever the front section onto the v-band flanges

At this point I was about ready to install the engine... but I wanted to re-do bank 2 because of some sharp angles and in thinking about it, the bank 2 header started to feel off to me. The reason I was using the 4.4 part is that I had a photo sent to me from a seller of a "4.8 exhaust manifold" showing the same inner diameter pipe at 2" that was on my 4.4 manifold. But when I looked closely at the image it didn't entirely look like a 4.8 header. They are slightly different visually and what they sent me looked like a 4.4 part

So I did more research. The part numbers are different, but the N62TU technical document says they used a different catalytic converter coating for faster warmup, which is why the TU engines were able to eliminate the SAP. So I knew the cats were different and because the cats are integrated into the manifold, the different part number didn't provide a definitive answer. I kept looking at pictures of the 4.8 headers online, on ebay and anywhere else I could find a photo of one

I couldn't get an answer for sure one way or the other, but I knew I didn't want to put the engine in and constantly be wondering "is this header less efficient? did I leave some power on the table by re-using the 4.4 manifold?". This was especially pertinent because the bank 2 design is inherently worse than the bank 1 double Y design. So I went hunting for the 4.8 specific header. I found one, with the catalytic converter, for just under $200 shipped from some junkyard in Tennessee. And boy I am glad I did, because they are different...

Top is the 4.4 - it's hard to tell because the exteriors appear visually quite similar - but the 4.4 had an inner diameter pipe that was 2" (that's why you see it go to a 2" - 2.5" upsizer right after the O2 . The 4.8 manifold did not have this interior pipe section and it was 2.5" at the exit

The primaries may also be slightly different but it's really hard to tell

This was the work in progress of re-building the bank 2 side of the exhaust

This is how bank 2 ended up looking, sans heat wrap

Bank 1

And the finished midpipe

Then the exhaust manifold gaskets finally arrived so I got the headers on for good after heat wrapping bank 2 and in it goes...

The installation is a bit of a process... I'm actually going to write out the full process in detail for my own future reference but a short synopsis is that you lower it roughly into place, use a jack to raise the transmission slightly, pull the bank 1 engine mount forwards to guide it into the mount then lower the engine down, as it lowers it moves rearwards and slides into position. Get the nut tightened just a few threads on the bank 1 mount, raise the engine back up, pull the engine mount on bank 2 forward and guide it into the engine mount as you lower the engine, fully tighten bank 2 nut, then raise the engine back up slightly to allow access to the nut on bank 1, tighten and as it tightens you'll also be lowering the engine slightly as the nut moves down... and that's just for the engine mount nuts! You also have to use a 1/4 ratchet because clearance is so tight...